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Korg Monotribe modifications thread
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Author Korg Monotribe modifications thread
pulse_divider
I saw there was already a thread asking about specific modifications but I can't seem to find any centralized information on what modifications are possible for the Monotribe and how to achieve them. I'm sure this info will slowly creep out as they are now shipping in large numbers and I'm hoping to have a dedicated thread to refer to as I try and muck with mine.

So, has anyone modded theirs yet?
What have you done, and how did you do it?
I have yet to figure out how to open mine, the 3 screws on the back seem to serve to hold the jack board in place, I can't figure out how to get the case open. Those of you who've had it open, how did you get the case apart?

Supposedly there are pads on the board for modding the drum sounds (a la the Bass Decay YT video) but I haven't seen a picture of the insides yet, anyone have one?

My #1 want for a mod is individual outputs for the drums and synth. Trigger outs would be nice too but I could live with audio outs and generate triggers from those.
Low-Gain
I haven't cracked mine open yet but i fully intend to in the next few days.

Individual outputs (drums and waveforms)
Trig I/O
LFO Reset In
External LFO
to name a few... are what i'm looking for.
I'll get into the drum voicing eventually. I really like how they sound, def gotta have individual outputs though!

I'll post my findings here
Vcoadsr
pulse_divider wrote:
I saw there was already a thread asking about specific modifications but I can't seem to find any centralized information on what modifications are possible for the Monotribe and how to achieve them. I'm sure this info will slowly creep out as they are now shipping in large numbers and I'm hoping to have a dedicated thread to refer to as I try and muck with mine.

So, has anyone modded theirs yet?
What have you done, and how did you do it?
I have yet to figure out how to open mine, the 3 screws on the back seem to serve to hold the jack board in place, I can't figure out how to get the case open. Those of you who've had it open, how did you get the case apart?

Supposedly there are pads on the board for modding the drum sounds (a la the Bass Decay YT video) but I haven't seen a picture of the insides yet, anyone have one?

My #1 want for a mod is individual outputs for the drums and synth. Trigger outs would be nice too but I could live with audio outs and generate triggers from those.


You can easily open it by lifting up the four rubber feet and you'll find the screws to take the back off.

So far I have found no markings/text that show where a CV pitch mod could be started. There is text for the drum parts but I'm less interested in those when compared against the CV Pitch control and gate.

So far it looks to be a lot more complicated to mod than the Monotron.

I will watch this thread with anticipation!
Malekko
Hopefully mine gets here today~

Dinner at the Y w00t
pulse_divider
Vcoadsr wrote:


You can easily open it by lifting up the four rubber feet and you'll find the screws to take the back off.

So far I have found no markings/text that show where a CV pitch mod could be started. There is text for the drum parts but I'm less interested in those when compared against the CV Pitch control and gate.

So far it looks to be a lot more complicated to mod than the Monotron.

I will watch this thread with anticipation!


Thanks for the tip, I finally got it open! Yes, it looks like all the mod points are for the drums, but this is what I want. I'd actually be more interesting in a CV/Gate output mod, the sequencer is the fun part. Neither is really important to me, though, decay mods and individual outs will make me very happy.
Here are some pix of the insides.
pulse_divider
Also, just noticed that Korg is still labeling boards with the KLM prefix... I know my old PS-3100 also shared this naming convention and think most of their vintage (Lambda, PE-1000/2000, Sigma) analogs did?
3vcos
OOOOHHHHH

thanks for the pics. Any chance you could post some high res shots?



pulse_divider wrote:
Vcoadsr wrote:


You can easily open it by lifting up the four rubber feet and you'll find the screws to take the back off.

So far I have found no markings/text that show where a CV pitch mod could be started. There is text for the drum parts but I'm less interested in those when compared against the CV Pitch control and gate.

So far it looks to be a lot more complicated to mod than the Monotron.

I will watch this thread with anticipation!


Thanks for the tip, I finally got it open! Yes, it looks like all the mod points are for the drums, but this is what I want. I'd actually be more interesting in a CV/Gate output mod, the sequencer is the fun part. Neither is really important to me, though, decay mods and individual outs will make me very happy.
Here are some pix of the insides.
machetemirage
I would go for a monotron "modbox", a separate unit with knobs and jacks for all of that. Also, I'm hoping someone crafty will get LFO and Osc outs somehow...
pulse_divider
3vcos wrote:
OOOOHHHHH

thanks for the pics. Any chance you could post some high res shots?



Edited for larger photos, I think that's the largest it will allow.
andrewF
nice pics, I want!
Low-Gain
machetemirage wrote:
I would go for a monotron "modbox", a separate unit with knobs and jacks for all of that. Also, I'm hoping someone crafty will get LFO and Osc outs somehow...


In theory if the waveform select switch is done in an analog fashion... then each waveform should be at each of the points on the switch. toss in an output buffer and you've got individual outputs. Not to mention the noise out put at the pot. So that wont be a problem either. :-D

And of course you start poking around the EG switch and i'm sure hoping to find some stuff to start playing w/ the EG.. or at minimum.. allow me to find a VCA CV input... Assuming this entire synth section is analog.
It's all just a matter of following signal flow... Much like the NovaMods on an SH-101.
pulse_divider
What would the SD Frame Out be? Pitched portion of the snare drum?
darenager
Exactly
computer controlled
Its weird they would have the SD Frame and Noise on their own outputs.
phono1337
computer controlled wrote:
Its weird they would have the SD Frame and Noise on their own outputs.


It's probably a test point rather than an intended output
darenager
Yeah, but with the added bonus of allowing each part to go to each side of a pot, then take the output from the middle pin of the pot, voila a nice tone/snappy control for the snare w00t
Veqtor
Hmm, I am considering getting one.... Would be cool to try and attach a mini patchbay to it.
chando
It would be great if someone figures out how to turn off the OSC... so it can be useful for ext filtering...
th0mas
-- ADVANCED IDEAS --

So, I have this theory. It's only a theory, and it's slightly crazy, but it's a theory until being disproven.

- there is a microprocessor on board. It's a Toshiba ARM
- the microprocessor has a hardware serial input.
- there was probably left over code space. The sequencer is simple.
- it would have been free to have basic MIDI handling code on that microprocessor. Space is there, code would take a few days max and they probably tried it.
- it would have been annoying to make it fully featured (full range, pitch bend, channel selection, pattern dumping, full clock support, etc..)
- it would have cost $ to actually wire up the optoisolator and MIDI socket, so they left it off.

So basically my theory is, if you attached the standard MIDI input circuit to the serial input of the toshiba micro controller.. maybe MIDI will just work to some degree smile woah

Other theory is that they didn't disable reading the firmware back from the chip so you could, with the debug interface, read the code back and then modify and reupload it. again, total theory smile

these are currently relatively crazy thoughts. ive been drinking. w00t
nitro2k01
Hmm, could someone please tell me the exact model number on the CPU chip says? Or better yet, a nice crisp photo of the CPU chip.
pulse_divider
nitro2k01 wrote:
Hmm, could someone please tell me the exact model number on the CPU chip says? Or better yet, a nice crisp photo of the CPU chip.


which one is it in the picture? Or is it on the other side of the board?
nitro2k01
Must be on the other side of the board. It's likely the chip with the most pins. Probably a square one with pins on all four sides.
computer controlled
mckenic
Dont know if its that my ears are old & shot, the beers Im drinking, youtube or my monitoring set-up... I certainly can hear changes on the snare and hats but no difference on the Bd seriously, i just don't get it

Still - exciting times hyper
Veqtor
Truly exciting times, I might actually pick one up... if so then I plan on finding a box that's about the same height and depth of the monotribe and adding a small patchbay and some extra switches etc. I'll attach the box to one of the sides to make it wider...

Would probably be fun to fm the osc w. the bd, sd frame etc...

Lotsa stuff to be done... Just wish it had an reset in...
pulse_divider
mckenic wrote:
Dont know if its that my ears are old & shot, the beers Im drinking, youtube or my monitoring set-up... I certainly can hear changes on the snare and hats but no difference on the Bd seriously, i just don't get it

Still - exciting times hyper


The kick decay only seems to affect the low frequencies, not the attack.
And the snare decay knob affects the pitched portions while the switch affects the noise.
Pretty cool! I listened on my Ipad earlier and thought "meh" but now that I'm in the studio in front of the monitors it sounds worthwhile.
mckenic
Ah! Thanks!

The fan on my laptop kills low freq listening so I'll have to listen with headphones! I just thought I was too old to hear it smile
th0mas
It's a Toshiba TMPM332FWUG http://www.toshiba-components.com/microcontroller/TMPM330.html

data sheet here http://www.semicon.toshiba.co.jp/openb2b/relateddocument.jsp;jsessioni d=CB9D00ABA607526125089B406E1152D6?did=21741&lang=en&pid=TMPM332FWUG&r eturnFlag=1
darenager
I think I'd be inclined to go for some less subtle mods, I think the monotribe kick is perhaps a little too low in frequency for my taste so I might try to have it a bit more punchy.
glitched01
If the community figures out the CV/gate/trigger stuff, the Monotribe will go down as the most affordable semi-modular "groovebox" ever!
Veqtor
New definition of misjudging the electronic music instrument market:
1) Build a device that replicates a tb-303 but with ms20 filter and three analogue drum sounds + performance sequencer
2) Hype it all over the web
3) Make ~500
4) Sell them for €150 each
5) Get surprised when they sell out

----------------

Oh well... I got to try one today, I must say it sounds a lot better than in the pesky youtube and mp3 demos I've heard, the bass rips through really well and the snare has enough punch, also wondering if they've implemented some kind of cheap compressor or saturation on the output amp because the mix sounded really thick and punchy. I hope they don't realize how good it is given that I think a lot of ppl would buy it even if it was priced at ~€250.

I hope its internal gate signals are strong enough to clock my modular, I hope to compliment it with a uZeus skiff running off a battery-pack containing a René, phonogene, modemix and maths, if I can squeeze that in there. Would be ideal as modular busking system razz

-------

On the mod side of things:
What about using a NSL32sr3 for cv control of the decay times?
phono1337
Veqtor wrote:
tb-303 but with ms20 filter


thats pretty far off tbh ;-)

























(ok i'm a purist)
goiks
Veqtor wrote:

I hope its internal gate signals are strong enough to clock my modular, I hope to compliment it with a uZeus skiff running off a battery-pack containing a René, phonogene, modemix and maths, if I can squeeze that in there. Would be ideal as modular busking system razz


just got a monotribe yesterday, sounds great with a little gain from my metric halo box. been clocking this from it, running everything from a uzeus, very fun combination! veqtor, make me a battery pack while you're at it!



chando
Maybe I'm crazy .. but I wouldn't even waste my time modding the drums seriously, i just don't get it

Individual outputs would be very tasty.. but once again I need a way to turn off the oscillator so it can be a decent filter... if not I'll just keep waiting and praying for a decent deal on a Waldorf MiniWorks desktop..
aksen
chando wrote:
but once again I need a way to turn off the oscillator so it can be a decent filter...

yeah, curious why they went backwards on that feature from the monotron.
chando
But the Monotron was just free running.. no real fun there.

Dammit!! I just want a filter that I can sequence. My SH-7 did it really well but that was overkill..
Nils
would a mod converting the mono audio output to a stereo output (tip - synth, ring - drums), be doable/easy? I don't want to modify the housing..
Low-Gain
Just an FYI... the 9V adapter input on the back is not a standard 2.1MM plug.. I plan to mod mine to take a normal Boss style center negative (isolated jack) 2.1mm 9V wallwart. To make life a little easier.

Batteries last a little while, but not long enough.
Sir Ruff
goiks wrote:
Veqtor wrote:

I hope its internal gate signals are strong enough to clock my modular, I hope to compliment it with a uZeus skiff running off a battery-pack containing a René, phonogene, modemix and maths, if I can squeeze that in there. Would be ideal as modular busking system razz


just got a monotribe yesterday, sounds great with a little gain from my metric halo box. been clocking this from it, running everything from a uzeus, very fun combination! veqtor, make me a battery pack while you're at it!





wow... that's a beautiful case/setup - I'd be curious to see what modules you've actually got in there (being less familiar with euro stuff at a glance)
goiks
Low-Gain wrote:
Just an FYI... the 9V adapter input on the back is not a standard 2.1MM plug.. I plan to mod mine to take a normal Boss style center negative (isolated jack) 2.1mm 9V wallwart. To make life a little easier.

Batteries last a little while, but not long enough.


i went through all the different adapter tips at radio shack and none fit, i read somewhere that the korg ka350 ac adapter will work, but haven't tried it yet. kinda lame that it's not included, they must haev been really trying to keep the price down.

@ sir ruff- thanks, that's most of the makenoise lineup, and the harvestman's oscillators, with a ustep and uscale from intellijel.
Low-Gain
yeah. i'll look at the foot print. can probably swap out the connector for a standard 2.1mm.. I'll likely just drill a hole in the back and mount one of my panel mount 2.1mm connectors that i use on FX pedals.
simple fix.. 3 wires... 1 hole, 1 connector.
nitro2k01
Considering software hacks... Most likely they've set the protection bit so that the current software can't be dumped. If one were to try and develop an alternative software, you would lose the original firmware as soon as you upload a your own stuff for the first time. If I'm not misunderstanding the documentation for the microcontroller, there's also away to lock the flash from being written to, which would mean that software hacking isn't possible at all, unless you replace the microcontroller chip. OR in the best case scenario they've just left it unlocked. I'll try to investigate.
dualmono
Just for completeness:
Keep an eye on this blog.
StepLogik
th0mas wrote:
It's a Toshiba TMPM332FWUG http://www.toshiba-components.com/microcontroller/TMPM330.html

data sheet here http://www.semicon.toshiba.co.jp/openb2b/relateddocument.jsp;jsessioni d=CB9D00ABA607526125089B406E1152D6?did=21741&lang=en&pid=TMPM332FWUG&r eturnFlag=1


Interesting choice of CPU. That is a 32 bit model and also has a lot of extraneous features that seem completely unnecessary for the Monotribe.

Also interesting is the 10 channel A/D converter and no D/A facilities that I can see. I'm guessing they are using an external D/A, probably connected via I2C. I'm curious as to what those 10 A/D channels are used for. Seems like only 2 or 3 would be needed: input for the ribbon, input for the VCO output for continuous pitch calibration, maybe an input for the tempo knob. Seems like the rest of the knobs would be connected directly to the analogue hardware.

Can't wait for schematics for this thing, either reverse-engineered or official ones from Korg!
nitro2k01
StepLogik: Actually only 8 channels, but that chip is the lowest spec chip in that group of microcontrollers. As for it being a 32-bit model, that really makes sense. The math required for the pitch detection/calibration (and maybe other things) becomes so much easier when you have more bits than 8 to do math with. Perhaps one ADC channel is used for the sync input as well, but that remains to be seen. That might just as well be done with analog+discrete digital circuitry, (comparator+level shifter or something) and then a digital pin connected to an interrupt.

Also, you wont see any official schematics for this from Korg, I don't think. wink
StepLogik
nitro2k01 wrote:
StepLogik: Actually only 8 channels, but that chip is the lowest spec chip in that group of microcontrollers. As for it being a 32-bit model, that really makes sense. The math required for the pitch detection/calibration (and maybe other things) becomes so much easier when you have more bits than 8 to do math with. Perhaps one ADC channel is used for the sync input as well, but that remains to be seen. That might just as well be done with analog+discrete digital circuitry, (comparator+level shifter or something) and then a digital pin connected to an interrupt.

Also, you wont see any official schematics for this from Korg, I don't think. wink


Def agreed on the 32 bits. That combined with the number of timers available on that model also makes me wonder if some envelope calculations aren't being done by the CPU as well.

Yeah, I doubt Korg is going to release these schematics! very frustrating But, I'm hoping someone will reverse engineer it. I'm very curious to see how much is actually implemented in hardware vs. software.
computer controlled
I wonder how easy it is to drill through that case.

I also notice the pots work backwards. What's up with that? seriously, i just don't get it
th0mas
The first thing I would do is wire up the standard MIDI optoisolator circuit and connect it to all the hardware UART pins on the CPU. It's possible there's code on there to listen for MIDI input but they left off the circuitry to save money...
Low-Gain


Sorry for the crap picture.. i dont have photoshop installed yet.
And i dont know how to use Gimp. lol. Center lug on the VCA pot is the VCA output... and the 3 positions on the waveform switch are the individual wave outputs.

I tested these tonight.. haven't wired them up yet. but they work.. use a 150-1000 ohm resistor on each output.

Enjoy!
nitro2k01
CONFIRMED! It is actually spitting out proper MIDI on the serial line! It gives you the following:

Note data.
MIDI sync, incl. start and stop messages.
Automation data for all of the LFO settings (both the knobs and the switches) and the EG shape. This suggests that the LFO and envelope may be created in software.

I have not yet hooked up an optocoupler and fed the thing MIDI from the other end, but I will. Shorting the serial out and serial in ports glitches the thing, so it most probably is capable of receiving MIDI.

Here's the pinout for the pin connector marked serial on the board.
Code:
CN12   MCU
1   Pin 20 PH0, TB0IN0, /BOOT
2   Pin 12 RXD0
3   Pin 11 TXD0
4   Pin 9  Vdd (3 V)
5   Gnd
6   Pin 29 PF6/SCK1

I believe this header was intended for factory programming of the firmware. When pin 1 is held low, the MCU enter a special programming mode, according to the datasheet. Pin 6 goes is routed up to somwhere near the power switch and is probably used to detect when a unit is turned on to begin the programming.

CN13 (which comes with no connector attached) would be used for debugging, but it is likely that debugging is disabled so you can't dump the firmware etc. Still haven't looked into that. (I don't have JTAG tools readily available, so...)

But what we're interested in is pins 2-5. Pin 2 is for receiving MIDI. Pin 3 is where MIDI comes out. If you're going to try to add an optocoupler, you'll also need Gnd and Vdd.

MIDI is a current loop protocol, so 3.3 V is no problem for standard MIDI gear given that you adjust the output resistors accordingly. Following the standard MIDI convention, I connected 3.3V and the output as usual, but replaced the usual 220 ohm resistors with 150 ohm ones. Works well enough.

I also got an idea: If the monotribe can receive MIDI, that may open up the possibility of throwing the internal oscillator out the window and using the it as a self-tuning MIDI CV interface for modulars. However, I've found that at least my monotribe tracks badly and sometimes drifts a little. This is especially obvious when comparing it to a well-tuned computer playing the same MIDI notes. Also, it's using just 5V internally for the analogue part (3.3V for the digital) and the CV range may be even less, so perhaps it wouldnn't be of much use for 1 V/oct systems.

More to come...
th0mas
nitro2k01 wrote:
CONFIRMED! It is actually spitting out proper MIDI on the serial line!.


YES YES YES YES YES YES SlayerBadger! SlayerBadger! SlayerBadger! I KNEW IT! grin Dead Banana
nitro2k01


and a video perhaps?
computer controlled
Interesting
Veqtor
Post of the month! Hack of the month! Etc!
Now lets see midi in! Mr. Green
Nils
Great work Nitro!
mckenic
This makes the Monotribe X10 more interesting...

Midi In/CV in X1000...

Thank you very much for sharing your results - It's motherfucking bacon yo
Low-Gain
F' midi! razz
SYN7HOR
nanners
mckenic
Well pitch CV in would be wonderful... more than 8 steps would be fap fap fap...
3vcos
mckenic wrote:
Well pitch CV in would be wonderful... more than 8 steps would be fap fap fap...


It already has 16 steps. (read manual or check out videos)
mckenic
Well that I didnt know!

Guess I need to look for different vids as all I saw was 8 bar loops with blokes tweaking the filter!
nitro2k01
3vcos wrote:
mckenic wrote:
Well pitch CV in would be wonderful... more than 8 steps would be fap fap fap...


It already has 16 steps. (read manual or check out videos)
Only the drums. The synth is still only 8 steps.
mckenic


seriously, i just don't get it

EDIT - Thanks nitro... Im sure there are very creative ways to use this and I cant wait to get my hands on one but it must be me... even 16 steps aint enough for me to get my ideas out these days. Perhaps I need to rethink my thoughts on sequencing. Funny tho because most guitar songs I write have only two chords hihi
monobot
So maybe you should get more familiar with the flux mode or try the pitch cv control presented here: http://monomodder.blogspot.com/2011/08/monotribe-pitch-control-cv.html
kcr
The maddening thing is that the 8 steps is clearly a UI/software limitation.

Someone will figure out how to read out and write in the firmware soon enough, I suppose.
Veqtor


I got to see the "holy fuck" moment first hand! thumbs up
mckenic
Holy f'in Fuck!

Wow! we're not worthy
Sir Ruff
Veqtor wrote:


I got to see the "holy fuck" moment first hand! thumbs up


So how did he figure out what parameters are automated/use CCs/Sysex?

From the sound of it, it seems like every parameter responds to midi?
Veqtor
Well, it appears that the parameters that send midi also respond to midi. Like lfo rate and depth, lfo shape, lfo destination, lfo type. Their cc numbers correspond to the ones they send out.

But controls like cutoff, res, osc wave and the volumes (synth vs drums) are analogue so they don't have any midi parameters ofc
giorgio
Om Om Om Om Om Om Om Om Om Om Om Om Om Om Om Om Om
minphase
If you're driving the monotribe from an external clock source (like an ancient DR-55) via the gate/sync input, does the monotribe send midi clocks at a proportional rate, via the midi out pins just discovered? Awesome stuff, nitro2k01 !
nitro2k01
minphase: Haven't tried, but my bet is no. The external sync input only takes one pulse per step, whereas MIDI is 24 PPQ (pulses per quarter note). So in order to output MIDI sync from external sync, it would have to generate a lot more pulses than it receives.

Actually, it does interpolate sync clocks already for the extra steps for the drums. If you send a sync pulse into the jack on the back, the monotribe will place the secondary drum hits between the sync pulses, so maybe it'll output MIDI clocks after all.
giorgio
i bet the microprocessor drives the whole clocking system of the thing, and probably processes the analog sync input. therefore it'd probably spit out midi clock either way, if it spits out midi clock at all (can't 100% tell from the vid or info above but seems like it might)
rico loverde
MY ASS IS BLEEDING Gotta get me one.
exper
hyper

So, what is involved in getting MIDI into the monotribe then? Simply wiring a MIDI jack to the serial port inside? The first person to offer this interface resonably gets my money! Since getting started with my modular, I lost interest in the monotribe, but now... something wonderful
DBM
Sir Ruff wrote:
Veqtor wrote:


I got to see the "holy fuck" moment first hand! thumbs up


So how did he figure out what parameters are automated/use CCs/Sysex?

From the sound of it, it seems like every parameter responds to midi?


So can we see what all is needed to hook it up ?
If it's as easy as it sounds I may have to eat my words on not being interested anymore ( VSE )

BTW Hi I'm new 1st post and all that ....gameboy genius's vid lured me in


exper wrote:
hyper

So, what is involved in getting MIDI into the monotribe then? Simply wiring a MIDI jack to the serial port inside? :


What he said
nitro2k01
exper wrote:
So, what is involved in getting MIDI into the monotribe then? Simply wiring a MIDI jack to the serial port inside?
More or less, yes.

Standard schematic for reference:


For MIDI in, you should ideally add an optocoupler to adhere to the MIDI standard, and to avoid ground loops when possible. You *can* skip the optocoupler, this is what I did when testing. However, since the microcontroller is 3.3 V and MIDI is 5 V, you need to add a resistor in series with the serial line, since the chip could be damaged by directly connecting voltages above 3.3 V. Even doing that, you're going slightly outside the specified limits of the chip, even though the chip should probably be able to handle the pressure with the added resistor. I used an 820 ohm resistor which seems to work fine. However, I wouldn't do this for a production version of this mod. I will look into suitable optocouplers to use.

Similarly, for MIDI out, you can get away with just connecting two resistors (One that goes between 3.3 V and the power pin of the MIDI jack, and one that goes between the serial output and the serial pin of the jack.) Once again, you can get away with a slight modification of the MIDI standard. In a standard MIDI circuit, the job of the transmitting side is to light up a LED at the receiving side. There are three resistors (two on the transmitting side and one the receiving side) in place to prevent various kinds of damage, like output to output connection other faults.

The transmitting side will work in a standard circuit so long as it manages to light up the LED in the optocoupler on the receiving side. I found that replacing the 220 ohm resistors labelled Ra and Rc in the schematic above to 150 ohms works ok. Again, your mileage may vary. Although it's unlikely, some MIDI circuits may use some other brand of optocoupler than mine and not light up with just 3.3 V. And something like a bus-powered MIDI hub probably wouldn't work reliably or at all at only 3.3 V. Again, if I were to install this mod, I would probably go for 5 V operation.

Note however that MIDI out is pretty much useless. You only have your 8 sequencer steps, of course. And also, the CC data from the knobs lags an awful lot. If you wiggle a muff really quickly for a couple of seconds, it will take several seconds before that has been fully transmitted. I'll have to verify that this is not a problem with my computer or anything, but it looks as if the monotribe really is that slow at transmitting MIDI.

And I managed to get a few weird glitches when sending MIDI from Reaktor, such as hearing a weird noise, possibly the machine's self-tuning process. Maybe there was a good reason they didn't officially include MIDI in the product specifiation...

More info will come in a while.
DGTom
MY ASS IS BLEEDING

I had been holding out hope that the leploop would kill all my desire for boxes. . . epic fail

clocking the monotribe from the leploop sequencer would be nuts. . . if it could take that & spit out midi, shit on me MY ASS IS BLEEDING
nitro2k01
DGTom: Well, I left my cable at the lab, but I will check later if it gives you MIDI sync from the external sync input. Based on my observations about how the sequencer plays secondary drum hits, the sync input would have to be pretty stable if you don't want it to miss a MIDI sync message here and there. You couldn't do swing or anything like that. Also, based on how it seems to buffer data you might get lag of the sync signals whenever you turn the LFO rate/depth pots on the monotribe.

Maybe you're looking at it from the wrong angle? I don't really know anything about the leploop, but it seems to have a MIDI in. Maybe what you need is a master MIDI sync device to clock both machines? I take it there's no sync INput on the leploop?

Oh and BTW... A good thing about using the monotribe as a MIDI slave, is that you can reset the sequencer remotely, which you can't using only the sync input on the back.
DGTom
if you can check it out that'd be great, any lag / correction / glitch can be usefull. . . I'm always on the look out for odd behaviour to exploit.

I'm syncing my leploop to an EHX 2880 via midi atm, ideally I'd like to go either way.

Stock the monotribe is cool, but, I'm watching to see where the mods take it grin

An analog Reset in & access to this double speed clock + drum section clock in would be awesome!
aksen
MY ASS IS BLEEDING Dead Banana

daaaaaaaaamn...this little box is turning into a real gem. glad i got me one. of course, i don't know a soldering iron from a waffle iron, but hey...
bartleby
nitro2k01 wrote:
DGTom: Well, I left my cable at the lab, but I will check later if it gives you MIDI sync from the external sync input.

while you're at it, could you check something else: is it possible to trigger the monotribe's sequencer externally with rhythmic analog pulses, like from an rcd or scm, and get it to spit out midi notes triggered by that analog signal?
Veqtor
bartleby wrote:
nitro2k01 wrote:
DGTom: Well, I left my cable at the lab, but I will check later if it gives you MIDI sync from the external sync input.

while you're at it, could you check something else: is it possible to trigger the monotribe's sequencer externally with rhythmic analog pulses, like from an rcd or scm, and get it to spit out midi notes triggered by that analog signal?


This is possible with a stock monotribe I think... I hope to add a jack that sends out a "midi stop" message to reset the sequencer for crazy polyrythms...
nitro2k01
bartleby wrote:
while you're at it, could you check something else: is it possible to trigger the monotribe's sequencer externally with rhythmic analog pulses, like from an rcd or scm, and get it to spit out midi notes triggered by that analog signal?
RCD? SCM?
The pulses must be clean. It's looking strictly for a positive (or negative depending on the setting) edge. If you would use something like a metronome noise click or a percussion hit on the sync input, it might trigger multiple times because there are several positive edges in the signal.

As far as I've observed, it will always send MIDI notes when it plays something on its own synth, whether you're playing on the ribbon, or whether sequencer is triggered internally or externally.
DGTom wrote:
An analog Reset in & access to this double speed clock + drum section clock in would be awesome!
Excellent idea! Analog reset might or might not work. You could add e.g. a microcontroller that that detects an incoming analog pulse and resets the sequencer over MIDI. That's trivial. However, sending a MIDI stop and start command might force the thing into "MIDI slave mode" where it will only react to MIDI sync and not its internal sync generator or external sync. Of course, a cheap way around this is to let the microcontroller "push" the start/stop button to restart the sequencer. Sometimes simple solutions are the best ones. Anyway, not impossible.

Also, keep them ideas coming. If there's enough interest, I might offer kits and/or modification services.
bartleby
Veqtor wrote:
bartleby wrote:
is it possible to trigger the monotribe's sequencer externally with rhythmic analog pulses, like from an rcd or scm, and get it to spit out midi notes triggered by that analog signal?


This is possible with a stock monotribe I think...

uhm, except that a stock montribe doesn't have midi out? smile

nitro2k01 wrote:
RCD? SCM?

rotating clock divider, shuffling clock multiplier.

nitro2k01 wrote:
As far as I've observed, it will always send MIDI notes when it plays something on its own synth, whether you're playing on the ribbon, or whether sequencer is triggered internally or externally.

that would be extremely cool! the only other sequencers i'm aware of that give you midi notes triggered by analog trigger signals are the doepfer dark time and the mfb urzwerg pro.
darenager
DGTom - You can sync a stock monotribe to the Leploop using either of the Leploop gate outputs - works great thumbs up
DGTom
darenager wrote:
DGTom - You can sync a stock monotribe to the Leploop using either of the Leploop gate outputs - works great thumbs up


Thats what makes it so appealing grin

I've got the CASSA / SEQ / S&H gates clocking my modular now; pinging Bugbrand SVFs + dirty leploop sequences. . . adding simple drum+bass to that would be love

But; I don't really want to have to clock the whole thing from midi just to have the 2880 synced, clock to MIDI is my dream atm
Veqtor
Well, to try and answer your question, yes I think it will send out midi notes when triggered by the analog sync inputs... nitro, care to verify?
dykehouse
Some unbelievable modifications really opening this bad boy up...nice work!
DBM
nitro2k01 wrote:

Also, keep them ideas coming. If there's enough interest, I might offer kits and/or modification services.

The best thing would be a small midi I/O box ( maybe with USB ) that could just run a cable to the ribbon ....so as far as korg knows the warreny wasn't voided razz

Also I take as you said the monotribe always sends midi out that it would be easy to chain to other synths or another tribe for a 2nd OSC ?
DBM
Btw thanks for your work here I love the sound of it , I just prefer to play with keys . Keep up the great work !
DBM
So as the genie is being pried out of the bottle ....
Questions : As the microcontroller is acting as a midi in and out with it's own built in sequencer I would suppose the synth and each drum are on there own midi channel ....are these fixed ? I would assume so , but if the chip can be told what midi channel to listen to then that would open up other possibilities such as sending a round robin midi notes to multiple units ?
Also the user interface has a preset ENV selection , but is this the whole truth in the code or are there CC's lurking ?

I personally am most interested in just playing this as a mono with keys myself , but curiosity is still always tapping d'oh!
nitro2k01
Yeah, they're probably fixed. Channel 1 for the synth and channel 10 for the drums, the latter being the General MIDI standard. I'd assume there's no way around that, or at least none that is easy to figure out. Also, not sure if it will blindly thru anything that comes in. I think a MIDI router/splitter of some kind would be better for that kind of application.

As for the EG... I can see possibiities.
1) The envelope is generated all in software. In this case there may or may not be other CCs with relation to the EG.
2) It just controls an analog switch which controls analog circuitry in some clever fashion. In this case any further CCs for attack/decay would be unlikely.
bcmonke
Hey guys been reading this forum for a while and finally thought to register... Monotribe is in the mail and I'm really excited.

Now as far as the ribbon controller is concerned, would it not be possible to replace the actual controller or simply wire in a switch to change between that and a device like this?

http://highlyliquid.com/midi-decoders/mpa/

Basically its just a circuit that takes midi inputs from a controller keyboard or whatever, and from what I can see can be made to change the resistance of a loop in real time depends on what was programmed. I'm not saying this one specifically is the best etc... its more an idea.

Could we not just measure the resistance on the ribbon controller for each specific note and then program a board like this to basically take its place? Has anyone used anything like this? How are the response times etc.

I love where the monotribe is going
nitro2k01
bcmonke: Not sure if you've kept up to date on the progress, but the monotribe itself has MIDI support, which is really just a matter of hooking up. See my previous posts in this thread.

Using something like that kit would just be adding unnecessary complexity if you're talking about controlling note data or any of the already automatable parameters. You could use something like that for controlling additional parameters, however, like filter cutoff and the drum decays.
DBM
nitro2k01 wrote:
Yeah, they're probably fixed. Channel 1 for the synth and channel 10 for the drums, the latter being the General MIDI standard. I'd assume there's no way around that, or at least none that is easy to figure out. Also, not sure if it will blindly thru anything that comes in. I think a MIDI router/splitter of some kind would be better for that kind of application.

As for the EG... I can see possibiities.
1) The envelope is generated all in software. In this case there may or may not be other CCs with relation to the EG.
2) It just controls an analog switch which controls analog circuitry in some clever fashion. In this case any further CCs for attack/decay would be unlikely.


Yes more than likely on both of the latter , but hey never know till you ask right ?
All this info should be able to be found running a midi monitor on the out I would think ?
As for sudo chaining two monotribes for a 2nd OSC/Layer .... I thought you had said it sends all midi out all the time ? So if you were playing a note in through a midi in or through the sequencer itself it also sends the note out right , or did I misinterpret ? Either way no big deal as I have a 3x8 midi through box smile
bcmonke
Hah ok then, well, I was more just throwing it out there. I have been following everything closely but if it could be used to control the cutoff etc maybe it might still serve some usefulnesss.
DBM
Any updates ?
@ Nitro
BTW as I understand it your midi mod proposal could be all external - ie: no soldering on the KLM Board itself necessary correct ?
nitro2k01
No updates yet, sorry.

They are all KLM boards. Assuming you mean KLM-3074, the biggest one. (The other ones are called KLM-3075 and KLM-3076. Korg are probably labeling their board designs sequentially. Monotron is KLM-3035 for reference.)

But yeah, if you can find the matching female header, you could do it without soldering. However, that would be of absolutely no help whatsoever, as far as preserving the warranty is concerned. Restoring a solder joint is relatively simple to do, whereas you would need to drill a hole or something equally intrusive in order to route out a jack. But yeah, if you want to make an "internal" MIDI mod without any connection to the world around the machine, I guess you could to that without soldering. :p
DBM
nitro2k01 wrote:
No updates yet, sorry.
However, that would be of absolutely no help whatsoever, as far as preserving the warranty is concerned. Restoring a solder joint is relatively simple to do, whereas you would need to drill a hole or something equally intrusive in order to route out a jack. But yeah, if you want to make an "internal" MIDI mod without any connection to the world around the machine, I guess you could to that without soldering. :p


What they don't know will not hurt them hihi

Nope no interest in building it in to the unit .
nitro2k01
Oh, you mean to remove the ribbon and route the cable out that way? Or drill an invisible hole through the case?

dit: Double oh, or just doing the mod temporarily.
DBM
nitro2k01 wrote:
Oh, you mean to remove the ribbon and route the cable out that way? Or drill an invisible hole through the case?

dit: Double oh, or just doing the mod temporarily.

Current plan is to build a kinda shelf styled bottom and sides that will house two tribes with the bottoms removed and the midi mods just plugging in to the tribes but build in to the DIY housing .
bword
Heyo. New here and glad I stumbled upon this lovely forum. I've been interested in modular for a couple years but could never find a place on the interweb to learn up. So thanks to most of you.

Also, I'm picking up a "MIDI-IF" kit for my monoTRON this week. I wanted to give this link for reference. I'm sure many have seen this but here: http://beatnic.jp/monotron/V2.html

I'm not sure if that page will be tranlated. If not then I'm sure you can paste on the google browser to translate.

It's basically a midi kit for the monotron so one can use a midi controller instead of the ribbon. I would imagine it will work for the monotribe as well.

Thanks again for all the learnin'. I'm sure I'll stick around.

-Brad
bcmonke
Ok I've got another question. I'm still somewhat new to synths and music production so I'm sorry if this is a dumb one.

Is it possible via a mods of some kind to trigger the audio-in to be fed to the filter without having to to trigger the sound with either the sequencer or ribbon controller? By this I mean only having the audio being input directly to the ms-20 filter without being mixed with the other sound. Love the filter... Wish it could be used on it's own...
Veqtor
Just got one! Think I'll try squeezing in an arduino nano, some 555 based lfo's and make a patch breakout. Time will tell.

I wonder if I can strip the midi beat clock by sending the midi through arduino. I would like to have shuffle capabilities so I hope too generate a clock on the arduino and drive the trigger input internally and reset using midiclock stop. Anyone tried combining midi stop and the trigger input yet?
darenager
Veqtor wrote:

I wonder if I can strip the midi beat clock by sending the midi through arduino. I would like to have shuffle capabilities so I hope too generate a clock on the arduino and drive the trigger input internally and reset using midiclock stop. Anyone tried combining midi stop and the trigger input yet?


That seems like a sound theory, you could have the arduino listen for midi clock then use divide by 6 to get 4ppqn and have one of the pins configed to generate a pulse to send to the monotron clock input. You could also use some more pins from the arduino for your LFOs, and maybe other clock divisions. I'd have no idea how to do this but I'm almost certain it is possible.
Veqtor
Yeah, I could probably do LFO's on the arduino... d'oh!

Now to find a box suitable to extend the monotribe on one side so that perfboards, patchbay and added pots have enough space.
darenager
Hammond make some nice die cast alu boxes that could be sprayed to match the Monotribe, are you planning on fixing the box onto it or using a multicore/ribbon and have the box freestanding?
Veqtor
I want to fix it onto it, dremel out a nice hole (one in the case and a corresponding one in the box) to extend one side of the case basically.
nitro2k01
Here we go. More info. wink

http://blog.gg8.se/wordpress/2011/08/14/monotribe-midi-and-me/
mckenic
Great info nitro2k01! Hug

You are King Korg to me anyway! Interested to see where you go - if you add the extra 'duino please post?

thumbs up

Now - someone please start making pre cooked boards so all an idiot like me has to do is solder a few pins!
Sir Ruff
nitro2k01 wrote:
Also, keep them ideas coming. If there's enough interest, I might offer kits and/or modification services.


I have no doubt there'd be a few people here interested in this (inc. me)!
mckenic
Sir Ruff wrote:
nitro2k01 wrote:
Also, keep them ideas coming. If there's enough interest, I might offer kits and/or modification services.


I have no doubt there'd be a few people here interested in this (inc. me)!


thumbs up

Excellent, I didnt spot that!

It's motherfucking bacon yo
pulse_divider
Yeah, put me on the list as well.
nitro2k01
Ok, excellent!

Also, a new video filled with cat hair...
pulse_divider
Sublime!
bword
count me in for a kit.
bword
Guinness ftw!
floris
did anybody make it more modular?
cv and audio in- and outputs for the analog part (vco, lfo, vcf, vca, noise, ribbon)?
i'll def get one if there are such points on the pcb!
stromcat
Just picked up my Monotribe, v.excited to play.

After a quick test though I noticed something I hadn't noticed when I tested it (though this was in a noisy musikmesse hall) - the clicking on the envelopes is really quite bad - not sure if this is a fault!

Anyone else confirm this? Or if this is standard and I somehow missed it, any suggestions on a fix? Tweak a few resistor values?!
nitro2k01
Learn to love the click. Learn to love the click. Learn to love the click. Learn to lo... FUCK!

Yeah, that's just how it sounds. I suspect the synth output is switched after the filter to keep the noise floor down. And that the output of this switch is biased differently than the "neutral" signal. If this hypothesis is correct, this might be fixable with a trimpot for biasing, or so.

If you want to hear the background noise, and the click, more clearly, do this. Turn down the drum level (which has its own noise floor), noise level, filter frequency, LFO intensity and resonance all the way down. Turn the synth level all the way up. Now play a note and enjoy the pure noise floor and click.
cvtele
nitro2k01 wrote:
Yeah, that's just how it sounds. I suspect the synth output is switched after the filter to keep the noise floor down. And that the output of this switch is biased differently than the "neutral" signal. If this hypothesis is correct, this might be fixable with a trimpot for biasing, or so.


That sounds like it is probably what's happening. Now that I read this I think my Monotron also did the click thingy. I'm thinking twice now if I really want a Monotribe.
Nils
Nils wrote:
would a mod converting the mono audio output to a stereo output (tip - synth, ring - drums), be doable/easy? I don't want to modify the housing..


A bump for this one. Anyone care to look into it?
aksen
cvtele wrote:
That sounds like it is probably what's happening. Now that I read this I think my Monotron also did the click thingy. I'm thinking twice now if I really want a Monotribe.

i guess it depends on what you're planning on doing with it. if you're just getting it for a fun toy, the clicking doesn't matter. if you're getting it for music production, it could matter, depending on what you use it for. i've only included the monotribe in one track (here if you're curious), and because of the nature of it (acid techno), the clicking didn't phase me.
nitro2k01
Nils: Pretty much trivially doable. You could just route the individual drum outputs to the tip and ring outputs of the jack. However, you could also make a more sophisticated connection to make it buffered. I'm afraid I can't help you with the details at the moment as I'm abroad and don't have my monotribe (or soldering equipment) with me.
Nils
nitro2k01 wrote:
Nils: Pretty much trivially doable. You could just route the individual drum outputs to the tip and ring outputs of the jack. However, you could also make a more sophisticated connection to make it buffered. I'm afraid I can't help you with the details at the moment as I'm abroad and don't have my monotribe (or soldering equipment) with me.


Thanks! A buffered output would be nice. But isn't there a summed output right after the drums volume knob that could be routed directly to thetip/ring? This would keep the volume function intact as well.
bartleby
somebody calling himself "statikwave" is offering monotribe modding services and premodded monotribes on ebay. is this anyone we know? has anybody here tried his service?

@nitro2k01: any news on your own modding kit plans? [edit:] hm, i just read the comments to your blog post. seems like the simple resistor-only method for midi in is working fine. so i guess there is no need for a kit really. it would only consist of two midi jacks and threee resistors. smile
bartleby
- sorry, double post again. why is the "quote" button on these forums in the exact place where most other forums have the "edit" button? and why am i too stupid to tell the difference? -
nitro2k01
Well, I will still be abroad for approximately another 3 weeks, but my plans remain.
infradead
nitro2k01 wrote:
Well, I will still be abroad for approximately another 3 weeks, but my plans remain.


cancel your vacation and get to werk mayn..
bartleby
infradead wrote:
cancel your vacation and get to werk mayn..

have you read his blog post and the comments confirming that the simpler resistor-only method for midi in is working ok? you don't need a kit do do this, all you need is two din jacks and three resistors (2x 150 ohm, 1x 820 ohm). so go ahead and do it, and let the guy enjoy his vacation. grin
infradead
bartleby wrote:
infradead wrote:
cancel your vacation and get to werk mayn..

have you read his blog post and the comments confirming that the simpler resistor-only method for midi in is working ok? you don't need a kit do do this, all you need is two din jacks and three resistors (2x 150 ohm, 1x 820 ohm). so go ahead and do it, and let the guy enjoy his vacation. grin


oh i don't even have a monotribe.

i'm just harassing a friend grin
bartleby
infradead wrote:
i'm just harassing a friend grin

oh i see. nothing wrong with that, of course. grin
bartleby
has anybody found trigger points for the 3 drum sounds yet?

[edit:] or an fm cv in point for the vcf?
lazenbleep
I found that you can step the sequence from the trigger in using just a piezo.
Attached it to my kick drum.
Its nice.
MrDys
Reminds me of:

lazenbleep
Exactly! Got me thinking too. Might use my micro modular on my snare. Its a really nice feeling hitting the kick and getting a squelch.
jonkeefe
FYI, KORG has released the Monotribe schematics.

Doesn't seem to be a full schematic by any means, but all of our now-well-known patch points are clearly labeled. This is fun!

KORG Monotribe Schematics
nitro2k01
Hmm, only the rhythm section? Means I will have to do some reverse engineering when I get back, after all...
rico loverde
hey guys, i wanna do the bass drum and snare drum mod on mine but im not finding any 2.2k log pots, a friend recommended using a 5k with a 4.7k resistor parallel to it...does this sound right?
nitro2k01
Yeah, that's about right. However, you will get a slightly different response curve. Or you could just use the 4.7k right away and see if you like it. It's not an exact science, and nothing will blow up...
yesusgearfly
Hi guys, just wanted to tell you about a problem I'm having with the monotribe midi mod! I did the "easy" midi in mod but it works just on one masterkeyboard, while it doesn't work at all with my other pieces of gear ( a microkorg and an old yamaha keyboard, psr-195).The problem is that my masterkeyboard always had problems controlling my hardware synths ( it cuts notes, apparently without a cause) and, obviously i'm having the same problem controlling the monotribe! sad banana The strange thing is that the mod works only on my "broken" masterkeyboard, while with the other keyboards it just seems like it is getting no signal at all.. I tried to replace the 1k resistor I used first and used a 820 ohm one but it still doesn't work at all. It's quite strange and I wnated to know if anyone experienced the same problems I0m having and if there is a possible solution to it. I hope this post could be useful to you all and I hope I will be able to fix it, because this is so much important to me! we're not worthy Thank you very much guys!
nitro2k01
Hey. You have left comments almost everywhere. I've been away on vacation, so I haven't had time to answer you. I've answered you on my blog, but I'll paste it here as well for reference.

Quote:
Hello. If the simple method doesn't work, this may mean that the ground pin in the keyboard that doesn't work, is unconnected. Normally it's not needed for MIDI, so maybe they left it out. This fits your description of the problem.

Using the optocoupler version should work if this is the problem. 6n136 is probably better since some people had problems with the 6n138 circuit.

If you want to use the "easy" circuit... Just to troubleshoot, try making a connection between the ground points of the keyboard and the monotribe. For example, connect a wire to the ground screw and touch it to a ground point of the keyboard, or something connected to the keyboard. For example, touch the wire against the shielding of a USB plug or the "sleeve" of an audio cable coming out of the keyboard. Or if the keyboard is connected to a computer, add a second USB cable and touch the shielding to ground screw of monotribe. And see if MIDI works when you do that.

However do not assume that the outer part of the power plug (ring) is ground, unless you check that the adapter is center positive. If it's center <b>negative</b>, the ring is positive, and connecting monotribe ground to the positive power, when using the easy circuit, may damage the monotribe.

If it works when you do this, then I can try to figure something out.
yesusgearfly
Sorry I didn't want to be annoying but thank you very very much for your answer! we're not worthy I was just worried I broke something since I don't understand a f***k of circuitry very frustrating ! However , today I'll try some different configurations and the keep you updated about the progressions! Thank you very much Nitro!
fleetway76
This thread has been dormant for a while so this might kick it back into action. Did anyone come up with any interesting mods for the monotribe since the schematics came out? I managed to get useful mods for the bd decay and sd frame decay but I am struggling to get anything useful from the noise decays other than cutting them down to very short bursts.
algorhythm
Yeah, interested in this too - it's all very tempting for the price. Although, I suspect we'll see lots up for sale used soon enough... speaking of, I see someone on eBay offer mod services... anyone try that route?
jonkeefe
Fleetway, have you tried connecting SD frame decay and SD noise decay to the same pot?

I'd also be interested in hearing samples from your mods so far... any chance of a youtube video?

I've been preoccupied with modding my Monotron for the past while, but once I get that project finished (hopefully within the next week or so), I'm gonna tackle the Monotribe -- definitely separate drum outputs and MIDI, maybe drum decays based on whether I think it's worth the effort smile

I just realized I really shouldn't have paid an extra $10 for the extended warranty, since I plan on voiding the *original* warranty as soon as possible... d'oh!
algorhythm
D'oh! What sort of mods are you thinking? There are some cool ones online: http://www.youtube.com/watch?v=dF8skIOXp24

Love the lil' MS-20 mod. thumbs up
jonkeefe
For the monotron? I've already added MIDI-in, glide, replaced the onboard pots with panel-mount ones, and I'll be adding the LFO-EG mod, 1/4" jacks, and separate on/off and lfo target switches next week. smile

It seems like there are a lot less people modding their 'tribes so far, but to be fair the 'tron has been out for much longer!
nitro2k01
This is not the big MIDI update everyone is waiting for, but I did a write-up on syncing the monotribe to LSDj (Gameboy music software) using the sync jack:

http://blog.gg8.se/wordpress/2011/09/28/syncing-monotribe-to-lsdj-usin g-the-sync-jack-no-midi/
yesusgearfly
what about adding PWM? Is it possible in your opinion? SlayerBadger!
bartleby
somebody in brasil is already selling midi kits:

http://www.ebay.com/itm/170712639260

75 + 24 usd seems a bit steep though.
D_Bowman
wow that is a bit steep indeed. But tempting for those of us with no soldering experience. thanks for the tip.
th0mas
bartleby wrote:
somebody in brasil is already selling midi kits:

http://www.ebay.com/itm/170712639260

75 + 24 usd seems a bit steep though.


WHAT

That is a ripoff. It's maybe 5$ in parts.
nitro2k01
Supply and demand... If you're first on the market and have no competition, you can choose your prices freely. That's just how a market works.
I'd recommend the eBay guy over the Brasil guy. Only problem there is that we don't know for sure whether he's legit.
th0mas
nitro2k01 wrote:
Supply and demand... If you're first on the market and have no competition, you can choose your prices freely. That's just how a market works.
I'd recommend the eBay guy over the Brasil guy. Only problem there is that we don't know for sure whether he's legit.


yup. thankfully my CNC's almost finished so I can race this guy to the bottom.
aksen
nitro2k01 wrote:
I'd recommend the eBay guy over the Brasil guy. Only problem there is that we don't know for sure whether he's legit.

a wiggler has had his monotribe modded by the ebay guy and said the quality was great (hope you don't mind me saying that jcn7 smile ). that was good enough for me to take the plunge on it as well, though i'm still waiting for mine to return to me.
rico loverde
Anyone find a mod that allows you to separate the ext audio input of the mo tribes synth. I'd love to be able to run audio thru the filter while using the drums but not the synth voice. Doubt this is possible but thought I'd ask...
neilbaldwin
To save me reading all 8 pages, is it possible (via modification) to trigger the drums via CV/gate input rather than MIDI control?
nitro2k01
neil: Don't know if it's been mentioned in the thread, but yes. Get the schematic and look for the part where an inverter is connected to a capacitor. On the right side of any given capacitor, connect a capacitor of the same value. Apply a +5 V gate/pulse to this capacitor to trigger that drum part in parallel with the 'tribe's own triggering mechanism.
jcn7
Hi...yes I had one of my units modded from the "Ebay Guy" :

(http://www.ebay.com/itm/Korg-Monotribe-MIDI-I-O-Drum-Outputs-Decay-MO D-Service-/140593361815?pt=Keyboards_MIDI&hash=item20bc047397)

I have been quite pleased. He's very nice to do business with by the way, and his work is quite professionally done...hope that helps!
10011001
nitro2k01 wrote:
This is not the big MIDI update everyone is waiting for, but I did a write-up on syncing the monotribe to LSDj (Gameboy music software) using the sync jack:

http://blog.gg8.se/wordpress/2011/09/28/syncing-monotribe-to-lsdj-usin g-the-sync-jack-no-midi/


GB sync would be wicked but somebody needs to do this via a GB cable instead of an audio channel
nitro2k01
10011001 wrote:
nitro2k01 wrote:
This is not the big MIDI update everyone is waiting for, but I did a write-up on syncing the monotribe to LSDj (Gameboy music software) using the sync jack:

http://blog.gg8.se/wordpress/2011/09/28/syncing-monotribe-to-lsdj-usin g-the-sync-jack-no-midi/


GB sync would be wicked but somebody needs to do this via a GB cable instead of an audio channel
You could already do that with MIDI out from the 'tribe and ArduinoBoy. ArduinoBoy+a special version of LSDj even lets you use LSDj a MIDI sequencer, which should give you full control of the 'tribe from the Gameboy.
oberkorn
am I doing something wrong here?, started with the MIDI mods and cannot get it to work. maybe I'm just tired... heres is what I did (quick mspaint sketch!)


comments/corrections more than welcome!
A Dingleberry Monstrosity
th0mas wrote:
bartleby wrote:
somebody in brasil is already selling midi kits:

http://www.ebay.com/itm/170712639260

75 + 24 usd seems a bit steep though.


WHAT

That is a ripoff. It's maybe 5$ in parts.


same thing can be said for 90% of all the modules out there that cost hundred and hundreds of dollars...
nitro2k01
Oberkorn, yes, you've done something wrong. Gnd is always pin 2 on MIDI out, and also for MIDI in in the simple method. So that's the first error. On MIDI out you have swapped 3.3V and the signal.
mckenic
Just cracked mine open - looking to do simple midi-in to get up and running (before drum & wav outs hopefully!).

Using Oberkorn pic above for midi-in to the Monotribe its - Pin 5 (via 820ohm resistor) to rx & Pin 2 to ground... would this be correct please?

Rather than soldering anything directly on to the pcb yet (CN13), can I hook-up to the serial header (CN12) if I can find the right connector etc? That the same thing?

Thanks folks - VERY excited!!!

Woo Hoo!!!
drewtoothpaste
An individual out of an MPC set to a short-decay squarewave/pulse or a chopped drum hit works great for sync & lets you put the notes where you want them instead of on a straight eighth-note grid...

8_)
MrDys
Anyone know if it's possible to get the synth section and drum section to run at different tempos? It's being sync'd from my MPC, and ideally I'd like the synth to run at half speed of the drums. I could program half the notes for the synth, but that kinda sucks since the sequencer is only 8 steps to begin with.
nitro2k01
mckenic: Yes, that description sounds correct. CN12 and CN13 are different. CN12 is the one you'd use for MIDI, whether you solder to the back of the connector or find the right matching female connector. I simply described in my post what I did and found the most easy to do. A female connector would be preferred.

MrDys: The drum section has 16 steps. Hold down the corresponding drum button and use the sequencer steps in order to access these steps. These steps are located after regular steps, so if you hold down BD and press 1, you'll activate a bass drum hit between 1 and 2. The monotribe still only receives 8 sync pulses per loop turn and instead interpolates the extra steps between the regular ones. It does this rather stupidly based on the time between the two last pulses. If the beat of the incoming pulses is irregular or heavily shuffled, it can actually miss extra drum hits at times when there's first a long time between the pulses and then a short time.
mckenic
Many, many, many thanks for your time nitro2k01! thumbs up

I'll let ya'll know how it goes! Excited hyper
Lento_Zoom
Did the midi-in on Saturday night. Works like charm with my esq-1. If anyone gets part number on that female serial connector, please share. I will keep looking my self and will pass along what I find. I cant get over how the midi brings this thing to a whole new level.
computer controlled
Lento_Zoom wrote:
Did the midi-in on Saturday night. Works like charm with my esq-1. If anyone gets part number on that female serial connector, please share. I will keep looking my self and will pass along what I find. I cant get over how the midi brings this thing to a whole new level.


Pics? I'd like to MIDI up mine asap.
Muff Wiggler
Very cool
Lento_Zoom
Here are some pics of my build. I just soldered to the pins on the serial connection. I think I'm going to make a midi out and through in the same box. Super easy and cheap to DIY.
Lento_Zoom
And the bottom...
Lento_Zoom
Inside the box.
Lento_Zoom
And a very dirty job on the bottom of the the board...
mckenic
Can someone check this for me please?

Im obviously doing something ass-ways!



Red to Midi-In, Blue to Ground.
Now the not so nice part thats prolly the problem... I dont have a midi connector at the moment so to get up and running I soldered directly to a spare midi cable.


Continuity test works from the bare wires (on the Monotron side of the Midi cable) to the male connector on the Monotribe. Ground works from the Tribe pins, all the way to the ground on the Midi cable but continuity stops at the resistor... dont know if thats the problem...

Any help VERY appreciated!
nitro2k01
You should not get continuity through the resistor. It is not a conductor, but blocks current to some degree. You should get continuity between one end of the resistor to the other end of the cable. And from the other end of the resistor down to the board. Same is true for the gnd lead, there should be continuity from the pin on the other side of the MIDI cable, all the way to any ground point on the 'tribe. You seem to have connected things in the right places.

There's the possibility that your MIDI interface doesn't have the ground pin of its jack connected. Try testing continuity all the way from ground on the 'tribe, to some ground point like the shielding of a USB jack on the interface.
mckenic
Thanks very, very much for all your help & patience nitro2k01 mate!

There are HUGE holes in my DIY knowledge and I think Imna give up with the 'tribe at this stage - Im a little disappointed with myself really. Plague Barer kits/Arduino stuff/SammichSID etc. fine - here Im lost.

I went from ground on the male pin in the 'tribe to the sleeve of a guitar lead plugged in to my Ultralite and got continuity. On the 2k setting on my meter - I measured from the male RX pin on the tribe to the furthest MIDI pin (past the resistor) and got .810... so it all looks fine but nada seriously, i just don't get it

Very frustrating but there it is! Thanks again for your patience mate Hug
DBM
Lento_Zoom wrote:
If anyone gets part number on that female serial connector, please share.


+1 . I am about to finally do my mod and this is the way I want to go too .

@Lento_Zoom
Nice paring ESQ-1/Monotribe - BTW
Matty
I'm new on here but felt I had to sign up as this forum has been a wealth of help and knowledge with my own project smile

Not long after getting my Monotribe I took the decision to add Midi as a bit of fun. However I didn't fancy making holes in the case or doing anything that would make it look like it had been added too. Wireless looked the way to go. Luckily many people all over the world have been experimenting and it was, armed with this knowledge I set about adding a wireless serial connection. The cost was not that high considering what it can do and the parts are readily available over the net from eBay and such.

I have gone down the Xbee/clones route and found a small company that makes equivalents to the Xbee for about a tenner each, so two of those plus a USB device to use one plugged into my PC cost around £40. I bought a couple of breakout boards to mount one nicely in my monotribe and found a supplier in HK that sells the serial connectors that fit inside.

I have what I consider, basic electronics knowledge yet was able to assemble in an afternoon quite a nice looking installation. I plan to make an actual hardware midi box as well, that way I won't have to use my PC for all the midi connections.
Matty
If anyone would like to know exactly what parts I used I can post on here, although pretty much everything was found using eBay and sourced within a few days.

In the meantime here is a picture smile
Matty
I have been asked where I got hold of the serial connector. They are a perfect fit and come already wired and tinned with solder. You can either search eBay for "Micro Mini.JST 2.0 PH 6-Pin Connector" or use the following URL.

http://www.ebay.co.uk/itm/Micro-Mini-JST-2-0-PH-6-Pin-Connector-w-Wire -x-10-Sets-/170727183989?pt=Radio_Control_Parts_Accessories&hash=item2 7c0221675#ht_1943wt_689

The supplier is in Hong Kong so delivery takes at least two weeks most places.

For those of you who maybe interested in adding a wireless serial connection for using MIDI with your Monotribe I have started a blog. It contains a full parts list and instructions with pictures.
http://blackb3ltjones.blogspot.com/

** Blog has just been updated with a better layout and hopefully clearer instructions **
yesusgearfly
Hi guys, I'm building my own modbox right now, I'm gonna post photos and audio really soon (midi I/O, individual outs, drums decay + monotron midi as a 2nd oscillator). Just one curiosity... I read in this thread that low-gain has found wave outs, did anyone test them? I would be really interested in knowing waht could this mod give to the product, and how could it be used! thank you very much and thanks again tyo Nitro , even if he hates me! Dead Banana
jenamu6
I can't find it....but is it possible to have the sequencer spit CV out?
bartleby
korg have announced a v2 firmware update for the monotribe. promises some useful new features like 16 steps for the synth track and independend "active step" settings per track.

has anybody tried this? i hope it doesn't break the monotribe's midi capabilities?

[edit: tribalized the trons - thanks aksen]
aksen
i think you mean the monotribe wink i've upgraded mine, and the midi still works fine.

on the new features - the sample and hold is a nice addition, and the only one of interest if you're just triggering it via midi. if you still use the internal sequencer (and i do for fun/mucking around) - the separate active steps per voice is neat, being able to set volume per step on the synth is nice. the drum roll feature i find has limited appeal - without being able to control an individual drum sound's volume on the tribe itself, it's a little machine-gun-like in operation (i only found it worked acceptably for the hats). being able to clear all pattern data instantly is also useful.

interesting that the way to update it is to play an audio file into the sync in port - obviously they had planned this sort of thing from the beginning.
MrDys
Seems somewhat useful, I guess. I really would have liked if they would have included a "Randomize sequence" function instead of/in addition to all of the "Initialize sequence" functions.
yesusgearfly
The only difference I noticed is that the monotribe is now reacting to velocity variations! This is cool and probably depending on the "volume per step" function wink I quote Aksen: the sample and hold is really fine, but if you use midi the other functions are quite useless!
darenager
A cool update, the individual track lengths is a lot of fun -polyriddims!

Bonus points to the first clever chap to reverse engineer the update wav file and add more features lol
th0mas
darenager wrote:


Bonus points to the first clever chap to reverse engineer the update wav file and add more features lol


working on decoding it back to a binary file right now smile
yesusgearfly
Wondering if they could add some options to modify the envelope generator in the future, this sounds pretty much doable
radiokoala
Well, I updated but S&H doesn't work for me hmmm..... It is written that LFO wave switch has no effect when S&H is on, but for me it has either way, and I'm hearing it. Drum rolls, 16-step sequencer, and all that stuff work at that... Also, in update instructions MONOTRIBE_SYS_0201.wav file is mentioned and in an archive I downloaded it is *.m4a. WTF!

Upd. All works fine now. :]
DBM
So I can only assume there may in theory be a way to dump data out of the tribe as well ... Patch , seq , os/sysex ?
For the coders out there it would then also seam that the os is hackable and any thing the arm is connected to could in theory be hacked .....
Auto tune , pw ? , lfo and env code .
+ it can now send start stop through audio no ? Hmmmmmm
DBM
Interesting stuff
MrDys
th0mas wrote:
darenager wrote:


Bonus points to the first clever chap to reverse engineer the update wav file and add more features lol


working on decoding it back to a binary file right now smile


Let me know where you get with this. I have a month of vacation starting in 4 hours, and hacking the monotribe software sounds like a good use of my free time.
StepLogik
th0mas wrote:
darenager wrote:


Bonus points to the first clever chap to reverse engineer the update wav file and add more features lol


working on decoding it back to a binary file right now smile


It is very cool to know that the MonoTribe can be so easily reprogrammed!

After you get a binary file, then what? Based on the type of CPU, you might be able to download the Dev tools for it and at least get some information from the file. I'm guessing it is some type of ROM image or something? Even better is if it can be decompiled into something at least vaguely human-readable.

Maybe Korg would just send us the C code? This is fun!
radiokoala
For y'all, Korg Monotribe 2.0 checkup.

[s]http://soundcloud.com/radiokoala/gastroenterology-of-mollusca[/s]
It is called Gastroenterology of Mollusca...

screaming goo yo SlayerBadger!
th0mas
radiokoala wrote:
For y'all, Korg Monotribe 2.0 checkup.

[s]http://soundcloud.com/radiokoala/gastroenterology-of-mollusca[/s]
It is called Gastroenterology of Mollusca...

screaming goo yo SlayerBadger!


for a second I wasn't sure if this was a recording or an upload of the firmware update wink

I'm getting.. somewhere. I have it encoding to *a* binary file but i'm hoping for a magic number near the start or some logic to the file and I have none yet. I can decode the waveform well, basically there's two different length squarewaves (long and short) and I'm assuming they denote a 0 and a 1. Figuring out the bit order and then all the possible offsets is what I'm currently working on. I think I'm just going to generate all the possible options for order / offsets and then strings 'em all and save myself some time... will report back.

EDIT: THIS WORKED: I now have "KORG SYSTEM FILE". I will be uploading the method to generate this soon. I cannot upload the firmware file itself, however, I will document how to do it. Consider it the barrier so that only those willing to brick their monotribe can play smile
darenager
Dang you don't hang about do you lol
th0mas
For those interested: here is the instructions for decoding the firmware file.

http://gravitronic.blogspot.com/2011/12/decoding-korg-monotribe-firmwa re.html

I have not looked at it in detail yet but that's next, obviously.

Not uploading the firmware file for copyright reasons.

edit: I haven't even updated my own monotribe yet hihi
darenager
applause
th0mas
welp.. looks like the file's a series of ~256 bytes broken by ~64 bytes of 0xFF, probably to give the monotribe time to catch up flashing if needed. I'm hoping that those packets have an address and CRC, so decoding those gets you the actual memory map of the device

.. but time to close my laptop and Guinness ftw!
bartleby
th0mas wrote:
working on decoding it back to a binary file right now smile

th0mas wrote:
EDIT: THIS WORKED: I now have "KORG SYSTEM FILE".

th0mas wrote:
I have not looked at it in detail yet but that's next, obviously.
Enjoy the show! i have a feeling i might be following this thread more closely for a while. Enjoy the show!
nitro2k01
I'm late to the party! I originally intended to try to dump the original firmware through JTAG, but I didn't try it yet. (It's possible they have protected the memory in the chip so you can't read it out with JTAG.) I might still want to do that, to have a copy for whatever reason if possible.

And also because it is possible the new firmware is more "secure" against upgrades. For example, they may have added cryptographic checks or something else, so you can't upgrade to anything but official firmwares once you upgrade. Actually, the update manual mentions this: "Check the current system firmware. If it has been updated already to version 2.0, you will not be able to update again (it will also be unnecessary)." I don't like the sound of that... sad banana
They may have anticipated that someone might try to fiddle around with the firmware if given the chance.
bartleby
nitro2k01 wrote:
"Check the current system firmware. If it has been updated already to version 2.0, you will not be able to update again (it will also be unnecessary)." I don't like the sound of that...
are we being a little paranoid? grin
i think what they mean is that you don't need to uplodad this particular firmware update if the unit already has v2.0 installed. but then, you never know. wink

[edit:] but trying to get a backup of the original fw version does sound like a cool idea of course.
nitro2k01
It's the wording I'm concerned about: "will not be able to..." If that's not what they meant, wouldn't it make more to word it something like "Once you've successfully installed version 2.0, you do not need to install it again."

Maybe I AM just being paranoid, but the reasoning for this update could be that 2.0 actually contains all the features that monotribe was supposed to have, but they didn't get everything done in time. Thus they now disable further updates.

Could someone who has updated to 2.0 please try doing step 1 described in the PDF and see if the LEDs still blink as described?
(Hold FLUX/HH/STEP 1 on startup. Confirm that SYNTH, BD and SN are blinking.)
radiokoala
nitro2k01 wrote:
Could someone who has updated to 2.0 please try doing step 1 described in the PDF and see if the LEDs still blink as described?
(Hold FLUX/HH/STEP 1 on startup. Confirm that SYNTH, BD and SN are blinking.)

They don't blink for me dude (hides)
Dirk95100
radiokoala wrote:
nitro2k01 wrote:
Could someone who has updated to 2.0 please try doing step 1 described in the PDF and see if the LEDs still blink as described?
(Hold FLUX/HH/STEP 1 on startup. Confirm that SYNTH, BD and SN are blinking.)

They don't blink for me dude (hides)

Same here.
When I Hold FLUX/HH/STEP 1 on startup, only the step 1 led blinks a few times and I can´t upgrade.
cry
nitro2k01
radiokoala, when you've held the buttons, does unit boot normally and is usable, or does it still seem like it's waiting or something?

Dirk95100, just to clarify, have you upgraded, or are you still on 1.0 you're getting this behavior?
Dirk95100
nitro2k01 wrote:
Dirk95100, just to clarify, have you upgraded, or are you still on 1.0 you're getting this behavior?

Still on 1.0

It is one of the second production batch.
nitro2k01
Dirk95100, are you are on 1.0? Did you just assume it, or did you check it by holding PLAY and GATE TIME on startup? (Several LEDs will light up. If play is lit, 1.0. If rec is lit, 2.0.)
nitro2k01
On a different note, can someone confirm what someone implied earlier in the thread, that the new upgrade also makes it react to note velocities over MIDI?
radiokoala
nitro2k01 wrote:
radiokoala, when you've held the buttons, does unit boot normally and is usable, or does it still seem like it's waiting or something?

No, it is unusable. The same stuff happens, as desribed in Dirk's post. Several blinks and after that unit produces no sound. After pressing power button once again it turns on (and not off as it would, be it powered on).
nitro2k01
Before we jump to too many conclusions, could the both of you please check/confirm that your batteries are fresh? Maybe it detects if the batteries are low and refuses to go into firmware update mode if that is the case.
radiokoala
Wow, I took off batteries from my casio, and it worked!! (It never hurts to have a lot of battery-powered instruments, does it? hihi)
nitro2k01
Phew! I nearly sent an angry letter to Korg's support department.

But I'm still paranoid. Are you absolutely sure that you run 2.0 and that it started blinking?
radiokoala
Yup. Synth, BD & SN lighted up.
Veqtor
Yes, I can get it to go into upgrade mode after my 2.0 update.
Dirk95100
nitro2k01 wrote:
Dirk95100, are you are on 1.0? Did you just assume it, or did you check it by holding PLAY and GATE TIME on startup? (Several LEDs will light up. If play is lit, 1.0. If rec is lit, 2.0.)


It was the bateries, never even crossed my mind to replace them.
Now I upgraded to OS 2.0 SlayerBadger!

Thanks for helping me.
th0mas
Most likely each block is crc'd and that's it.

A cryptographic checksum would be too slow for the Monotribe to calculate and keep up with flashing.
nitro2k01
th0mas wrote:
Most likely each block is crc'd and that's it.

A cryptographic checksum would be too slow for the Monotribe to calculate and keep up with flashing.
Yeah, "cryptographic checksum" was really an acronym for "weak-ass security by obscurity" and it was all speculation. I somehow got paranoid when I saw that sentence. And then these people's 'tribes wouldn't go into update mode. If Korg would've wanted to close this route for upgrading the firmware, they could've easily done that. But all's good in Kansas.
th0mas
I SEE PATTERNS screaming goo yo

There's blocks of 0x106 bytes separated by padding of 0x2B bytes of 0xFF.

The start of the blocks look like this:
Code:


0x826:  ffff 7fa9 0000000000000000
0x957:  ffff bfd4 41fc108841fc1090
0xa88:  ffff 5faa 903c449c01fc4cff
0xbb9:  ffff 2f75 2bf66009404443ce
0xcea:  ffff 971a 3012a042f90b3032
0xe1b:  ffff 4b5d 31d2881510519953
0xf4c:  ffff a562 fc4ee2abc348e505
0x107d: ffff 5203 0200f1b521e08e28
0x11ae: ff   7fa9 274c284f40f2ff1a40
0x12df: ff   bf54 827888058012827584
0x1410: ff   5f2a c13a82c06cfddf1fca
0x1541: ff   2f15 2a000004a2b6610934
0x1672: ff   974a 00afc10bd70bf00b15
0x17a3: ff   4b25 305aeb5b8a05000931
0x18d4: ff   a502 42018018c0cfe29780
0x1a05: ff   52b1 c30acde18e007ea102
0x1b36:      7fa9 801002f0010404430ad0
0x1c67:      bf54 801302f8808302a38f58
0x1d98:      5f2a 161ed49026de361ed410
0x1ec9:      2f15 c17f8c6f27b6005ebf3f
0x1ffa:      97aa 0907778419000082a114
0x212b:      4be5 6cd454039425d808c197
0x225c:      a5fa dfa3fd0ea814444fe227
0x238d:      526d a035f9045466a0379426



The end of each block looks like this:
Code:

0x7f7:  0000aaaaaa fcffff
0x928:  3122555555 0bffff
0xa59:  0da4aaaaaa a9ffff
0xb8a:  165e555555 efffff
0xcbb:  e3b7aaaaea f8ffff
0xdec:  4050555565 f6ffff
0xf1d:  86a8aaaa3a ffffff
0x104e: a85755559d feffff
0x117f: 9caaaaaa1c ffffff
0x12b0: 4655555564 ffffff
0x13e1: 86aaaaaa97 ffffff
0x1512: 6f555595ee ffffff
0x1643: a8aaaa8af2 ffffff
0x1774: 545555b5fa ffffff
0x18a5: afaaaab2ff ffffff
0x19d6: 54555571fc ffffff
0x1b07: abaaaad0fe ffffff
0x1c38: 55555548ff ffffff
0x1d69: aaaa2ae1ff ffffff
0x1e9a: 555595ffff ffffff

See the patterns?

There's occasionally a block that is 1 byte shorter, which is why the alignment shifts 1 byte to the left every 8 blocks.

Anyways.. might be easier to just dump the firmware somehow like JTAG. This is interesting but I have 0 indication what I'm doing is correct. The next thing would be to look at the data and see if it resembles sensible ARM assembly.
nitro2k01
I'm looking at this as well, and I'm seeing one more pattern than you do. wink
Quote:
There's occasionally a block that is 1 byte shorter, which is why the alignment shifts 1 byte to the left every 8 blocks.
This is almost correct. Rather, I believe it shifts 1 bit every block. The clues?
1) Look at the last bytes in each block. Every second block ends with AA AA AA and the other with 55 55 55, i.e. the classic checkerboard patterns, 5=1010 and A=0101.
2) Look at the (apparent) first byte of different blocks.
00: 52 (This is probably correct.)
01: 7f (Notice how this number is special in that it has the 7 lowest bits set)
02: bf (6 lowest bits set)
03: 5f (5 lowest bits set)
04: 2f (4 lowest bits set)

Starting to see the pattern? The bits are shifted in from the lowest bit of a byte (I'm assuming). So if you insert a bit in every block, a 1 bit will be shifted in at the bottom of every one of these start bits and each of them will turn into a ff. Exactly where this extra bit should be correctly inserted, I'm not sure, but it seems like I'm onto something here.

To be continued...
StepLogik
The Toshiba CPU in the MonoTribe has the ability to secure the ROM software so that it can't be dumped via JTAG. Hopefully Korg didn't enable the protection bit!

That CPU also has a user boot mode that allows the ROM firmware to be updated. I'm guessing that is the Korg upgrade procedure. The new program can be uploaded via a standard I/O pin, which I would imagine the sync jack is connected to via a buffer.

The data format for the upload is described in the spec sheet, you might be able to correlate to your reverse-engineered data file.
radiokoala
BTW what is the clock speed of Monotribe's CPU? (Just curious.)
th0mas
nitro2k01 wrote:
I'm looking at this as well, and I'm seeing one more pattern than you do. wink
Quote:
There's occasionally a block that is 1 byte shorter, which is why the alignment shifts 1 byte to the left every 8 blocks.
This is almost correct. Rather, I believe it shifts 1 bit every block. The clues?
1) Look at the last bytes in each block. Every second block ends with AA AA AA and the other with 55 55 55, i.e. the classic checkerboard patterns, 5=1010 and A=0101.
2) Look at the (apparent) first byte of different blocks.
00: 52 (This is probably correct.)
01: 7f (Notice how this number is special in that it has the 7 lowest bits set)
02: bf (6 lowest bits set)
03: 5f (5 lowest bits set)
04: 2f (4 lowest bits set)

Starting to see the pattern? The bits are shifted in from the lowest bit of a byte (I'm assuming). So if you insert a bit in every block, a 1 bit will be shifted in at the bottom of every one of these start bits and each of them will turn into a ff. Exactly where this extra bit should be correctly inserted, I'm not sure, but it seems like I'm onto something here.

To be continued...


I realized the 55's and AA's were alternating bits but didn't put it together with the 1 byte shift per 8 blocks as I just found that before posting.

Adding a bit at the end of every 0x28 FF block makes the data look normalized but incorrect (the second KORG disappears). Looks like it needs to go in, but somewhere else in the block.

edit: getting somewhere.. if you add a bit to all but the 1st two blocks you end up with another KORG SYSTEM FILE string at 0x7900 in the file. Don't have time to investigate if the rest of the file looks better.
StepLogik
radiokoala wrote:
BTW what is the clock speed of Monotribe's CPU? (Just curious.)


According to the spec sheet it can run a max of 40 Mhz. It has a low power mode that slows the clock down and i guess that is probably used when running from batteries.
th0mas
updated python script on github does my current best-effort at decoding (including extra bit insertion)

Guinness ftw!
nitro2k01
Tada!
http://blog.gg8.se/wordpress/2011/12/04/korg-monotribe-firmware-20-ana lysis/
th0mas
nice work!

Based on your decoder I figured out the checksum. You sum all data bytes of the packet and mod by 256 and that's equal to the checksum byte.

edit: tried disassembly with a random ARM cross-compiler I have installed and this technique http://askrprojects.net/software/objdump.html didn't look right to me but im just glancing
StepLogik
we're not worthy Awesome work, gentlemen!
nitro2k01
th0mas: This micro has a Cortex-M3 core, which means it only supports the Thymb/Thumb-2 instruction set, and not regular ARM set. This means it's sort of incompatible with the general ARM architecture. (If I've understood things correctly.) You may need to indicate this to objdump somehow.

Also, you don't know where the entry point is or if it starts with 16- or 32-bit code. I'm suspecting some of the first value may be pointers. 0D010000 (or 0000010D when corrected for endianness) points to right after a block of FFs.

We'll see...
th0mas
did not realize cortex only supports thumb.

thumb is all 16 bit instructions, and a histogram shows much more reuse of data at 16 bits than 32 bits so that seems correct.
nitro2k01
Thumb is all 16-bit, yes, but thumb-2 has 32-bit instructions as well.
bartleby
i just tried to do the midi mod - with mixed results:

midi out:
this works fine with only one limitation: the tribe sends notes also for those steps that are set to 'off'. it does ignore the note number information for those steps, but it repeats the previous note instead. is this normal?

midi in:
i can't get this to work at all. i don't have an optocoupler at hand, so i tried the simpler 820 ohm resistor method - which seems to work fine for a lot of people. but it doesn't work for me at all. i tried different resistor values, but that doesn't change anything. the tribe completely ignores incoming notes. instead, whenever i connect just anything to that rx pin, the tribe starts going crazy - the sequencer occasionally missing some steps or resetting before the loop is finished, the synth playing some weird sounds from time to time, sometimes the whole unit will just freeze completely. any idea what might be wrong there?

any help would be much appreciated...

also, has anybody found a way to silence the internal oscillator when using external audio?
bartleby
[double post - please delete]
darenager
^ Did you make sure to have ground connected? What are you driving it with?
bartleby
darenager wrote:
^ Did you make sure to have ground connected?

yes, i had pin 2 of the midi connector connected to the gnd pin of the tribe's serial header, and pin 5 to the rx pin thru a 820 ohm resisitor, just as described in nitro2k01's blog post.

you think the problem might be a bad gnd connection? will recheck when i get back from work this evening..

darenager wrote:
What are you driving it with?

i tried two things: a sci multitrak as keyboard and a no-name usb midi interface + camera connection kit with my ipad.

the midi signals from the multitrak didn't seem to have any effect on the tribe at all. the ones from the ipad/usb interface did occasionally trigger some weird notes with no recognizable relation to what was actually being played...
Altitude909
You should really use an opto for this. There is a very good reason that ALL midi inputs on ALL midi devices use them. Keep in mind that the monotribe runs on 3.3V, most midi devices are 5V. Technically you could get it to work but you could be messing with values for a while to dial it in and possibly damage something in the process. I just used an fairchild 6N137, a 10K pull up and it worked perfectly
bartleby
i guess you're right, i better get me one of those opto things. it just seemed that everybody else was getting it to work with the simpler method, so i thought maybe i was overlooking something.
darenager
Mine is working great with a 820r resistor, tried running it from Moog LP and Machinedrum both with no problems, an opto is a better way to do it though and I will do this eventually.
mckenic
Couldnt for the life of me get the resistor method to work. With logistics & ordering parts on-line/minimum orders etc. I got an Amazing Machines kit. Arrived today and I updated to v2 lastnight...

Should be a FUN evening hyper
bartleby
mckenic wrote:
Couldnt for the life of me get the resistor method to work

i'm glad to hear it's not just me. i just ordered a 6n136 - let's see where that gets me.
computer controlled
What i want to know is how to get rid of the envelope click.
bartleby
learn to love it? smile
darenager
computer controlled wrote:
What i want to know is how to get rid of the envelope click.


Probably a small capacitor on the trig line to the VCA - but hell knows where that is lol

A note on the simple midi method - when a midi cable is connected some noise is introduced to the output, so an opto isolator is really recommended.
Matty
That Amazing Machines Kit really is a horrendous price for what it actually is, I'm not usually one to complain about new developents, but charging almost half of the real cost of a Monotribe for $10 worth of parts is just plain criminal in my estimation :( Hence the reason I went the wireless route for midifying my Monotribe. No holes to drill and if I ever want to remove the installation I can just unplug the serial connector. I too am enjoying the new ver 2.0 of the Monotribe firmware, lets hope Korg decides to keep it updated with any bug fixes.

Very interested in the development of a home brew firmware. Now that we have a back-up in the version 2.0 download file it should mean we can experiment away without bricking the Monotribe? as I'm guessing any update leaves the boot loader code well alone?
bartleby
Matty wrote:
That Amazing Machines Kit really is a horrendous price for what it actually is

+1 - especially since it's only midi in! to me midi out seems much more relevant - i really like the tribe's internal sequencer and only wish it had more memory slots than just one - and wouldn't send midi notes for steps that are set to 'off'. still, it's great fun using it for sequencing external synths...
darenager
I don't think $75 is too bad, when comparing to things like synhouse midijack, kenton retrofits, asol mod kits. Sure the actual value of the parts is probably about $20 but you are getting a plug and play solution, no soldering or special tools or your time required. I don't think he is aiming it at DIYers so for some people its an easy way.

And as said before pretty much anything electronic only costs a fraction of the retail price in parts, but then you are not buying just a bunch of parts, its a finished product. The monotribe itself is probably less than $40 in parts, especially in the volume that korg buys them, but then some people were moaning about the price of the monotribe too seriously, i just don't get it

I'm not connected to the guy in any way, but it seems that often the subject of price comes up, and if all these wonderful products only sold for their parts cost plus a few dollars, well then there would not be many people making this stuff. I doubt any of these small manufacturers are living a champagne lifestyle.

Back on topic midi in is very handy for accurate realtime note entry into the synth sequencer, you can also record pitchbend if you turn on flux mode.
nitro2k01
Darenger, for any product, you're not just paying for the materials, but also for R&D, manufacturing and for a profit that can be used to finance future projects. For the monotribe itself, I'm guessing a lot of engineers' man hours went into all the aspects of the design. Same with most synth modules.

However, in this case, what justifies the price? What are the components worth? How many hours did he have to spend designing this? How long does it take to build one unit? In all those cases, the answer is hardly "50% of a monotribe." The procedure was already described in detail. And you don't get a hole drilled in the unit for the price, for obvious reasons. The only remotely hard thing to accomplish must have been to find a lead for the connector.

As far as I'm concerned he's upping the price just because he can, not because he needs to. I think it's his right to do this, until someone else starts to sell the same thing cheaper. That's how business and market economy works. But that doesn't mean it's not overpriced.
bartleby
darenager wrote:
Sure the actual value of the parts is probably about $20
do the maths - it's more like 5 USD - probably less.

nitro2k01 wrote:
The only remotely hard thing to accomplish must have been to find a lead for the connector.
ebay. (at least that's what i'm hoping. i've ordered a pack of 10 - although i only need 2. i'll let you know when they have arrived and i have checked that they actually fit. if they do, i will have some spare ones to offer here).

nitro2k01 wrote:
I think it's his right to do this, until someone else starts to sell the same thing cheaper. That's how business and market economy works. But that doesn't mean it's not overpriced.
well said. (and nuff said - let's focus on further tribe hacks! external audio w/o internal osc, anyone?)
darenager
I pretty much agree that he is charging that because he can, but still seems comparable to similar products - take a look at Asol or Kenton mod kit prices, the same argument could be applied yet those need a fair bit more DIY skill.

I don't think it quite works out at 50% of the price of a monotribe does it? Here in the UK the monotribe is £160, and converting $75 to £ is about £47 so it seems more like less than a third of the price?

I think what justifies his price is he is AFAIK the only person offering a kit that anyone with a screwdriver can install. I did mine myself, as did you and plenty of other guys here, but some people don't have the knowledge, tools, time, skill or inclination to do so, and all he is doing is catering for those guys. So really what you are paying mostly for is the guys time and the guarantee that it will work.

If someone else started offering a kit at a lower price then good luck to them too.

Anyway, thank you for documenting the process in the first place thumbs up
Altitude909
darenager wrote:
I pretty much agree that he is charging that because he can, but still seems comparable to similar products - take a look at Asol or Kenton mod kit prices, the same argument could be applied yet those need a fair bit more DIY skill.

I don't think it quite works out at 50% of the price of a monotribe does it? Here in the UK the monotribe is £160, and converting $75 to £ is about £47 so it seems more like less than a third of the price?

I think what justifies his price is he is AFAIK the only person offering a kit that anyone with a screwdriver can install. I did mine myself, as did you and plenty of other guys here, but some people don't have the knowledge, tools, time, skill or inclination to do so, and all he is doing is catering for those guys. So really what you are paying mostly for is the guys time and the guarantee that it will work.

If someone else started offering a kit at a lower price then good luck to them too.

Anyway, thank you for documenting the process in the first place thumbs up


There is a HUGE difference between that $75 kit and what Kenton and Synhouse offer, both those companies developed the interface for something that was not designed for it, designed and made a custom circuit board, and sell a professional piece of kit that adds midi to a device that was NOT designed for it

The guy that sells that montribe kit just went to a website, got the instructions bought 5 parts and soldered them to a piece of protoboard. The monotribe already has a header for a connector there, you NEVER need to solder anything to get a monotribe to have midi, there already is a connector there for it. There is no magic to adding midi to the monotribe ITS ALL READY THERE, all you need to do is add a connector and an optocoupler. I wont be charging nearly that much for my midi kit and that will be done on a manufactured board
darenager
http://www.kentonuk.com/products/items/sockets/roland/tb303.shtml

5 Socket 303 kit £45.60 - 5 jack sockets, some resistors and wire.

Again, all the facilities for the functions offered by this kit exist in the 303, its simply a matter of connecting to them.

I'm not trying to be argumentative, but just point out that it is in line with similar existing products.
bartleby
just a quick update: got the midi in mod breadboarded with a 6n136 as described by nitro2k01, now it's working great!
altitude909 was right: if you want to do this mod, do it right and go for the opto method, even though it's slightly more complicated...

any news on analyzing the firmware? not an easy task i guess. wish i could help, but i don't know a thing about coding (or decoding).
darenager
Did some drum mods yesterday, well worth doing, extending the decays a bit makes it sound more expensive and lush. lol
Altitude909
Quick shots of my build:





Couple of observations about the "monomod" blog:

2k2 pot is too big (considerably). 1K log or 500K log would be better, also 300R resistors are too small imho on the snare and kick (the extreme distorts), I used 470R and that sounds much better

The individual outs need amplification BIG time, the level is nothing close to anything useful, the bleed he mentions is from the sheer fact that you have to boost the signal 10 dB to even get it close to usable. If anyone has a sexy opamp circuit that runs on 0-5V, I am all ears since that is what is needed here.
bartleby
Altitude909 wrote:
Quick shots of my build:

nice! where did you get those tiny pots + korg-like knobs? looks really cool.

thanks for warning about those resistor values and individual drum out level issues. those monomod things were next on my list - but maybe i'll wait for further improvements...
darenager
Altitude909 wrote:

The individual outs need amplification BIG time, the level is nothing close to anything useful, the bleed he mentions is from the sheer fact that you have to boost the signal 10 dB to even get it close to usable. If anyone has a sexy opamp circuit that runs on 0-5V, I am all ears since that is what is needed here.


SMD LM324? They use these in the Monotribe so should be easy enough, quad so just enough inputs for the drums allowing the snare noise and frame to have their own inputs.
Altitude909
bartleby wrote:
Altitude909 wrote:
Quick shots of my build:

nice! where did you get those tiny pots + korg-like knobs? looks really cool.

thanks for warning about those resistor values and individual drum out level issues. those monomod things were next on my list - but maybe i'll wait for further improvements...


Alpha 9mm snap ins from Mouser, the shaft has the pointer on it. The shafts are considerably shorter than the Korg ones but it works out perfect since when you epoxy them to the inside of the case they are just a hair taller than the orginal ones that are on the PCB.

As far as the monomod stuff, the decay mods he did are pretty much spot on as far as what you want to do, just the values needed to be tweaked IMHO. The output section needs work though.. will look into the LM324, just happen to have a bunch on hand.

darenager, you have a schem for that thing?

Also, the two 3.5mm above the power are midi in and out smile
sempervirent
Is there a site that consolidates the various mods in one place? The Monomodder site covers a few mods, I'm seeing a few others here, etc. I'd be willing to set up a Wiki site if anyone's interested, just because it would simplify my effort in making some of these mods. I know that this thread is an attempt at that but a linear forum thread is not the best schema for organizing information like this.
darenager
I think the pinout is the same as the dip version


Then just config it as a non inverting amp, might have to play around a bit with values to get the levels right (and enough gain) they are a little noisy but the whole monotribe is quite noisy anyway so not a huge issue.

I did not use any published drum mods for mine, I just have 4 switches with centre off (so the stock sounds) then a variation on each side of the switch, its not pretty but works great. A good way to get tonal mods is connect a wire to ground and a wire to each of the drum mod points then have a play around with some components and a piece of solderless breadboard thumbs up
bartleby
Altitude909 wrote:
As far as the monomod stuff, the decay mods he did are pretty much spot on as far as what you want to do, just the values needed to be tweaked IMHO. The output section needs work though.. will look into the LM324, just happen to have a bunch on hand.

very cool. usable individual outs for the drums would be great!
even just an individual out for all the drum voices combined - of for the synth voice would be cool.

sempervirent wrote:
I'd be willing to set up a Wiki site if anyone's interested, just because it would simplify my effort in making some of these mods.

good idea!
nitro2k01
Wonder if you need a full wiki just for the monotribe. Use the Muff wiki instead?
DBM
Anyone know what DAC chips are used for sending the lfo and env cv from the arm ?
Veqtor
If anything the wiki should cover all the korg mono's...

That could be kind of useful. I wonder if korg dislikes people posting the schematics etc
nitro2k01
Veqtor wrote:
If anything the wiki should cover all the korg mono's...

That could be kind of useful. I wonder if korg dislikes people posting the schematics etc
Don't think they would care much. If the schematic download page is any indication, all they care about is protecting their ass from a lawsuit if you accidentally the whole thing while modding your mono*.
Same thing with their Monomania contest. If you look at the how to enter page you see this: "The use of a modified monotron/monotribe is acceptable.*

* Korg does not recommend modification of its products."
nitro2k01
Anyway, FINE, I'll be setting up a wiki soon.
Altitude909
nitro2k01 wrote:
Anyway, FINE, I'll be setting up a wiki soon.


And i will contribute smile
darenager
Just built a little box with midi in and out, works great! thumbs up



If anyone in the UK wants me to make them one £40 inc postage

It has about 18cm of cable between it and the Monotribe, it just plugs into the port so no DIY skills needed, the cable just goes between the top and bottom half of the case, nice and simple. PM me if interested.
Altitude909
and the market is heating up smile
darenager
Heh, nah I won't be making many, just until the parts run out - ordered some extra as I have a few of my own to do so thought why not. Going to do mine internal though.

I'm going to try and explore some other mods like proper seperate outs for the drums and maybe VCO mute.

What are those two buttons on yours near the new pots at the top?
Altitude909
They're switches for the hats and noise decay (on-off-on)
computer controlled
Nice MIDI box =]
n.d
Check this out:
http://hackaday.com/2011/12/03/reverse-engineering-a-korg-monotribe/
nitro2k01
Welcome to muff's, n.d. This is where that happened. Check out page 12 of this thread. smile
nitro2k01
Ok, the wiki is up. I totally forgot about this, but now I've finally installed a MediaWiki installation and given it a monotribe theme. I'll add existing info if someone else doesn't do it before me. (Need sleep wink )
http://mono-wiki.dx7.se/Main_Page
Your life will be easier if you create an account instead of editing anonymously, btw.
Altitude909
well my amp board is done and laid out smile

I went with a simple TL074 instead of the LM324, it had less distortion and sounded better to my ears. The channel bleed is still there but without some serious modifications to the mainboard, this is not going to go away. If anyone has any ideas how to remedy that, I am all ears.


bartleby
excellent! another kit in the making?
bartleby
nitro2k01 wrote:
Ok, the wiki is up. I totally forgot about this, but now I've finally installed a MediaWiki installation and given it a monotribe theme. I'll add existing info if someone else doesn't do it before me. (Need sleep wink )
http://mono-wiki.dx7.se/Main_Page
Your life will be easier if you create an account instead of editing anonymously, btw.

cool! i've started a first draft of the midi mod page, but didn't get very far as
- i'm currently at work and not near my monotribe
- this is the first time ever i'm contributing to a wiki, so i have a lot to learn about formatting etc.
i hope my first feeble efforts inspire some more experienced wiki wigglers to complete what i have started. smile
Altitude909
bartleby wrote:
excellent! another kit in the making?


I may do combo boards with the midi and amp on one pcb but that will require soldering for the amp section, the midi will still be plug and play. The grounds need to isolated between the two anyway so it's no big deal
darenager
Altitude909 wrote:
The channel bleed is still there but without some serious modifications to the mainboard, this is not going to go away. If anyone has any ideas how to remedy that, I am all ears.


Might be worth taking a look at the 808 schematic, I think they used a 1k resistor after the level pot for each sound - maybe to eliminate bleed?

Edit - oops not after the level pot, but right before the mix buss.
Altitude909
Yeah, it already has resistors where it sums the signals. Problem is that this was never designed with individual outs in mind so they just passively mix the signals and and then amp it. In my MB808 (and I assume the 808 as well) all the instruments are amped individually THEN sent to the mixer so you can easily tap them for the individual outs without anything else. I'm thinking of trying a LDO diode in line with the resistor
bartleby
Altitude909 wrote:
I may do combo boards with the midi and amp on one pcb

good idea. while you're at it, how about adding trigger outputs for the three drum sequencer outputs?
Altitude909 wrote:
but that will require soldering for the amp section, the midi will still be plug and play.

no prblem, i'm not afraid of soldering, just a little lazy. smile
darenager
Hmm, looking at the drum schematics what about if you cut the trace after the mixing resistors R32, R48, R53, R68 therby isolating the sounds from eachother, then use diodes and switched jacks so that when you were not using the separate outs they would still work as normal?
nitro2k01
Altitude909
I think you messed up the pinout somehow. All the negative inputs are tied to the same point, whereas you have positive feedback through R1, R6, R9 and R10. Unless I'm missing something crucial, that conenction just makes no sense and would theoretically put the opamp into a comparator mode of operation, where it simply outputs high and low depending on whether in+ > in-.

Furthermore, if you run it off of the supplies from the serial header, you've only got 3.3V, and you'd have to be careful that your selected component can handle such a low supply voltage without problems, and you'd have to be careful to bias the signal correctly to make sure it stays within the rails, if you want to avoid distortion. As far as I can see, you're AC coupling the the input without biasing them, which is problematic.

You need to be careful about the biasing even if you're using the 5V supply, of course. I think I remember seeing a virtual ground at maybe 1.5 V in use when probing around a few months ago. (I may be wrong on this.)
darenager
Pins 2,6,9 & 13 don't appear to be connected? I looking at this on my phone so might be wrong hmmm.....

Edit - Assuming that you'd want to be using it as a non inverting amp.
nitro2k01
darenager wrote:
Pins 2,6,9 & 13 don't appear to be connected? I looking at this on my phone so might be wrong hmmm.....
They are connected to two traces that lead outside of the image.
darenager
Oh yes, I see that they go under the IC d'oh!

I would have thought they should go like this


Edit: the d'oh! was at me for not seeing the connections, not Altitude909 thumbs up
darenager
Where is the best place to pick up the 5v?
Altitude909
nitro2k01 wrote:
Altitude909
I think you messed up the pinout somehow. All the negative inputs are tied to the same point, whereas you have positive feedback through R1, R6, R9 and R10. Unless I'm missing something crucial, that conenction just makes no sense and would theoretically put the opamp into a comparator mode of operation, where it simply outputs high and low depending on whether in+ > in-.

Furthermore, if you run it off of the supplies from the serial header, you've only got 3.3V, and you'd have to be careful that your selected component can handle such a low supply voltage without problems, and you'd have to be careful to bias the signal correctly to make sure it stays within the rails, if you want to avoid distortion. As far as I can see, you're AC coupling the the input without biasing them, which is problematic.

You need to be careful about the biasing even if you're using the 5V supply, of course. I think I remember seeing a virtual ground at maybe 1.5 V in use when probing around a few months ago. (I may be wrong on this.)


There are other parts that are not shown, namely a voltage divider for the +5 rail for a virtual ground. I am running this off the analog supply, not the digital one. I have the circuit done and tested on bread board so I know this works and unless I borked something on the schematic, it works fine. Thankfully I did not dream this up myself, Oliver from Mutable did it up for me, I just laid out the board.



darenager wrote:
Where is the best place to pick up the 5v?


There is a thick trace right by the marked outputs that I tapped, just look for the big one, its pretty obvious
bartleby
Altitude909 wrote:
Oliver from Mutable did it up for me

i thought he was on a family holiday? so that's how he spends his holidays. smile
Altitude909
bartleby wrote:
Altitude909 wrote:
Oliver from Mutable did it up for me

i thought he was on a family holiday? so that's how he spends his holidays. smile


I humped his leg about it before he left smile
nitro2k01
The schematic looks sound, but the circuit board layout, as shown in the previous post, does not. It appears you have swapped + and -. On TL074 and LM324, pin 2 (and the other symmetrical pins) are used for - (the inverting input) and and pin 3 (+symmetrical) are used for + (the non-inverting input.)

In the circuit board layout, you've connected pin 1 (the output) to pin 3 (the non-inverting input) through R1. Just check it thoroughly again.
Altitude909
nitro2k01 wrote:
The schematic looks sound, but the circuit board layout, as shown in the previous post, does not. It appears you have swapped + and -. On TL074 and LM324, pin 2 (and the other symmetrical pins) are used for - (the inverting input) and and pin 3 (+symmetrical) are used for + (the non-inverting input.)

In the circuit board layout, you've connected pin 1 (the output) to pin 3 (the non-inverting input) through R1. Just check it thoroughly again.


Borked schematic it is.. eagle has the + and - inputs swapped (+ is on top, not -) compared to the schem I was sent. Will fix smile

Thanks..
darenager
How much gain is this set-up giving you? ie how much did you need to boost the drums to get a respectable level?
darenager
I'm wondering if an MC3403 might be a better choice, its a single supply quad op-amp that can run from as little as 3v, supposedly it is better for audio applications than the LM324 (and presumably the TL074 too)

Any thoughts on this?

http://www.futurlec.com/Motorola/MC3403P.shtml

EDIT: or even better? the MC34074

http://www.futurlec.com/Motorola/MC34074DG.shtml
SYN7HOR
Someone figured out a dirty way to "silence" the osc while filtering external stuff!

http://www.youtube.com/watch?feature=player_embedded&v=DXYdeTpeosw#!
bartleby
modulation, modification, what's the diff? hihi
Altitude909
darenager wrote:
How much gain is this set-up giving you? ie how much did you need to boost the drums to get a respectable level?


Its pretty much equal to the main out. On my mixer with both faders at unity the two channels are almost identical. The individual output is somewhat noisier since it is before the muting circuit but its plenty good level wise and perfectly usable.

Ill snap up some of those opamps next time i put in an order and see if it makes any difference. Honestly, the TL074 sounds fine and short of the additional env noise you hear over the individual outs, the difference from the main out is indistinguishable.
darenager
Thanks.

Yeah the main reason I thought of those is that they can be used with a single rail supply, so no biasing needed and keep it simple, I'm not super technical so I don't mind spending a small amount more to keep it within my basic abilities lol

The second op-amp (34074) I mentioned is supposed to be very good for audio, much quieter and less distortion than the LM324, so I might attempt a swap out with the 324 in the monotribe to see if the noise floor improves.

I might breadboard something up and try a few things, I'm wondering if shorting the output of the drums to ground would mute them, mute switches would be pretty handy I think.

If you get the chance to make a quick recording of your mod I'd love to hear it thumbs up
aksen
SYN7HOR wrote:
Someone figured out a dirty way to "silence" the osc while filtering external stuff!

http://www.youtube.com/watch?feature=player_embedded&v=DXYdeTpeosw#!

ah excellent, should've thought of that d'oh!
dddaviddd
Hey everyone! I love the monotron and have been using it for one year applying it to almost every song we've made so far... now i went and bought the monotribe. One of the main reasons I did it was to not be dependent on batteries (especially in live situations!).

Thing is I also bought a Gator g-bus-8 power supply some month ago and i wonder if it's possible to plug the monotribe in the gator without blowing anything up!

http://www.thomann.de/se/gator_gbus8_multi_power_supply.htm
Anyone tried this? If not: is there any way how to make it work with the gator? On the monotribe it says 9V dc, same as gator... but I have no idea what mA it needs or... in fact I have not a clue which way mA goes.. to much could damage... too less would... i don't know!!! help

ps. I'm using the european power system (if that would make any difference)
thanx alot / David
DBM
dddaviddd wrote:
Hey everyone! I love the monotron and have been using it for one year applying it to almost every song we've made so far... now i went and bought the monotribe. One of the main reasons I did it was to not be dependent on batteries (especially in live situations!).

Thing is I also bought a Gator g-bus-8 power supply some month ago and i wonder if it's possible to plug the monotribe in the gator without blowing anything up!

http://www.thomann.de/se/gator_gbus8_multi_power_supply.htm
Anyone tried this? If not: is there any way how to make it work with the gator? On the monotribe it says 9V dc, same as gator... but I have no idea what mA it needs or... in fact I have not a clue which way mA goes.. to much could damage... too less would... i don't know!!! help


ps. I'm using the european power system (if that would make any difference)
thanx alot / David

It needs 1700ma center pin + , 9v ... The plug is odd too .
The korg ka350 is the optional PSU ( same as microkorg xl )
Altitude909
DBM wrote:

It needs 1700ma center pin + , 9v ... The plug is odd too .
The korg ka350 is the optional PSU ( same as microkorg xl )

i seriously doubt it needs 700 mA supply much less a 1.7 A one. The thing runs on 4 AA batteries, its not drawing a lot current
DBM
Altitude909 wrote:
DBM wrote:

It needs 1700ma center pin + , 9v ... The plug is odd too .
The korg ka350 is the optional PSU ( same as microkorg xl )

i seriously doubt it needs 700 mA supply much less a 1.7 A one. The thing runs on 4 AA batteries, its not drawing a lot current

Well the ka 350 is in fact 9v 1.7 a .... and it runs on 6AA batteries
Altitude909
Alrighty, now that the buzz from the ferric chloride is starting to wear off, I proudly present my midi i/o board.

I have enough parts on hand for 10 kits. $40 including the two TRS to DIN5 midi cables (6ft each). The connectors in the pictures are for a mod job I am doing for a customer so the kit versions will be threaded 3.5mm jacks with the round knurled washer. All you need to do is to drill two holes and plug it in.

I'll get a formal FS thread up shortly



mckenic
thumbs up

Want!
Kyeld
Altitude909 wrote:
Alrighty, now that the buzz from the ferric chloride is starting to wear off, I proudly present my midi i/o board.

I have enough parts on hand for 10 kits. $40 including the two TRS to DIN5 midi cables (6ft each). The connectors in the pictures are for a mod job I am doing for a customer so the kit versions will be threaded 3.5mm jacks with the round knurled washer. All you need to do is to drill two holes and plug it in.

I'll get a formal FS thread up shortly

http://midiot.net/monotribe/monomidi1.jpg
http://midiot.net/monotribe/monomidi2.jpg
http://midiot.net/monotribe/monomidi3.jpg


I registered just to say how awesome that looks. I'm looking forward to hopefully buying a kit for my monotribe.
computer controlled
Want as well
bringmeup
I've been lurking for a while... I finally registered after seeing that beauty! sign me up for one as well...
bartleby
Altitude909 wrote:
I proudly present my midi i/o board.

very cool! are you still planning a combined kit for midi i/o and drums audio outputs? if so, i'll wait for that extended version. otherwise i'm definitely in for a midi i/o kit...
Altitude909
I dont think there will be a combined board due to size constraints but the amp board is done and made but still needs testing
bartleby
hm, not much happening so far at nitro's monotribe mod wiki. i've added a rudimentary article about how to add vca and vco audio outputs according to matrixsynth. haven't tried this yet, but it does look highly plausible. smile might be a cheap alternative to adding three or even four drum outputs.
Altitude909
more progress:



Sounds really good smile

Tried the MC34074 btw and there is no difference. I attribute that to the fact that the MC34074 is the same thing as a TL074 d'oh!
bartleby
it cetainly looks good. smile

where would you place this inside the tribe? just gluegun it to the plastic bottom of the case?

i still think this would fit really well onto a combined pcb with the midi i/o.

otherwise, i guess i'll be taking one of each...

(happy new year btw)
Altitude909
I stuck it here:

tringbal
hello(...sorry if my english is bad)
i m planning to do midi in modification
my seting is: midi out from computer( ableton )who go to
midi in ehx 2880 looper and from midi thru of the 2880 to the monotribe midi in
does somebody know if the simple way modification with only 820r
will work for the sync(bpm), start and stop.... thats the only 3 thinks i need from monotribe midi
thanks
bartleby
there is only one way to find out: try it! the 820r method never worked for me, but others have reported good results.

if it doesn't work for you, you can always get one of altitude's very promising kits instead.

@altitude: any plan when they will be availble?
crippletoe
Hi,
Has anyone figured out a way yet to have CV and GATE outputs?
could be the most amazing thing to use that sequecer to control my Eurorack!

...fantasies...
darenager
^ Easy way add midi out and cheap midi-cv.
bartleby
but that way you'll get the 'midi-out repeats last note played instead of rests' bug (described here and here) that i was going to do this video about. (i already have recorded the video and audio footage. now i'll have to find a way to edit and mux it. as i mentioned earlier, it will be my first video ever - so be patient).
darenager
Thats true, but once you have the cv and gate using something like a sample and hold or logic module could yield some interesting rhythmic variations where the pitch was the same but with different gating.

Proper cv and gate mods would be better though.
crippletoe
Hi,
sure proper CV and Gate would be better.
personally i find it a little pointless to go to through midi only to generate control voltages again.
i might be completely misunderstanding the structure of the instrument but isn't it being controlled by cv and gates internally anyway? why go to digital only to return eventually back to analogue?

must be an easier way.. i would expect even easier than getting midi out. no?
darenager
Yes it is using CV and gate internally but note sure if it is v/oct, so after finding the right points on the pcb some additional circuitry would possibly be needed to buffer and scale the cv and gate.

I think trigger outs for the drums would be easy enough, just pick up at the points before the inverters in the drum schematic, I'm guessing the internal drum sounds are triggered by shorting to ground (s-trig) so the inverters are being used to invert the logic pulses from the sequencer.
crippletoe
Quote:
Yes it is using CV and gate internally but note sure if it is v/oct, so after finding the right points on the pcb some additional circuitry would possibly be needed to buffer and scale the cv and gate.

or simply running that through a quantizer (which i hope to get very soon) somehow it makes sense to me that it would be v/oct.
any clue on where to look for these points? also, if gates are being generated for the synth, getting these and not the drum triggs would be even better.. hmmppff.
darenager
It is more likely to be Hz/v I think. It would probably be easy enough to find the gate by tracing back from the envelope, CV point must be somewhere between the ribbon and VCO.
Altitude909
Going through the monotron info, the internal CV and gate type signals would be pretty useless since the scaling and levels are not anything close to usefull. Monomoder did some work controling the CV but he did that by just tapping the ribbon cable connection. I'd say a midi to CV/Gate box would be easier to implement
crippletoe
well.... not entirely useless if you own an ms-20 or 10.
smile
or am i wrong?
you can even use an ms20 to convert to v/oct.
darenager
If the range is very small then it would be quite involved scaling and bringing it up to V/Oct, it might not be Hz/V that was just a guess, I have not been in and had a poke around.
Altitude909
crippletoe wrote:
well.... not entirely useless if you own an ms-20 or 10.
smile
or am i wrong?
you can even use an ms20 to convert to v/oct.


Nothing in common with those other than the Korg name and a similar conceptual design
crippletoe
and, in respect to the latest posts, the same tracking system....
darenager
darenager wrote:
it might not be Hz/V that was just a guess, I have not been in and had a poke around.


Yet...
Altitude909
crippletoe wrote:
and, in respect to the latest posts, the same tracking system....


not sure what the CV and gates are level wise for the MS series but I doubt its 3.3v like in the monotribe
crippletoe
I have used the monotribe clock out to trigger notes on the ms20 in the past, i dont remember if i ran it through the external signal processor or not (it has a gate out)
about the CV, the whole conversation here revolves around being able to play specific notes but actually, i personally often use the ribbon controler randomly to just get series of pitches in rhythm without any certain tuning or scaling system. i think the results can be interesting enough to use.
gonna try get this done smile
darenager
0-8v on the MS for CV.

Yeah for the Monotribe clock you can invert it in the setup so it is positive or negative, negative would be ok to trigger an MS10/20/50 etc.
nitro2k01
I've only poked a little for CV/gate, immediately when I got my 'tribe, but it would likely not be a very useful scale. Furthermore, since the oscillator is digitally tuned, the curve might not be entirely linear. (Why care that the signal is exatly 1 V/Oct or 0.362 V/Oct when you can just find values for each note on startup...) And this would very likely need buffering from an opamp in order not to detune the oscillator.

But what could be easy to use and useful for some modulöar applications is trigger pulses and maybe the LFO/env output. Then you can use the oscillator from the 'tribe into your modular instead. (Although that signal won't be as hot modular oscillator usually are.
Altitude909
What I do think it would be useful for is to drive a monotron
machetemirage
Has the external audio input been hacked to behave like the monotron yet?

There's this workaround so far

http://www.youtube.com/watch?v=DXYdeTpeosw

The filter sounds so nice with my guitar. With the noise and multi-waveform LFO, this would be cheaper than getting an MF-101/CP251. If only Korg hadn't made this silly design choice.... waah
Altitude909
Here is a quick video of my decay mods + the output amp

sines
Cracked open the Monotribe last night and got the "simple" MIDI working. Kinda excited about just that.

However, I'm getting stuck hi-pitched notes, is this perhaps a result of not using the opto-coupler? I don't have patience for Mouser or Digikey since I'm ordering such few items, is there a suitable replacement at Rat Shack? May have to put in an order for the right stuff instead of the usual hack methods at the studio. confused

Additionally when the machine is slaved to MIDI, the internal sequencer is not resetting on the 1-0-0-0 position. Any trick to get around that?

About to jump into individual outs and BD/SD/HH decay mods. I unfortunately have like 20+ Bourns 250ohm long shaft mini-pots that would fit perfectly, but the values seem to be too far off for anything close to this. Doubt there's an easy way [like sticking a resistor after the pot leg?] to make these work as is. Perhaps they can find a use in a sequencer or something... guessing this is why I got a bag of them for next to nothing. confused

If you've done the decay mods, without making a separate circuit board [I don't really have the space for doing that sort of thing in NYC] .. it would be great to see some detailed photos.

Lastly -- the envelopes are being controlled by the micro controller, right?... would be super nice to have dedicated knobs for all of that *ish.
Altitude909
how high? That seems odd, I can track to F7 and after that, it does not play anything.

The decay mods are not on a circuit board, I just glued the pots to the inside of the case and ran wires out to the marked mod points. Here is the wiring:


I would NOT use 2k2 pots here, 1K or lower would work better (500 or 250 ohm since you have them). Also 300R to ground may be a little too little, its gets pretty out of control at the extreme so a 470R may be a better choice, especially for the kick

The way I did the wiring on mine was to simply run wires off the pots and switches to the back of the PCB where I stuck the resistors. Note in this pic where I have resistors soldered to the ground plane

sines
cool! Did you post some details about the Op Amp? Getting a few LM324N's just in case. hmm.
Altitude909
I just used a TL074, the LM324 was giving some weirdness in the kick. The schematic is a few pages back
sines
any other vanilla op amps? I bought some 741s and 2 TL 082s just in case.... but the TL074's are "low noise".. hm.

http://www.ti.com/product/tl074?CMP=AFC-conv_SF_SEP&partnerName=DSA
Altitude909
Generally, I like TL07x for audio and TL08x for voltages. I used the quad just because there are 4 signals to boost up.
sines
I am starting to see that. the TL07x are not available at Rat Shack. I wish manhattan had like an electronics street like they do in Toronto. there is 1 guy who gets some specialty components on Canal Street; really difficult to do that kind of shopping here.
Altitude909
Radio repair shops maybe? Its a really common part. Lm324 will work but you might need to add a cap across the 100k
sines
I thought I'd be able to find another parts place here too but my searches are dead ending at every turn. Unfortunately, real estate is a premium here and you know that RS makes more money off mobile phones than they do DIY parts. razz

What cap, then, if you don't mind me asking? sorry for the retarded Qs...
sines
so this little diagram helped those who can't read a schematic so well.. [like me] grin

http://www.scripterblog.com/2011/09/korg-monotribe-mod-part-1-drums.ht ml



I tried the follow your suggestions Altitude909 about using 250ohm pot and a 470ohm resistor [and about 12 other resistors] but I couldn't get achieve the original kick drum release length in range with any pot that I had. I tried a 10k and 100k, but they were only useful towards the end of the turn, as you'd expect.. However, unlike the new 250ohm pot, I could get back to the "shortest" release of the original decay, as well as the long boom [yes, we're approaching 808 style decay].

I know this is electrical engineering 101 here, but I'd really love to use 1 pot to get through the entire range without throwing a switch in between. Is this limitation by Korg, or by the n00b DIY-modder like myself?

Thanks again!
Altitude909
sines wrote:
so this little diagram helped those who can't read a schematic so well.. [like me] grin


I tried the follow your suggestions Altitude909 about using 250ohm pot and a 470ohm resistor [and about 12 other resistors] but I couldn't get achieve the original kick drum release length in range with any pot that I had. I tried a 10k and 100k, but they were only useful towards the end of the turn, as you'd expect.. However, unlike the new 250ohm pot, I could get back to the "shortest" release of the original decay, as well as the long boom [yes, we're approaching 808 style decay].

I know this is electrical engineering 101 here, but I'd really love to use 1 pot to get through the entire range without throwing a switch in between. Is this limitation by Korg, or by the n00b DIY-modder like myself?

Thanks again!


So a 250 is too little. I didnt try the lower values. The way it works is that there is a threshold there where after a certain resistance, it is essentially back to stock. On mine its 1.33K (the 1K pot + the 330R in series).

The switch thing is really just the best possible solution to the fact that the SD noise and HH decays need high resistance to ground to make a difference and there no pots that have a 20 meg ohm range so we settle with 3 fixed values (20M, 5M, stock)

[quote="sines"..
What cap, then, if you don't mind me asking? sorry for the retarded Qs...[/quote]

small, 10P ceramic. I cant verify this works though
Veqtor
Altitude909 wrote:
Here is a quick video of my decay mods + the output amp


Cool, what were those pots you used on the front?
Altitude909
Veqtor wrote:
Altitude909 wrote:
Here is a quick video of my decay mods + the output amp


Cool, what were those pots you used on the front?


9mm snap in Alpha from Mouser..
darenager
Thinking of adding a sub oscillator to mine, using a 74HCT74 flip flop, take the top pin (square wave) of the waveform switch into the clock input of the flip flop, tie the inverted 1Q to the 1D input, and tie the 1S and 1R inputs to ground, then take the output from the inverted 1Q output into the audio input of the monotribe, probably via a mix control (pot) hmmm.....

That should work right? Could be pretty nice having a sub oscillator SlayerBadger!

Anyone tried this? The 74HCT74 should be ok as it is 5v, a similar thing (4013) is used in the SH-101
darenager
Hmm or maybe just use a 4017, take the square into the clock pin, output from Q1 and tie Q3 to reset?

Might have a go at breadboarding these up w00t
darenager
Think it should be easy to have mute switches for VCO and each drum voice by tieing them to ground via a switch, just a theory but if the drum out points on the pcb are grounded they mute, so the VCO might too - not sure if it is good electronic practice to do this though hmmm.....

Maybe this thread should move over to DIY section, probably some guys there might be able to help?
Altitude909
My midi demo is up:

darenager
Here's mine
DBM
Any idea if the CV voltage is consistant between all the mono's ?

Running LFO and ENV out to from the Monotribe to a Monotron Duo would be kinda sweet . Or even between DUO , Delay , original etc.
Altitude909
DBM wrote:
Any idea if the CV voltage is consistant between all the mono's ?

Running LFO and ENV out to from the Monotribe to a Monotron Duo would be kinda sweet . Or even between DUO , Delay , original etc.


Yeah, thinking the same thing for a while. Even have a CV buffer ready to go for when my delay finally arrives..
DBM
Altitude909 wrote:
DBM wrote:
Any idea if the CV voltage is consistant between all the mono's ?

Running LFO and ENV out to from the Monotribe to a Monotron Duo would be kinda sweet . Or even between DUO , Delay , original etc.


Yeah, thinking the same thing for a while. Even have a CV buffer ready to go for when my delay finally arrives..


Cool let me know if you get it going be fore I do ( much more likely )
saddox
Anyone tested replacing R73/R74 with a sterepot(50k or something in that area)? Should change tone of BD.

Same should work R58/R59 for the tone of the SD.

Could be done by just mounting the stereopot in parallell over the existing resistors.

Or maybe I´m completely wrong... more coffee may be needed.
Maybe the mod already exists?
nitro2k01
saddox wrote:
Anyone tested replacing R73/R74 with a sterepot(50k or something in that area)? Should change tone of BD.

Same should work R58/R59 for the tone of the SD.

Could be done by just mounting the stereopot in parallell over the existing resistors.

Or maybe I´m completely wrong... more coffee may be needed.
Maybe the mod already exists?
The tonal part of the BD and SD work by feeding a pulse into what is essentially a bandpass filter with the resonance cranked up to a setting where it nearly self oscillates. What mainly controls the pitch is the three capacitors. I changing those resistors would only tip the balance to either create a distorted oscillation that never decays or that oscillation never begins. Feel free to try it, though. You can pretty easily wire a resistor in parallel to lower the reistance. For example, putting a 15k resistor across another 15k resistor would halve the resistance. Wiring a 30k resistor across would lower the total resistance to 10k and so on.
http://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistors
darenager
I found the trig out points for the 3 drum sounds, not measured them but they light up a LED probe I made, these will be super handy for triggering modules IMHO, probably need to make up a little buffer/amp board, anyway on the pic below the highlighted sections are the trig points.

crippletoe
darenager, this is excellent news! thanks for this!
this is half way towards sequencing a modular system from a monotribe. or a polysynth arppegio.
incredible!
grin
darenager
No probs thumbs up You will probably need to add a buffer to each trig out to be safe, I tested it with my modular this morning and works fine, protection diodes would probably be a good idea to.
Altitude909
so my delay arrived today and its got the same patch points labeled as the monotron..

So the todo list:

VCO off in monotribe
Pitch CV out of MT to delay
Gate out of MT to delay
darenager
I think you can turn the VCO off simply by connecting it to ground, that is how it works with the drums anyway, so might be worth a try.

I did a proto of the trigger outputs mod, using a 4050 non inverting buffer, works great with my modular now.

Are you going to fit the delay inside the MT?
darenager
Update: Just tested the grounding the VCO and it does turn it off, noise still comes out though (bonus) I just tried it from the VCO switch but you will need to tap it before it goes into the switch to turn off all waveshapes.
Altitude909
darenager wrote:
Update: Just tested the grounding the VCO and it does turn it off, noise still comes out though (bonus) I just tried it from the VCO switch but you will need to tap it before it goes into the switch to turn off all waveshapes.


POIDH? Curious where you are hitting it. Does it process the aux in like you would expect with it grounded? I traced out from the switch yesterday with a scope but they go to the front of the board quickly and I dont feel like tearing my shit apart again.

Dont think the delay will fit anywhere but I still plan on hacking into it. Maybe breaking the VCO feed into the filter, boosting it up and running it into the aux in on the MT for a second VCO. Like the monotron, it needs some TLC
darenager
lol I just used a test probe, clipped one end to the metal bracket on the jack board, then touched the lower pin of the wave select switch and it shuts it off.

Did not test the aux in but I'm fairly certain it will still work as noise still works, really need to find a better point to tap from though as when you change the switch the other waves still sound.
saddox
Yes, and the span of "working" resistance seems to be quite small to get oscillation (calculating a little bit). Better left untouched maybe.

nitro2k01 wrote:
saddox wrote:
Anyone tested replacing R73/R74 with a sterepot(50k or something in that area)? Should change tone of BD.

Same should work R58/R59 for the tone of the SD.

Could be done by just mounting the stereopot in parallell over the existing resistors.

Or maybe I´m completely wrong... more coffee may be needed.
Maybe the mod already exists?
The tonal part of the BD and SD work by feeding a pulse into what is essentially a bandpass filter with the resonance cranked up to a setting where it nearly self oscillates. What mainly controls the pitch is the three capacitors. I changing those resistors would only tip the balance to either create a distorted oscillation that never decays or that oscillation never begins. Feel free to try it, though. You can pretty easily wire a resistor in parallel to lower the reistance. For example, putting a 15k resistor across another 15k resistor would halve the resistance. Wiring a 30k resistor across would lower the total resistance to 10k and so on.
http://en.wikipedia.org/wiki/Series_and_parallel_circuits#Resistors
vancity lites
[/quote]The switch thing is really just the best possible solution to the fact that the SD noise and HH decays need high resistance to ground to make a difference and there no pots that have a 20 meg ohm range so we settle with 3 fixed values (20M, 5M, stock)[/quote]

Hey, i've been following this thread for for a few days now and I just want to thank everyone for the info. It's been really helpful.

I thought i would add myself to the forum to show you guys my snare decay mod. I'll get a video with the audio soon. For now heres some pics though. [img]

I used a 1p12t rotary switch that feeds 12 different resistor values.

from 5.1m-66m

i decided to do everything on a small board so that i can further experiment with other resistor values and pots and stuff. i plan to do the midi circutry on the same board as well.

Trying at the moment to find some good sounds out of the BD OUT and BD DECAY. Anyone had much sucess? the best i've gotten so far is a 2k pot with a 160r in series with 240r connecting to gnd. It rolls a bit but i'd love to get more punch and and thwack... Has anyone tried anything other than resistors and or pots? I intended on finding 12 bass drum sounds on the other 12x switch.. we'll see.
darenager
Whoa! Nice job!

I'm going to add CV and Gate out next using this little tiny PCB
http://www.midi-hardware.com/index.php?section=prod_info&product=MINIC V
SlayerBadger!
zmb
darenager wrote:
Thinking of adding a sub oscillator to mine, using a 74HCT74 flip flop, take the top pin (square wave) of the waveform switch into the clock input of the flip flop, tie the inverted 1Q to the 1D input, and tie the 1S and 1R inputs to ground, then take the output from the inverted 1Q output into the audio input of the monotribe, probably via a mix control (pot) hmmm.....

That should work right? Could be pretty nice having a sub oscillator SlayerBadger!

Anyone tried this? The 74HCT74 should be ok as it is 5v, a similar thing (4013) is used in the SH-101


Hey did you go anywhere with this? I was thinking of doing something similar, either a subosc or some kind of detuning mod where I'd run a line from the wave outputs through a pitch-modifying knob (not sure where that'd come from though) and back to the audio output to sort of clone them with extra pitch control.

For the sub-osc, could you run a line from the ribbon's pitch control, drop it an octave via added resistance (if it's a volt/octave set up), and feed it into a very simple 555 square-wave generator that would route back to the audio output?

Just thinking of ideas, sorry if I sound unrealistic. I'm pretty new to this whole business so I don't know if that's just a pipe dream but I have some entry-level experience with circuit building.. I also just ordered parts to add the drum decay and MIDI mods.
darenager
Not done it yet, but here is the theory - take a tap from the square wave output, buffer it and run it into a cmos divider clock input, then take an output or 2 to get the sub divisions required, bring the level to an appropriate output then into a pot for mixing, take this to the tip connection pad of the audio in jack, voila sub osc. No need to use a 555 as the divider will handle the octave drop, if you wanted to go further you could have perhaps -1, -2 and -3 octaves all from the same chip. Something like a cd4017 or cd4040 seems ideal. The only limitation is that the sub octaves would of course be squarewaves, but a small price to pay for the sake of simplicity IMHO, the SH-101 only has square/pulse sub octaves and it is still very useable/awesome.
machetemirage
My monotribe's "triangle" looks like this



How could this happen? It's a very interesting shape.
darenager
Yeah I figured it wasn't a pure triangle as it sounds much brighter, so thanks for scopin' it, any chance of posting the square and ramp too? I think they might have non typical shapes too, at certain frequencies the square sounds quite 303ish so it might possibly have weird line on the top of the wave.
machetemirage
Sawtooth



Square

darenager
Hah! Knew it, thanks for posting thumbs up
darenager
What sort of pitch did you grab these at?
machetemirage
In the 32' Range, something of an F for the triangle and somewhere around a C for the saw/square.
nitro2k01
machetemirage wrote:
My monotribe's "triangle" looks like this



How could this happen? It's a very interesting shape.
This was one of the first things I noticed. It may be a legitimate botchup, but it could also be deliberate decision so the "triangle" would have more harmonics so the filter would behave better at higher resonances. Without it, a triangle would have the vast majority of its spectral energy around the fundamental. Since it's an odd function, a perfect triangle has no second harmonic. And since the Fourier series has a 1/(n^2) response for higher harmonics instead of 1/n, the third harmonic would already have just 1/9 of the amplitude. In other words, a triangle is a pretty dull wave.

Simply put, if you'd crank up the resonance, the filter would overdrive when tuned to the harmonic, while letting "nothing" through higher. This would make it sound pretty ugly with an envelope.

Another theory of mine is that this the monotribe is using a sawtooth core oscillator and is then using a triangle waveshaper. However, this waveshaper is a bit starved at 5V and can't handle the full amplitude range of the incoming sawtooth.



In other words, when the amplitude is above a certain point (the thin line) the wave is folded back back. However, perhaps they first double the volume and thus the waveform gets a bit distorted in the top. Or something along those lines. I think the monotribe would somehow work much better if it wan't constrained to single rail +5V.
darenager
Well whatever the reason I think it is better than a pure triangle in this particular context, I guess the price point is probably more the reason than a concious design choice, I'm still amazed at what you get for the money, and whilst it probably would sound a lot 'better' with a beefier split rail power supply, battery operation would probably have to be sacrificed. But for a cheap box I don't think it can be judged too harshly. If it was $500 maybe. thumbs up
darenager
It would be interesting to see if there is much variation between different units, and also if the wave shapes remain consistent across the whole VCO range.
zmb
darenager wrote:
Not done it yet, but here is the theory - take a tap from the square wave output, buffer it and run it into a cmos divider clock input, then take an output or 2 to get the sub divisions required, bring the level to an appropriate output then into a pot for mixing, take this to the tip connection pad of the audio in jack, voila sub osc. No need to use a 555 as the divider will handle the octave drop, if you wanted to go further you could have perhaps -1, -2 and -3 octaves all from the same chip. Something like a cd4017 or cd4040 seems ideal. The only limitation is that the sub octaves would of course be squarewaves, but a small price to pay for the sake of simplicity IMHO, the SH-101 only has square/pulse sub octaves and it is still very useable/awesome.


Ok I'll look into it, I'd be really interested to get any kind of quasi-multiple oscillation out of this guy. I jumped to a 555 since that's all I've really had experience with. Anyway I'm gonna run some tests when I get my stuff in the mail.

edit: just as an update, I've been working on the subosc thing a little bit (I'm quite busy but have found time here and there). I've been using a 74HC74 flip-flop. I've gotten .... results. One time. But it was muddy and irregular. I think one of the problems may be the slightly-irregular shape of the square wave, so the clock input may be missing low-to-highs. I guess I'll just have to keep testing.
monophonic
Hi,
I've been lurking here a bit and decided to add drums decay to my Monotribe, so thanks to all modders for all the useful technical info and pictures.
I'm going to do the same mods as Altitude909 and others already did :
- pot & resistor for BD Decay and SD Noise Decay,
- switches for SD Noise Decay and HH Decay.
But I'm wondering : would it make sense to add pots for each parameter ? Could it allow more control over parameters (SD Frame Out, SD Noise Decay and HH Decay) ? Or am I totally wrong ?
Altitude909
monophonic wrote:
Hi,
I've been lurking here a bit and decided to add drums decay to my Monotribe, so thanks to all modders for all the useful technical info and pictures.
I'm going to do the same mods as Altitude909 and others already did :
- pot & resistor for BD Decay and SD Noise Decay,
- switches for SD Noise Decay and HH Decay.
But I'm wondering : would it make sense to add pots for each parameter ? Could it allow more control over parameters (SD Frame Out, SD Noise Decay and HH Decay) ? Or am I totally wrong ?


It would make perfect sense if you could find a 20 meg pot razz
Kyeld
I found this custom decal service that does music skins. Turns out they have a monotribe skin editor to customize and make an overlay.

http://www.styleflip.com/index.php?main_page=product_info&cPath=1_16_1 8&products_id=564

I'm going to modify this Korg supplied overlay for version 2 to include the location of my MIDI jacks.

http://www.scribd.com/doc/83532114/Monotribe-Overlay-for-Print-Japanes e
zmb
zmb wrote:

edit: just as an update, I've been working on the subosc thing a little bit (I'm quite busy but have found time here and there). I've been using a 74HC74 flip-flop. I've gotten .... results. One time. But it was muddy and irregular. I think one of the problems may be the slightly-irregular shape of the square wave, so the clock input may be missing low-to-highs. I guess I'll just have to keep testing.


OK I tried again tonight and got much better results. Looks like I just had the flip-flop miswired due to my infamiliarity with it. I got an interesting sound (not as muddy this time, actually sounds pretty decent), but I'm not sure how to verify that it is indeed half the frequency. I know I have it wired correctly because I tested with LEDs and a 555 timer at about 1 Hz and it definitely halves the frequency, the way I have it wired here.

Also it is very loud in the mix without a sizable resistor in between! This makes me worried that it is just repeating the waveform with some added noise and distortion from the extra electronics (giving the distinctly different sound), but without changing the frequency. The FFT spectrum from Ableton also didn't show any obvious signs of a subosc... it didn't change much at all despite what sounded like a significant change in the tone... Any ideas?

Here's my set up (S and R tied to the power source was the only way I got a varying response in the LEDs, and the Out is to the monotribe's audio in jack):


EDIT: PS: I buffered the voltage in because I think the 74HC74 was drawing too much current or something, it kept shutting down the monotribe whenever i'd connect it.
Oldhaunt
saddox wrote:
Anyone tested replacing R73/R74 with a sterepot(50k or something in that area)? Should change tone of BD.

Same should work R58/R59 for the tone of the SD.

Could be done by just mounting the stereopot in parallell over the existing resistors.

Or maybe I´m completely wrong... more coffee may be needed.
Maybe the mod already exists?


what about using VARIABLE CAPACITOR?!?!
could you use this to tune and even picth down or up on the fly?

what cap would you replace and what would be the best range?

i have no idea about the tech behind an idea like this but just throwing it out there to see what you all think?
somthing like this

http://au.element14.com/vishay-bc-components/bfc280811229/capacitor-va riable-2-to-22pf/dp/1215709

would be good to get some tom sounds on this ting w00t
Infrablue
Does anyone know what point on the circuit board I could use to get a CV output from the LFO?

I love the range of the LFO on the Monotribe and want to send it to the CV inputs on an A6 Andromeda (and other things).

I'm thinking there may even be a spot that could output the attenuated CV so I could use the speed and amount pots on the Monotribe for the CV out signal.
Infrablue
Tonight I finished and tested a mute mod for the VCO on the Monotribe.

There is the cool way of doing this using LFO to put the VCO out of hearing range, but I wanted to use the LFO to modulate the filter for incoming sounds.

Just simply run a wire from any of the VCO wave selector points and run it to ground. I put on a switch so I can turn it off and on.

The mute only works for 1 of the 3 waves, so you could even do it without a switch and leave out your least favorite of the 3. But the switch is easy. So this makes it possible to run audio through the filter without the VCO.
It leaves the noise in the mix if you turn it up. It does need a gate, but I just run the sequence with 1 step looping and it stays gated. You can run the sequence and the gate times open and close the audio in so that's pretty cool.

All tested out and working.
jonah
Does the monotribe respond well to dying batteries? The monotron does some really interesting things and I was thinking I should figure out how to do a power sag mod.
bmot
Infrablue wrote:
Tonight I finished and tested a mute mod for the VCO on the Monotribe..... [SNIP]....Just simply run a wire from any of the VCO wave selector points and run it to ground. I put on a switch so I can turn it off and on.

applause
hey, well done Infrablue, that is a useful mod. loads of people have asked about doing this. Can you confirm where the VCO Wave Selector points are? I borrowed a picture from an earlier post, uploaded by Low_Gain, which should help. I hope he doesn't mind

darenager
darenager wrote:
I think you can turn the VCO off simply by connecting it to ground


This works for drums too if you want to do drum mutes.
machetemirage
jonah wrote:
Does the monotribe respond well to dying batteries? The monotron does some really interesting things and I was thinking I should figure out how to do a power sag mod.


Mine just stopped, showed a blinking red light, and turned off. It never died mid song or had any weird behavior.
Infrablue
bmot wrote:
Infrablue wrote:
Tonight I finished and tested a mute mod for the VCO on the Monotribe..... [SNIP]....Just simply run a wire from any of the VCO wave selector points and run it to ground. I put on a switch so I can turn it off and on.

applause
hey, well done Infrablue, that is a useful mod. loads of people have asked about doing this. Can you confirm where the VCO Wave Selector points are? I borrowed a picture from an earlier post, uploaded by Low_Gain, which should help. I hope he doesn't mind



That's the perfect image to use... it already marks where to do the mod. This image shows where the WAVE outs are... I actually ran a wire from the one marked here in red, but you could do the blue and black one instead. Red is the sine(ish) wave. Then run to ground (with an added switch on the way if wanted).

Was playing around more with it, and I love that I can do just noise sounds and even noise sequences now. The filter seems to have a built in key follower to it so the steps do alter it.
Infrablue
machetemirage wrote:
jonah wrote:
Does the monotribe respond well to dying batteries? The monotron does some really interesting things and I was thinking I should figure out how to do a power sag mod.


Mine just stopped, showed a blinking red light, and turned off. It never died mid song or had any weird behavior.


I think a power sag would be cool... now that I have the VCO mute mod working... when I first unmute the VCO while it's running... it fades in with some great saturation-ish tone... so yeah, potting that would be very cool.

Had an old analog casio that would just really make cool dying tones when low on batteries... good stuff.
machetemirage
Is there a possible "mix" mod for the snare? It would be cool to find a nice combo of frame and noise. I know I could send the two outs to a mixer, but I'm wondering if there is a point on the board that controls the blend for the factory sound....


EDIT: Or the decay mods could just increase or decrease the amount of each... d'oh!
Altitude909
machetemirage wrote:
Is there a possible "mix" mod for the snare? It would be cool to find a nice combo of frame and noise. I know I could send the two outs to a mixer, but I'm wondering if there is a point on the board that controls the blend for the factory sound....


EDIT: Or the decay mods could just increase or decrease the amount of each... d'oh!


Just wire a pot like a panner
the_beast
Altitude909 wrote:
machetemirage wrote:
Is there a possible "mix" mod for the snare? It would be cool to find a nice combo of frame and noise. I know I could send the two outs to a mixer, but I'm wondering if there is a point on the board that controls the blend for the factory sound....


EDIT: Or the decay mods could just increase or decrease the amount of each... d'oh!


Just wire a pot like a panner


That's a great idea, you could drill an extra two holes in the case as well, one for the mix out and one for th potentiometer. There is tons of room in the case, I have mangled mine with 13 holes for outs and decay mods.

This thread and this forum are both great!
Lento_Zoom
Does anyone know if anybody is getting anywhere on decoding the firmware? Do we know if it is totally out of the question to hope for custom firmware for the monotribe?
Suineder
I don't think it's totally out of the question considering my v2 Monotribe is still able to go into update mode.
nitro2k01
Yeah, it doesn't seem to be locked down. The big difficulty is to actually create custom software for the hardware.
syntezik
Hi Guys !!! i'm new here, i follow the instruction here, i made a couple of modification , but know i got a real problem. i touch a cable with GND to some place on Pcboard and now my monotribe stuck. it turn's on, all red light flash, than green light FLUX star flashing,than REC than PLAY and than GATE TIME. the red light under the nr8 start blinking and..... thats it. nothing happend. no sound, no response for touching keys. ( i think it's only the sequencer, becouse when i touch BD out or Snare Out with this cable with GND there is a sound - looong BD or SN with endless decay). please help. i was finishing all the mods, i only have to drill the holes for all pots and switches and this baaaaad luck find me in the last couple minutes :(
darenager
Hmm, try reflashing it by doing the v2 update.
syntezik
well ,thanks for fast reply smile my monotribe is back to life !!!! i remove the batteries and leave MT for about 2 hours. everythnig back to normal. sorry for my panic. i'm ok now smile MT also smile
w00t
darenager
thumbs up Cool!
X11
hi i'm new here
modding the monotribe at the moment,
just wanted to thank you all for all the winfo.


i didn't read it anywhere yet (mostlikely it somewhere)but here my my mod.
at the hihat decay part i made an on off on switch with on one side 15m to ground and at the other side a 10n cap to ground (wich makes decay longer).
then also an 22n cap(could be higher)to a momentory on button >to ground,
this is a open hihat on the fly button.
just a very nice addon i think.
the longer decay cap works also with the snare noise but i use a 25m resistor 0.0022 cap there.(changed c55 to 0.0082 better then stock for me less amplitude).
and a extra 0.0033 cap for the button.
the trigger pulse from the base kick ik parralled c69 with a 0.022 cap aswell (with switch attached) making the base kick more pounding/overdriven .
the other side of the switch connects the cap to ground wich smoothens the attack pulse but lowers bass amplitude aswell.

try to make audio clip soon but my baby just born so little time to mod:)

keep up the good stuff much love from hollland
hans
Altitude909
wow, nice first post:)

Might have to give those a whirl
X11
hi again,

just a longshot but looking at the drum schematics,
and r195 pentagrammed:) it made me curious.
i added the NotUsed 100k resistor and applyed a pulse(from hh sd bd)
it seems to make accented drum notes.
with the hh pulse the bd gets accented when hh is on same spot etc.
i tried with midi to find this pulse but no luck there yet.
the "missing resistor" has a function and maybe it is accent.
anyone has a clue?

greetings
hans
janmaat
Infrablue wrote:
bmot wrote:
Infrablue wrote:
Tonight I finished and tested a mute mod for the VCO on the Monotribe..... [SNIP]....Just simply run a wire from any of the VCO wave selector points and run it to ground. I put on a switch so I can turn it off and on.

/6124/6004321150_deb1cd4cee_b.jpg[/img]




I connected the lower one of the 3 wave outs to ground -- MT didn't boot up. Then I replaced the direct wire with a switch, and voila: it did boot up, but when disenagaging the switch, it behaved strangely: the other wave forms changed in character. I then did the same with the middle wave out, and it worked just like in the post of OP. Conculsion: MT uses combines different wave outs to create the actual waves which are not square square, saw or ^, so if you ground one of these, you can modulate the other wave forms. the ^ wave seems to be the best for said mod, but it seems to make sense to fiddle with all 3 possible mod points to find out what exactly is going on -- and always use a switch rather than just a hard wire, or it may be that v2 os dosn't boot up properly if the wave is grounded at bootup. As for triggering, you can then "save" the gate for an "empty" wave, and then it lets you use VCA and LFO for whatever you feed into Aux in, which is quite fun.
janmaat
I've managed to make a simple line out for the drums. I you open the 'tribe, you can spot where the pot for drums volume is soldered onto the PCB: two big blobs and three small ones. I soldered the left of the three small ones to tip of a jack out, and jack out shaft to ground. Result is a (mixed) drum out independent of the pot. The pot still functions as before blending the drum mix into the complete mix for the mt line out. I guess if you solder to the middle of the three legs, your drum volume would influence the drum line out, but that's theory since I'm happy with my steady drum out.
MickeyBoyeeee
Altitude909 wrote:

Alpha 9mm snap ins from Mouser, the shaft has the pointer on it. The shafts are considerably shorter than the Korg ones but it works out perfect since when you epoxy them to the inside of the case they are just a hair taller than the orginal ones that are on the PCB.


Hey there - beautiful jobby on your monotribe!
Thanks for telling us where you got the knobs.
What about those nice little switches? Model? Supplier?

Thanks
MickeyBoyeeee
X11 wrote:
hi i'm new here
modding the monotribe at the moment,
just wanted to thank you all for all the winfo.


i didn't read it anywhere yet (mostlikely it somewhere)but here my my mod.
at the hihat decay part i made an on off on switch with on one side 15m to ground and at the other side a 10n cap to ground (wich makes decay longer).
then also an 22n cap(could be higher)to a momentory on button >to ground,
this is a open hihat on the fly button.
just a very nice addon i think.
the longer decay cap works also with the snare noise but i use a 25m resistor 0.0022 cap there.(changed c55 to 0.0082 better then stock for me less amplitude).
and a extra 0.0033 cap for the button.
the trigger pulse from the base kick ik parralled c69 with a 0.022 cap aswell (with switch attached) making the base kick more pounding/overdriven .
the other side of the switch connects the cap to ground wich smoothens the attack pulse but lowers bass amplitude aswell.

try to make audio clip soon but my baby just born so little time to mod:)

keep up the good stuff much love from hollland
hans

Any chance of a demo? How long is the decay on "open HH"?
darenager
I have long decays on my MT hat, you can hear it on this clip and some of my others, I also used caps for snare and kick as well.

kvnvk
nice set of videos, really shows off what you can do with multiple units. applause
darenager
1 monotribe is fun, 2 is twice as good, etc hihi
mammut
janmaat wrote:
I've managed to make a simple line out for the drums.


For me this is better than individual outs. Too good! Is the level of the new drum output acceptably similar to the factory output? I'm only waiting to find a good deal on a used mtribe before I try your mod...
o-live
anybody know where is the Controlled voltage of the vco ?

and where i can found other "out" of from the sequencer
because i want to drive other module with us .

also i search to find the schematic of the synth part but is still not available

thank you for your help

...

SlayerBadger!
mammut
With the no-solder MIDI kits like Altitude909 's, if a MIDI keyboard is plugged in, will the monotribe still respond to sync pulses? Sorry I'm too zoned to figure out the right search terms if this has been answered.
o-live
excuse me if my english is too bad for understanding my question Mr. Green

i don't have the midi kit i ,would to control only with cv (in /out)

What i would to do is to find who create the current voltage for control the vco inside the monotribe ,and have the possibility to use this control or other control from my modular .

i want to make an input and output from this different point in 3.5" jack for drive it by other modules or to control eurorack vco in same time .
with the sequence created by the ribbon because i like so much the "flux mode" .

do you have an idea of wich "IC" do this :





also i search the other trig/gate output for control other drum modules outside with the monotribe sequencer ( i like the possibilities of euclidean sequencer inside)

thank you for you knowledge
Altitude909
You would need a lot more circuitry to boost the level to something useful. The MT runs internally on 5v and the VCO CV wont be scaled to anything useful other than itself.

Drum triggers are no problem though, search this thread. You need either an internal or external level shifter for them since they are only 3.3v
o-live
i understand this is not easy for control other thing swith the sequencer inside .

but do you now wich IC create the current voltage ?


do you have an idea of the type of circuitry AOp for make a correct voltage
to use with the standard eurorack voltage format ?



yes for the trigger i have see on this post someting interesting before
,i need to search the source of begin of this (trig)

good day
Altitude909
It probably is generated by the micro controller and buffered. There are no schematics for this part is, it wont be easy to figure out. What will be a show stopper is the fact that it wont be scaled to hz/volt or volt/oct and it will most likely be over a very small range (3.3V max) so even if you could find it, buffer it, and level shift it up to Eurorack levels the pitch would be completely off. If you want to control something else from the sequencer, you're better off using a midi to CV converter

For the trigger mods, look at darenager's posts several pages back
mOBiTh
arrrrggghhh to the midi input mod!

just spent all night trying to get it to respond to midi but it just doesnt.

I tried with a 6N136 and direct via a series resistor and even checking the input signal on a scope revealed nothing wrong.

Any ideas?

I was trying to clock it off my octatrack.

hmmmn frustrating night help
awoke
Given the growing Eurorack scene, I'm surprised Korg doesn't make Eurorack modules. They made a Nintendo DS MS-20 synth app after all!
Altitude909
mOBiTh wrote:
arrrrggghhh to the midi input mod!

just spent all night trying to get it to respond to midi but it just doesnt.

I tried with a 6N136 and direct via a series resistor and even checking the input signal on a scope revealed nothing wrong.

Any ideas?

I was trying to clock it off my octatrack.

hmmmn frustrating night help


Use a better opto, I use a 6n137 with a 10K pull up
wednesday
I am working on building up my soldering/electronics skills mostly just because but also so I can eventually attempt to add midi functionality to the monotribe. in the meantime, would something like this http://www.analoguehaven.com/expertsleepers/adaptorcables/ connected from say an sp404 into the sync in work? just to get the two units syncd?
Kingnimrod
I just installed the midi tribe I/O - Phantom48.com is now carrying it so the shipping is about half as much as getting it from Brazil.

For the trouble it saves you, this kit is totally worth it. Makes the Monotribe more usable. I like running the onboard sequencer and "interrupting" with keyed notes from the Minibrute.

I think I will probably drill out the case to mount the midi jacks in the side - I don't like them hanging out of the battery case.

Right now I am playing it with my Minibrute as a controller, as a second oscillator. If only the brute's arpeggiator sent midi...
wednesday
kingnimrod do you happen to have a link? i can't find it on their site.
Kingnimrod
You have to email them directly. They haven't put it on their site yet. Amazing machines told me about them.
tIB
does anyone sell a circuit to boost/drive the individual outs?
Altitude909
i may a couple boards left, shoot me a pm with your email and ill get back to you
darenager
My internal MIDI mod, more mods soon!

The external one is still available for those with drill fear...

thumbs up
MickeyBoyeeee
Do you have any kits available to do the midi mod? Did you use an opto-coupler?
Thanks, Mick
darenager
Yes and yes thumbs up I do internal or external the external is a 5 minute job, the internal is about a 20 minute job as you have to drill some holes.

Here is a pic of the external


Price for either is £45 plus shipping at cost, neither require any soldering, totally plug and play, they are built using decent parts by me, registered post to Canada/US is £9 Europe £8 I have stock of both kinds ready to ship.

Lots of wigglers have bought from me.

I'm also going to be doing drum trigger out boards and drum mod boards and some other monotribe mod boards too which will be compatible with these. Just waiting on parts at the moment, but should be ready in a few weeks.

PM me if interested thumbs up
wednesday
Nice darenager, wish I had waited for those. The smaller holes in the other kit are nice but kind of inconvenient when I want to connect it to my computer via midi/usb cable.
Kingnimrod
Hello Music has the monotribe on sale for $139 right now. Another $20 off if you haven't ordered before.
mckenic
Wow! That is CHEAP!

You guys see that USB interface that was on Matrix a few days ago?
darenager
Drum mods, easy fit although you would need to be able to solder 5 points and drill some holes. Working on some other really cool mods stay tuned.

Note - there are some shitty audio artifacts going on in this clip, I'll post some better sounding demo to my SC later. The kick is pretty tasty IMHO.
Altitude909
Nice spot! I like your idea of 3 different setting vs a pot. The response is so non-linear that a pot is almost pointless, better to just pick 3 good places..
darenager
Still working on this one, but showing promise I think:
mckenic
we're not worthy Wow! Keep it up!

Woah!
oscillateur
Do you have more details about the added controls ?
I'd probably be interested by a kit for that and the individual trigger outs...
Xmit
great work Daren! SlayerBadger! - would almost have made me buy a Monotribe for these mods alone if I hadn't spent up on a Micromac-D & an AnalogFour... Mr. Green
darenager
Cheers!

oscillateur wrote:
Do you have more details about the added controls ?
I'd probably be interested by a kit for that and the individual trigger outs...


There are 2 pots and 2 switches, pot 1 sets the frequency, switch 1 sets the range of pot 1, pot 2 sets the mix level, switch 2 sets the mode with type 1 up, type 2 down and centre off, meaning the modulation is off.

Yes, I will be doing drum trigger boards too, as well as mute boards, and possibly some other output boards, VCO, noise, drum mix, LFO out, (these will make it even more useful in a modular context) They are all quite easy to do but it is a matter of fitting them all inside the case.

Right now I'm trying to source some decent quality and small parts, the PCBs are not custom, but built onto very high quality through hole plated matrix boards, rather than the usual stripboard (poor quality) or home etched PCBs (would be too labour intensive and costly) or pro fabricated PCBs (not going to be selling enough to warrant the outlay)

Pricing will be from £20-30 for the simpler boards to around £40-60 for the more time consuming ones, any less than that and it is simply not worth my time.
kvnvk
cool mods you have going, and unless Korg actually makes a tricked out Monotribe XL including an extra oscillator and LFO and at the very least a simple octave button keyboard I'll definitely be planning to order some of your boards when you have them available. thumbs up
darenager
Some more info and a Soundcloud demo here

Edit - Not liking the new soundcloud UI, bah seems to take ages to process now too.
L13
awesome!
Altitude909
Finally found a place to do these for the right price, so my MT midi boards are back!
Samaepstein
Just ordered 2 from altitude! Can't wait. I've been addicted to these little buggers. . Soundcloud.com/peekaboostreetsweeper certainly use some mt I every track. Love the look of those kits from darenager as well. Great forum!
Deaf Wasp
Hey just wondering: has anyone gotten a CV out from the monotribe yet? I see a lot of talk about it but no actual breakthroughs from google. I thought it would be a good way to get a 16-step sequencer to my modular.

Crazy good work going on in here! nanners
Samaepstein
Just wanted to give a quick shout out to altitude909 for his services! I ordered two of his outstanding midi kits for the monotribe and in addition to making a great product at a great price, he also has great customer service. Due to my noob ism, I shredded a serial cable in the mt while installing my jacks and he sent me a new one in a flash! Now that's a gentleman and a scholar. Now I have my 2 mt's all midi'd up and making amazing noise!

Thanks altitude909 and misw!
sines
darenager wrote:
Some more info and a Soundcloud demo here

Edit - Not liking the new soundcloud UI, bah seems to take ages to process now too.


hey Daren,

Any word on mods like your YouTube demo? I'd love to have some of those features in the mix on mine... super sick!

Altitude909 -- your midi I/O board works like a freaking charm!
sines
perhaps I spoke too soon..

was poking around for the individual synth output, I tapped a 1/4" live output to the Saw/ Square/ Triangle output and now I've got nothing. No LEDs, I left the batteries out and everything disconnected overnight, tried again.. nada.

Any bright ideas on how to bring it back to life?
The MIDI and Bass drum mods were so much fun!


+odd
Infrablue
sines wrote:
perhaps I spoke too soon..

was poking around for the individual synth output, I tapped a 1/4" live output to the Saw/ Square/ Triangle output and now I've got nothing. No LEDs, I left the batteries out and everything disconnected overnight, tried again.. nada.

Any bright ideas on how to bring it back to life?


It was tying the middle point of the waveform select switch to ground (through a toggle switch) that got my VCO Mute mod to work... seems like when I was poking around to do that, I did hit something at some point that temporarily shut off the device, but then was fine.

Anything still shorting things together in there? Even blows on it for any debris, but hard to think what it's doing if you didn't leave anything connected in there.

Who knows... could be coincidence. Just last night I got out my Gakken SX150 and thought it was totally dead but the batteries just corroded the leads and a few rotations of one battery got it going fine. So maybe wiggle some batteries in the Monotribe.

edit... oh I see you took the batteries out... still maybe look for corrosion on where they connect.
sines
Infrablue wrote:

It was tying the middle point of the waveform select switch to ground (through a toggle switch) that got my VCO Mute mod to work... seems like when I was poking around to do that, I did hit something at some point that temporarily shut off the device, but then was fine.

Anything still shorting things together in there? Even blows on it for any debris, but hard to think what it's doing if you didn't leave anything connected in there.

Who knows... could be coincidence. Just last night I got out my Gakken SX150 and thought it was totally dead but the batteries just corroded the leads and a few rotations of one battery got it going fine. So maybe wiggle some batteries in the Monotribe.

edit... oh I see you took the batteries out... still maybe look for corrosion on where they connect.


Thx for the tips.. I am going to lightly brush the surface with a wire cleaning brush. The batteries are out, and there's zero corrosion, and I didn't touch the soldering iron tip to any wires.. but something is up.

Where did you guys find the monotribe for $119? eek!
Altitude909
fresh batteries? I've beat on mine more than a red headed step child and I still have yet to do any permanent damage
sines
Altitude909 wrote:
fresh batteries? I've beat on mine more than a red headed step child and I still have yet to do any permanent damage


Batteries were fresh and worked up until I crossed the Wave Output section. :(
so bummed because the bass drum mod was kickin' Dead Banana
Altitude909
on the base board (the one with a speaker) there is a 0603 surface mount fuse marked FU1 (it as an M on it), check if that is blown
Samaepstein
not sure if this has already been addressed, but i have put in the 4 individual drum outputs which are unaffected by the "rhythm" volume knob on the tribe. this means that by turning down the rhythm slider, the main output becomes the synth only output. didnt know if this would help anyone a it has been great for me!
wednesday
What is the easiest/cheapest way to convert a 12v gate signal from another synth to the 5v required by the monotribe's sync in? Or do I even need to worry about this?
oscillateur
I'm not sure that the Monotribe needs that (there are probably voltage regulators inside but you should wait for an answer from somebody who knows these things better than me) but to drop the voltage you'll just need an attenuator, i.e. a simple resistor.

There are probably resources online that'll tell you what value would be needed to go from 12V to 5V, and then you could easily solder the resistor in a dedicated cable or something like that.

Edit : you'll probably need to know the current in the Monotribe's circuit to know which resistor value you need. My electronics knowledge is crap, I blame too much circuit bending and programming for that smile.
Sperrle
How??? How come no one have made a cable yet?

CV control Analog 4 to Monotribe
http://www.youtube.com/watch?v=-4hT228uR-Q
darenager
^ Get the OS update first

http://www.korg.co.jp/Support/Download/Update/monotribe/

This adds CV in.
darenager
You need 4 pole mini jack, tip as GATE, ring2 as CV, sleeve Ground. It has V/Oct or Hz

I can't read Japanese but it looks like you can config it to work with most things.

Edit looks like ring1 is not used hmmm.....
BugBrand
Wow, didn't hear of the 2.11 update yet.
Nice.
Need to go back through this thread.. out of touch is me!
Sperrle
Quote:
You need 4 pole mini jack, tip as GATE, ring2 as CV, sleeve Ground.

thanks for info darenager, what kind of the jack is on the other end??? the same?

very strange that there is no info on such epic update?!? all I found is the japanese version...
darenager
I think the King Korg cable will have 4 pole 3.5mm but given the pinout it is quite easy to make a converter cable/box to use it with whatever you want. I might start making some not sure yet as might not be worth it.

For example to make a cable for the A4 you want a 4p 3.5mm to a TRS 6.35mm, total cost for cable and parts about £3 time to make 20 minutes.
radiokoala
I soldered such a cable but it doesn't work waah

One side is a 4-pole 3.5mm, and the double cable is split to two separate ones with mono 3.5mm outs (one for cv, another-for gate). When I plug any of those mono e.g. to headphones out, then speaker turns off (as it would usually do, when any cable is plugged). The same with sync in - I plug them, and monotribe stops playing (as it does when a cable is inserted but transmits no signal).

But if I plug a 4-pole jack to any of those outputs/inputs, nothing happens.

To see if cable at all is working I even plugged it with this 4-pole side to headphones out, but inserted not fully, so that a sleeve was not in a socket. Either of mono outs plugged to a mixer transmitted audio okay.

And yes, I have a 2.11 firmware.

What could be a problem??
darenager
Sounds like you don't have CV enabled in the set up?
igormpc


we need a translation here...
will i have troubles with my installed miditribe? hmmm.....
darenager
You can load the pdf into google translate and get the gist of it, I have family staying at the moment so not able to test if the midi still works, should be ok though, but if you don't want to chance it and don't mind waiting a few days I will test it - unless someone else confirms first.
radiokoala
Hey igormpc, is your name Igor?? Because if so, well so is mine This is fun!

Can't not help the namesake, and thank you very much darenager, I figured out everything thanks to your reply thumbs up

So, a translation:

to make everything work, turn off monotribe and then turn on holding SN+Gate buttons.

Step 1 = activate CV/gate
Step 2 = V/oct or Hz/V mode
Step 3 = normal gate or inverted trigger

So, basically you upload your firmware, then enter this mode and, most importantly, press step 1. CV/gate is now active, and to save changes, press REC.

Then ... that's it, there you go !! screaming goo yo

PS: Holy shit I spent nearly two hours already sequencing monotribe from my module...I will upload something soon! (Like audio. thumbs up )
darenager
Altitude909 wrote:
on the base board (the one with a speaker) there is a 0603 surface mount fuse marked FU1 (it as an M on it), check if that is blown


Yes if it is blown you can simply bypass it with a jumper - you will lose the protection of the (or not as it is blown!) fuse but if you are not able to replace it at least it will get it working again, assuming this is your problem.
wednesday
...so if this thing can accept gate triggers I'm assuming the answer to my question is yes, I can use a 12v trigger to sync the monotribe and it won't be damaged?
radiokoala
wednesday wrote:
...so if this thing can accept gate triggers I'm assuming the answer to my question is yes, I can use a 12v trigger to sync the monotribe and it won't be damaged?

"In addition, the gate voltage, please fit up to 20V."

thumbs up

BTW, as promised, I updated the CV/gate demo! (Find here)
Altitude909
"SYNC IN jack ø3.5mm monaural mini-phone jack
Maximum input level 20V" page 17 of the manua

Edit

Beat me to it :(*
Suineder
Hooooooly crap! Missing a whole new operating system is what I get for living under a rock. I'm also curious to know if it'll play nice with my MIDI mod. If so, screaming goo yo screaming goo yo screaming goo yo !

Obviously Korg really want to show off the KingKORG's CV capabilities, but this update will also allow the MS-20 mini to control the Monotribe (fuckin' stoked for that). I don't think it's a coincidence at all.
JayEm
For those with proper cables, press record and you can save your sequence. Still only 16 steps though razz
radiokoala
JayEm wrote:
For those with proper cables, press record and you can save your sequence. Still only 16 steps though razz

Woah w00t Freakin awesome.

I also discovered that in cv/gate mode sync in/out are not tied together, and you have absolutely independent clock out. Drum and synth sections therefore can have two completely separate tempos which again is quite cool!
Altitude909
Suineder wrote:
Hooooooly crap! Missing a whole new operating system is what I get for living under a rock. I'm also curious to know if it'll play nice with my MIDI mod. If so, screaming goo yo screaming goo yo screaming goo yo !

Obviously Korg really want to show off the KingKORG's CV capabilities, but this update will also allow the MS-20 mini to control the Monotribe (fuckin' stoked for that). I don't think it's a coincidence at all.


Yes. The only quirk is that when they added 8 more steps, they added them in between the 8th notes, while keeping the time signature the same so if you slave it to a midi clock, it will run at 2x normal time if you want like a normal 16 step sequence
radiokoala
Altitude909 wrote:
Suineder wrote:
Hooooooly crap! Missing a whole new operating system is what I get for living under a rock. I'm also curious to know if it'll play nice with my MIDI mod. If so, screaming goo yo screaming goo yo screaming goo yo !

Obviously Korg really want to show off the KingKORG's CV capabilities, but this update will also allow the MS-20 mini to control the Monotribe (fuckin' stoked for that). I don't think it's a coincidence at all.


Yes. The only quirk is that when they added 8 more steps, they added them in between the 8th notes, while keeping the time signature the same so if you slave it to a midi clock, it will run at 2x normal time if you want like a normal 16 step sequence

Monotribe has a half tempo setting - hold gate and then press 8. That would solve the problem. 8_)
Suineder
I know the half-tempo feature affects the sync i/o, but does it really apply to MIDI clock as well? That'd be kind of neat (I added MIDI to my 'tribe, but I truthfully haven't used it much).

Now, what would be really cool is if the engineers found a way to apply active step to all 16 steps in a sequence instead of the 8 sets of two. Not sure how they'd pull it off, though, because you already need three fingers to change the length of a synth or drum sequence. Perhaps add the gate time button? Sounds a bit unwieldy. Whatever, I'm fine with the active step the way it is.
Altitude909
radiokoala wrote:

Monotribe has a half tempo setting - hold gate and then press 8. That would solve the problem. 8_)


That does not apply to midi clock sync
telegasm
Sorry for the dumb question, but would this cable work?

http://www.lunashops.com/goods.php?id=2053
Suineder
telegasm wrote:
Sorry for the dumb question, but would this cable work?

http://www.lunashops.com/goods.php?id=2053

Maybe. It depends on how the cable is wired. If, say, the stereo tip connects to the 4-pole tip and the mono tip goes to the second ring or vice versa, it would work. You'd have to do a continuity test.
bartleby
i think it's remarkable that they can add (analog) cv/gate control via a (digital) firmware update.

does this mean that the incoming cv/gate signals are first digitized before they control the analog synth section?
and would that in turn mean that incoming cv/gate-notes will be sent as midi notes in realtime if you have the midi out mod installed?
that would make the tribe into a cv/gate-to-midi converter!

has anybody with a midi-modded monotribe and fw 2.11 tried this?
StepLogik
bartleby wrote:
i think it's remarkable that they can add (analog) cv/gate control via a (digital) firmware update.

does this mean that the incoming cv/gate signals are first digitized before they control the analog synth section?


That would be my guess. I suspect they just tied the three poles of the input jack to the GPIO pins on the CPU. So, they can do whatever the software dictates.
DJFonzi
StepLogik wrote:
...they can do whatever the software dictates.

Like maybe add CV/gate out?
That really seems like a logical step to me. I mean, the MS20 doesn't have a sequencer, right?
darenager
Happy to report that midi is still working on the 2.11 update, I have not checked thoroughly but it seems that exsisting midi functions have not had anything added or removed.
Altitude909
shame. It's good that they are still updating. The CV/Gate mod is kind of brilliant
StepLogik
DJFonzi wrote:
StepLogik wrote:
...they can do whatever the software dictates.

Like maybe add CV/gate out?
That really seems like a logical step to me. I mean, the MS20 doesn't have a sequencer, right?


Theoretically, yes. Assuming my initial theory is correct and the pins on the CPU can act as outputs and the method of connection doesn't prevent input signals (ie, one way buffering).
Suineder
I've ordered a very similar cable to the one telegasm linked to. In case it doesn't work, where can I find good quality TS and TRRS jacks to wire up into a tiny converter box?
bartleby
darenager wrote:
Happy to report that midi is still working on the 2.11 update, I have not checked thoroughly but it seems that exsisting midi functions have not had anything added or removed.

have you tried the new cv/gate input? does the monotribe translate incoming cv/gate notes into outgoing midi notes?
that would be awesome!
imagine beibg able to control all kinds of midi synths from your modular sequencers, random voltages etc!
oscillateur
Probably stupid question : what did you use to drill holes in the Monotribe case ? It's metal, right ? I've mostly modified toys and drum machines/keyboards in plastic housings so far so I'd rather not completely make a mess of everything when I'll mod mine smile.

Also, what areas are best in your opinion to put a couple of knobs and switches ? Same question knowing that I'd like to add Darenager's trigger outs board at some point in the future ?

And lastly : when I opened my Monotribe the other day to try the "official" drum mods points I couldn't manage to get a long bass drum decay. I'm basically supposed to use a pot (of adequate value) between the labeled point and ground, right ?

Thanks in advance smile.
darenager
Re the drum mods - yes, or you can just use resistors and switches as I do, then you have a on/off/on switch, middle(off) is stock, up is longer, down is booom hihi I sell drum mod boards, but out of stock at present - might be worth picking one up when you get the trig board if you want to. I will eventually get around to posting schematics, but in all honesty it is fairly low down a long list of to-do's. But it is pretty easy to figure out.

For drilling I use titanium bits, they go through the alloy cleanly and do not burr the holes, for larger holes such as for the midi sockets I use a step drill, always do small pilot holes first, then go up in size in small increments until you get the hole size you want. Measure carefully and use a centre punch and you should be fine.

Regarding the midi and CV testing, I'll be doing some more testing today so I'll post later with an update.

The 4 pole connectors are a little tricky to solder, you need a very fine bit as they do not have solder tags but very narrow stepped rod, separated by plastic insulator, the smallest connection is thinner than 1mm so the surface area for a good connection is tiny, even less than the wire you will be soldering to it. But if you take a bit of care doing it you can get a decent strong joint, a 'helping hands' type holder comes in handy.
Xmit
^

a little workround I used for soldering really tricky, tiny little buggers like 4 pole minijacks is to adapt an existing cable - you can get things like a preformed 1m 4 pole jack -> socket cable for about £1.85 from CPC & the like. Snip off the end you dont want, strip the cable cores out, test for continuity to find out what's what & then just re-wire to whatever connectors you need. If it's a split / break out cable you need use some nice heat shrink tubing.
darenager
^ Good tip - these 3.5mm TRRS jacks are a PITA.
darenager
Oh wow - it does indeed do CV to midi conversion, this is great news, it sends an initial note and pitchbend messages, so for example you can send in an LFO and everytime it recoeves a gate the LFO value will be sent as an initital note at the time of the gate and then varying pitchbend values until the gate goes low, a very good implementation, and on my initial tests looks to be very fast.
w00t
BugBrand
WOW!
Nice that I just got a 2nd one from tIB!
bartleby
that's fantastic news!

if i'm not mistaken, that would make the monotribe (w/midi out mod) the only commercially availabe cv/ gate-to-midi converter.

i think for some this feature alone might be worth getting a 'tribe! grin
darenager
Well, there is the Oplab, but it does other things too, on the other hand the way the Monotribe handles CV- Midi conversion is actually a little more elegant, the Oplab only reads a new CV value for each new gate and returns a midi note to the nearest value, the Monotribe sends an initial nearest note then pitchbend for subesquent CV values until a new gate. I suppose both methods have advantages and disadvantages.

Currently I am trying to determine if some small CV glitches I am getting are the fault of settings, the device I'm using or the Monotribe CV implementation, I'll post back later with my results. I wish Korg UK/USA would get their site updated with English update and instructions....

But either way, the Monotribe is even more incredible value now.
bartleby
oh and as i just learned from dieter doepfer, there is also a new doepfer module that does cv/gate-to-midi!

still, it's great that the 'tribe can do it, too, even if it's not quite as unique a feature as i thought.
Altitude909
oscillateur wrote:
Probably stupid question : what did you use to drill holes in the Monotribe case ? It's metal, right ? I've mostly modified toys and drum machines/keyboards in plastic housings so far so I'd rather not completely make a mess of everything when I'll mod mine smile.

Also, what areas are best in your opinion to put a couple of knobs and switches ? Same question knowing that I'd like to add Darenager's trigger outs board at some point in the future ?

And lastly : when I opened my Monotribe the other day to try the "official" drum mods points I couldn't manage to get a long bass drum decay. I'm basically supposed to use a pot (of adequate value) between the labeled point and ground, right ?

Thanks in advance smile.


Read back up the thread for how to do the drum mods, there are examples and diagrams. You can use a pot and a resistor for the mods but be forewarned that the response is not very linear so there is very little adjustment you can do with a pot (all the business is over a small range). Now i've tried a half dozen values and tapers but its a persistent problem. Picking 3 values and using a switch is as useful and easier to do

For drilling the case, a normal high speed steel drill bit will work fine. I put all my drum controls on the front next to the rhythm knob (lots of room there) so I used carbide tooling and did it on a mill. It's cast aluminum and machines easily.

Like Daren said, for bigger holes, use a step or "Irwin" drill

radiokoala
bartleby wrote:
oh and as i just learned from dieter doepfer, there is also a new doepfer module that does cv/gate-to-midi!

still, it's great that the 'tribe can do it, too, even if it's not quite as unique a feature as i thought.

Keith McMillen Qunexus also does, and I'll buy it for that. It even converts CV to MIDI CC, and with Ableton Live 9 coming out next week (which records automation finally), it's not going to disappoint. Modulating plug-in parameters with a modular? why not! hyper
Altitude909
Cable FTW

https://www.sparkfun.com/products/11580
Suineder
darenager wrote:
the Monotribe sends an initial nearest note then pitchbend for subesquent CV values until a new gate.

It's great news that the Monotribe does CV-to-MIDI, but I'm actually not surprised by the implementation. I heard the same behavior when I sent MIDI out from the 'tribe to my Microzwerg. Pressing on the ribbon controller would send the appropriate note and any movement after that just alters the pitch bend.
Altitude909
i have parts for 10 breakout boxes on order, if anyone is interested, shoot me a pm. these will with 3.5mm jacks
darenager
I made a video showing how to get proper v/oct scaling, also going to be selling breakout boxes, the one in the video is just a quick proto I made but works great.
phono1337
added jacks to mine for the cv/gate

http://www.dinsync.info/2013/03/monotribe-cvgate-jacks.html
Altitude909
Damn, Korg stock is climbing in my book.. Do they have a team of ppl sitting around figuring out dope hacks for this thing or what?
Revok
Is anyone getting drums from the gate? I can't tell if my cable is just janky as all hell (which it is) or if that doesn't work.

If I wiggle it around, I can hear a hihat coming through. Is the empty line for triggering drums?
Revok
Ah nevermind, I think its just the noise of the tribe with a gate firing and no cv coming through Dead Banana
bartleby
Altitude909 wrote:
Do they have a team of ppl sitting around figuring out dope hacks for this thing or what?

[crystal ball] as has already been speculated, the next logical step will be to add cv/gate outputs. and as with the cv/gate inputs, they will allow you to switch between v/oct and hz/v, and between v-trig and s-trig.

this will make the monotribe into a v/oct+v-trig to hz/v+s-trig converter for your ms-20 mini. the monotribe will translate between your v/oct modular gear and your hz/v ms-20 mini. it will be the new ms-02. [/crystal ball]

btw, i don't want to spoil anyone's business model here, but i don't think you'll need a 'breakout box' to add cv/gate to your 'tribe. i'm pretty sure a regular 3,5mm trrs to 3x cinch av adapter cable plus a bunch of cinch to 3,5mm trs adapters will work just fine.
Revok
I've been using the monotribe as an extra VCO all night and it's been great. Is there any way to bypass the VCA?
Suineder
bartleby wrote:
it will be the new ms-02.

Fingers crossed!
darenager
Revok wrote:
I've been using the monotribe as an extra VCO all night and it's been great. Is there any way to bypass the VCA?


Without modding, kind of if you put the EG switch in the middle position, then send a constant gate, you don't want the one shot LFO modding the VCF though or the sound might fade out depending on filter settings.
BugBrand
Nice work Daren!
darenager
Ta, hooked it up to the mighty Bug - the SEQ1 allows for super slidy fun!

darenager
Oh Tom forgot to ask if you have tried the Monotribe into wavefolder, very nice!
kvnvk
very cool Daren. SlayerBadger!
Samaepstein
Good god I love these little boxes.
JayEm
so i found i have this TRRS to RCA video cable thing that used to work with some crappy old portable DVD player.
Any idea how I'd hook this up to my minibrute?

Right now I'm hooking it up in different configurations with no luck.
If I use a standard TRS cable from the minibrutes gate out to the sync in I can gate the monotribe, but obviously lack any CV control, so it stays at a constant pitch.

I have RCA to 1/4" mono adapters that are then going into 1/4" to 1/8" to connect the TRRS cable, but so far it hasn't worked.

Help?
StepLogik
You are going to have to do some continuity tests to determine which RCA pins connect to which rings. Take out the guesswork.
JayEm
so i couldn't find my multimeter, but instead just used my punk console and a battery to figure things out.

White is the tip, red is sleeve, yellow is the first ring. second presumably is nothing?

still, no matter how i hook this up, i have no cv control. i can get gate, but nothing else.
Altitude909
JayEm wrote:
so i couldn't find my multimeter, but instead just used my punk console and a battery to figure things out.

White is the tip, red is sleeve, yellow is the first ring. second presumably is nothing?

still, no matter how i hook this up, i have no cv control. i can get gate, but nothing else.


Have you verified that the 2.11 firmware is installed?
darenager
JayEm - the second ring carries the CV on the monotribe socket, so if your lead had no connection on the second ring, it won't work. The tip carries the gate so this seems to be consistent with the results you are getting.
JayEm
Damn.

As awesome as korg is for giving out these updates, its pretty irritating they didn't use standard jacks :p

i had an old set of headphones with a TRRS jack on the end. I stripped it out and am attempting to solder together my own wire.

*sigh*
jonah
EDIT: sorry, went back 3 pages. Yay, works with a4!

Now if they just added CV outs on the 'trons... But! I wonder if they can accomplish that now, with a software update, using the same jack trick? Doesn't the monotron have have a non-standard jack implementation? Why stereo jacks for mono signals? Could Korg have been thinking that far in advance? woah

How about, delay it clock/ gate, OG is variable CV for filter sweeps and DUO is quantized CV for notes. hyper

And I wonder if they'll make a special cable for use with the miniMS20 or come out with their own breakout box.

If Korg is listening, this update turned the Monotribe into something I want to buy.
Suineder
jonah wrote:
And I wonder if they'll make a special cable for use with the miniMS20 or come out with their own breakout box.

Why would they do, or need to do, that? All of the outputs except for MIDI and headphones are already on TS minijacks. The MS-20 also emits the currently played keyboard voltage.
JayEm
Suineder wrote:
jonah wrote:
And I wonder if they'll make a special cable for use with the miniMS20 or come out with their own breakout box.

Why would they do, or need to do, that? All of the outputs except for MIDI and headphones are already on TS minijacks. The MS-20 also emits the currently played keyboard voltage.


because the monotribe does not work with basic TS minijacks.

Trust me.
Suineder
JayEm wrote:
because the monotribe does not work with basic TS minijacks.

Trust me.

Whoops, brainfart. I wasn't thinking about connecting the mini specifically to the Monotribe.
JayEm
So here's a video of my semi-functional CV cable.

I really suck at this, and at this point may just give up and wait for something to become commercially available.

I also tried DinSyncs direct mod, and undid it quickly afterwords.

Thankfully no monotribes were harmed in the process.

Just a pair of headphones and a male to male TRS mini cable.

phono1337
JayEm wrote:
I also tried DinSyncs direct mod, and undid it quickly afterwords.


nothing wrong with them seriously, i just don't get it
JayEm
phono1337 wrote:
JayEm wrote:
I also tried DinSyncs direct mod, and undid it quickly afterwords.


nothing wrong with them seriously, i just don't get it


not suggesting there is, but considering how shaky I am with making a cable, I'm sure you can understand I have little faith in my abilities not to short out something and wreck my monotribe. :p
darenager
Ok, I will be selling breakout boxes for £15 plus post - to be honest it probably only makes sense for UK guys to get from me, as postage overseas is getting ridiculous expensive (about £9 for tracked) Here is a picture, but note that the box will be a little smaller than the prototype one shown, but in all other respects it will be the same, high quality 3.5mm connectors, approx 60cm lead, if you want to buy one PM me, I won't be making many as they take a while and once you add in the cost of the parts not really making much at all on these.

the cake
hi there, straight out of the lurk zone!

so this:

Altitude909 wrote:

Yes. The only quirk is that when they added 8 more steps, they added them in between the 8th notes, while keeping the time signature the same so if you slave it to a midi clock, it will run at 2x normal time if you want like a normal 16 step sequence


isn't remedied by OS 2.11?
because that would be the main reason for me to install midi. Can someone please check?
darenager
No it still behaves the same, you can use something like a midipal as a clock divider though, to be honest driving it from midi rather than syncing the internal sequencer is a lot more flexible. If you just want to clock it you can use a narrow pulse sound into the sync jack.
the cake
thanks for clarifying!

i'm clocking the MT from gijs' master clock generator right now, but midi clock would have been convenient for start/stop/continue.

now i have to press play on the monotribe in sync, so that stuff isn't off beat. Maybe i can figure something out on the MCG's arduino...
darenager
Here is the proper version of my CV breakout box, came out really nice if I do say so myself.

darenager
With 303 sequencing
JayEm
I'm guessing the video being 3:03 long isn't a coincidence? Guinness ftw!
Altitude909
Haha Darren, we must think alike. Same 3.5mm jacks and everything razz


For ppl in the US/CA: Same Deal as Darenager

$25 USD, $6 US shipping, $12 CA. USPS just jacked international rates by 70% so US and Canada only

darenager
Ha! Yeah those sockets are very nice, Tom Bugs put me onto them a while back and I use them quite a lot now, the ones with the slotted ring do my head in, the tool for tightening them is IMPOSSIBLE to find here, I even spoke to the UK distributor, and they did not know where to get it seriously, i just don't get it
Besides, these ones look a lot neater and have a much better contact with a range of different plugs I've found.
Altitude909
just tap the holes, makes installing them a snap and they can't rotate. it's a m8x0.75 thread and i use a 9/32" pilot in plastic
darenager
Oh no I meant the type in this pic, the ones we used are fine.
darenager
These are the ones I used, think yours are this type too right?
Altitude909
gotcha, missed that part
bartleby
hm. so i installed fw 2.11 and set up and calibrated the cv/gate inputs for v/oct and v-trig. they do work, but cv control seems a little odd. when controlled by external cv, the tribe behaves as if there was some kind of portamento/slew involved. i also find this in the midi output stream: it has all these pitchbend messages where there shouldn't be any.

i've tried several different voltages sources - including my trusty kenton pro solo ii, which works very well with anything else i use it with.

are you guys experiencing the same behavior? any idea what i could do about it?
radiokoala
bartleby
try switching to the KEY mode if set to NARROW. (or otherwise)
bartleby
radiokoala wrote:
bartleby
try switching to the KEY mode if set to NARROW. (or otherwise)

i tried - but that switch doesn't seem to have any effect on how my tribe reacts to incoming cv/gate.

so, you're not seeing this behavior on yours? like a very fast portamento whenever you play a different note - and pb on the midi output when you're really just playing straight notes?
darenager
I think the PB is always sending, could be due to non exact CV values, I'll do some tests later, the flaky CV could be a slightly dodgy connection in the 4pole jack, I noticed the first one I used the width of the insulating rings was slightly off compared to the one I'm using now, and the CV seemed to fluctuate a bit, rather like slight fast vibrato.

I'll look into it and post back tonight, it would be handy if a few of us did it to get some kind of baseline indication, I will test a few of my monotribes to see if there is any variation.
darenager
Also make sure that the range switch is set to 16 when performing the calibration, I tested the pitch accuracy of mine using TC electronic polytune and got like 6 or 7 octaves of spot on accuracy. Follow the calibration exactly as in this video.

bartleby
darenager wrote:
I think the PB is always sending, could be due to non exact CV values. (...) the CV seemed to fluctuate a bit, rather like slight fast vibrato.

nope, i don't have that on mine. once the attack phase is over, mine is completely stable - both the tribe's pitch and the midi output. i get a portamento/glide-like sound a short burst of pitchbend messages only immediately after pressing a new key. obiously, the effect is more pronounced, the greater the interval between two consecutive notes. but after that, pitch and midi are stable.

re calibration: i did it as described in your video - except i don't quite understand what the bit about pressing "c4" and "c5" is about. what you're calibrating is the tribe's response to voltages, not to midi notes. what voltage corresponds to what note depends on how you set up your midi-to-cv/gate interface.

i used the first octave that i set up to be converted into cv on my kenton - i.e. the voltage range between 0v and 1v - for calibration. it tracks very reliably over all the octaves there are on my kb. so voltage calibration doesn't seem to be the problem.

maybe it does have to do with the trrs adapter i'm using...
darenager
Yeah the C4 and C5 is just lifted directly from the pdf, and probably relates to the King Korg, I used around the middle range, the main thing is to press the note before pressing play else it seems to get confused. It might also be worth trying recalibrating say between 2v and 3v to see if it makes a difference.

By PB always sending I meant on each note, rather than continuosly. I will hook up a midi monitor later and check as I have not looked since changing my cable, maybe it will be the same maybe (hoping) not.
darenager
Just tested mine, it seems that on every NEW note sent PB is sent for a few lines then if the same note is pressed no PB, but change to a different note and PB is sent again, this is regardless of a CV input note or a local keypress on the ribbon (in key mode).

Edit, so yeah pretty much the same as yours lol
bartleby
darenager wrote:
Edit, so yeah pretty much the same as yours lol

yup, pretty much exactly the same. grin

so i guess it's not a malfunction of my particular unit, or my mdidi-to-cv/gate converter, or the adapter cable i'm using. it's just how this thing works.
darenager
Yes seems so, as I said earlier I did get some weirdness on the note sounded like a wavering with the first cable I tried, since changing it the pitch is stable.
Altitude909
all this work and no one has figured what the deal is with R195 and the star..
darenager
^ Try soldering on a flux capacitor and take the tempo to 88 bpm eek!
darenager
On the schematic r195 is marked 100k NU (not used?) near a label that says PORT hmmm.....
Altitude909
Fuck it, I'm going to stuff a 100K in there and see what happens
darenager
It turns it into an 808 and 303 lol

Ha, funny since your post I have mine open probing about, damn you Sir and your inquisitive mind hihi
igormpc
do you know if i can send cv and gate and record it on internal sequencer?

i have an autobot and was thinking in sending cv/gate from it and record on internal sequencer, trying something like an extended ASR... hmmm.....

i didn't upgrade to 2.1 yet...
igormpc
and if i send cv and gate on sync in jack how can i send sequencer sync also?

i could send it using midi in jack from my miditribe, but if i wanted to use an analog clock, like my envelator's square out? hmmm.....

too many possibilities, trying to figure out a good way to sync all these boxes/sequencers...

(autobot/miditribe/kentonprosolo/nordmodular)
darenager
Yes indeed you can record external CV to the sequencer of the MT, you may be able to clock the autobot from the MT sync out or midi, the cool thing about doing it this way (synced) is that flux on will allow slides to be heard.
hamildad
Theoretical question here for people with Modulars and the new monotribe firmware. I cant test this myself as I am waiting for the TTA power boards to start my eurorack.

1) Can I put a clock/(LFO square) through a multiple and send to modular sequencer AND monotribe gate in, so they both have the same clock.

2) then take pitch CV from OUT-B from intellijel µscale and send it to monotribe-cv in to generate a pitch related to the OUT-A from µscale.

3) then bring it back in to modular via a mixer unit.

4) then to my audio outs for an in-sync, dual timbre patch with related chromatic pitches.

Is this madness? or am I onto something?

thanks for your expertise.
igormpc
hamildad wrote:

1) Can I put a clock/(LFO square) through a multiple and send to modular sequencer AND monotribe gate in, so they both have the same clock.

2) then take pitch CV from OUT-B from intellijel µscale and send it to monotribe-cv in to generate a pitch related to the OUT-A from µscale.

3) then bring it back in to modular via a mixer unit.

4) then to my audio outs for an in-sync, dual timbre patch with related chromatic pitches.


i dont have the 2.1 upgrade but i can assure you that:
1) works for me, on 2.0v on sync in.
2) i send pitch via midi to monotribe with miditribe kit and to kenton pro solo mkII > antioscillator and it works ok.
3) works for me, phones out to mh01 mixer in.
4) works for me, monotribe and antioscillator madness.
darenager
Yes you can do that with the limitation that the monotribe is either in cv/gate mode OR clock in mode, so in the scenario you mentioned the clock source would be gating the monotribe on every clock - ie no syncopation straight 16ths or whatever the clock is doing.
darenager
One other thing, the monotribe cv input impedance might differ from your modules, this can result in the cv droop if multing.
hamildad
Good news!

sounds like a clock divider might be a future purchase to split the Mtb gate in to a divisible of the modular gate.

still amazed at all the options available for the Monotribe.
darenager
Yes, and with mods things can get even more interesting. Not to mention of course it is a very decent sounding synth, honestly in 20 odd years of messing around with sounds/synth overall this humble little box has to be one of my all time favourites, no one is more surprised by this fact than me.

The drum trigger mods are really great, the roll function and individual track lengths coupled with the realtime 'playability' make it a fun percussion controller, and personally I prefer to have this kind of thing outside of the modular as it is more hands on, given that a mt costs less than all but the least expensive modules it is kind of a no-brainer IMHO.
mikro_fone
Hey Altitude909, I'm trying to PM you about that breakout box, but I'm new here and am being blocked. Can you PM me?

Thanks!
wednesday
Will the monotribe accept midi clock in cv/gate mode?
Altitude909
wednesday wrote:
Will the monotribe accept midi clock in cv/gate mode?


yup
mmtakeda55
Hi, let me introduce my new product to all of this thread.
I made a Breakout Box for Monotribe. This small box let you put CV+GATE to monotribe.
For more information, visit here, please.

http://beatnic.jp/products/breakout-box-for-monotribe/

There is language flag upper right side of this page. Use it to read in Englsh, please.
thank you all!
Altitude909
^
Nice smile Welcome Motohiko

Now we have most if not all the heavy weight Mono-modders in this thread
poladark
Well, I made my own little ugly cv/gate breakout box from parts available from the local Swedish electronics chain Kjell & Company today. Total cost was 95 SEK (price of solder, tools and band-aids excluded). (Part numbers 37671, 89014, 37150, 37195 if any Swedish people are interested.)





It's a lot of fun! Let's hope Korg decides to hook up CV control of the filter and/or VCA to the last remaining connector wire in a future firmware update.

Did the envelope clicking thing with the monotribe ever get resolved? The CV input thing has reminded me of that.
Altitude909
poladark wrote:
..
Did the envelope clicking thing with the monotribe ever get resolved? The CV input thing has reminded me of that.


yeah, noticed that driving mine from an x0xb0x. Kind of odd that it seems worse being driven from the CV/Gate vs Midi (at least it did to me)
mckenic
Did you guys see the Squidfanny vid Matrix posted?

http://m.matrixsynth.com/2013/03/squidfanny-circuit-bent-monotribe-wit h.html



VCO mute, de-click and Drums thru the filter!!!

@Poldark - that pic is giving me a terrible erection - please tell me those two together sound as sweet as I imagine?
poladark
mckenic wrote:
please tell me those two together sound as sweet as I imagine?

The TT-303 pattern generator gives the monotribe new life.
zmb
I was looking at the monotron duo and it made me wonder if there might be a way to hook up my monotribe's ribbon controller to that of the monotron duo, and thereby have an analog 3-oscillator synth. the thing is, i have the MIDI-in modification on my monotribe, so i'm not sure if the ribbon controller is still active at all or if it's being bypassed. if i'm controlling the monotribe by midi, and I somehow have the ribbon/pitch CV from the monotribe driving the monotron, would that work? Any ideas appreciated, thanks.
darenager
No it won't work, the ribbon is only used to enter notes into the MT sequencer, so even if you hooked them together - if it worked at all, it would only sound when you played the ribbon.
senecio
Hi everyone,

I am trying to find out 2 things:

1. is there any way to get the ribbon controller/sequencer of the Monotribe to send CV out to other devices? I really like the interface of the monotribe/ribbon controller and would like to sequence other analog synths and my modular with it. (Even if it means using a monotribe midi kit and midi to cv converter, if that is a possible solution)

2. there seems to be 2 popular midi kits available. (amazing machines Miditribe & Michigan Synth Works) Can anyone explain the strengths and weaknesses of the different kits in layman's terms?

Thanks for any help!!!!!
Altitude909
My kit (MiSW) requires drilling 2 holes and I offer mine with either 3.5mm TRS connectors for midi which only require 0.25"/6mm holes that can be easily drilled with a hand drill or full size DIN connectors which require 16mm holes (a special step drill is recommended for this). IMHO, this is the best way to make a rugged connection. The amazing machines kit has din connectors hanging out of the battery compartment (which means you cant really use batteries) so no drilling required. Beyond that, its the same thing. I charge $50, they charge $90
senecio
Thanks for the info! Very helpful!

Your kit sounds like the way to go for me, especially because I ALWAYS use batteries... that's half the fun of the Monotribe, having it so portable!

Did you mean that your Din kit is more rugged a connection than your 3.5mm kit... or that either of your kits are more rugged a connection than the other brand?

Also, with the Midi kit installed, will I be able to play other midi synth modules using the Monotribes ribbon/sequencer as the controller? That is what I'm mainly interested in, (not interested in sequencing Monotribe with other sequencers or playing it with a midi keyboard... I am interested in the Monotribe being in charge.)

Sorry for all the questions!
wednesday
zmb wrote:
I was looking at the monotron duo and it made me wonder if there might be a way to hook up my monotribe's ribbon controller to that of the monotron duo, and thereby have an analog 3-oscillator synth. the thing is, i have the MIDI-in modification on my monotribe, so i'm not sure if the ribbon controller is still active at all or if it's being bypassed. if i'm controlling the monotribe by midi, and I somehow have the ribbon/pitch CV from the monotribe driving the monotron, would that work? Any ideas appreciated, thanks.


I know that there is a midi mod for the monotron, so I'm thinking that the same kind of circuitry would work for the monotron duo. Then you'd need to add midi-out to the monotribe and send it to the monotron.
Altitude909
senecio wrote:
..
Did you mean that your Din kit is more rugged a connection than your 3.5mm kit... or that either of your kits are more rugged a connection than the other brand?


Both equally rugged, both have the connectors attached to the case so the worst that will happen if you tug on a cable is that it will simply disconnect. There is not a ton of real estate for full size midi connectors so the DIN kit is a bit trickier to install, if you're not comfortable drilling big holes like that, I dont recommend it.

Quote:
Also, with the Midi kit installed, will I be able to play other midi synth modules using the Monotribes ribbon/sequencer as the controller? That is what I'm mainly interested in, (not interested in sequencing Monotribe with other sequencers or playing it with a midi keyboard... I am interested in the Monotribe being in charge.)

Sorry for all the questions!


yes! you can also sequence external drums on channel 10 (the drums have GM assignments)
senecio
Fantastic! Man, cant wait. I'll be heading off to ebay later tonight to get your kit.

Thanks again for answering my questions!!!
zmb
darenager wrote:
No it won't work, the ribbon is only used to enter notes into the MT sequencer, so even if you hooked them together - if it worked at all, it would only sound when you played the ribbon.


Ah man, I thought that might be the case.
wednesday wrote:
I know that there is a midi mod for the monotron, so I'm thinking that the same kind of circuitry would work for the monotron duo. Then you'd need to add midi-out to the monotribe and send it to the monotron.

Yeah, that would be possible, seems like a lot of work for this though. There seem to be a lot of pitch CV and gate mods for both monotrons and the monotribe so maybe that route would be simpler, no microcontrollers or anything...
Altitude909
here's another monotron midi kit: http://www.marc-nostromo.com/?p=185
vstace
Altitude909 wrote:
here's another monotron midi kit: http://www.marc-nostromo.com/?p=185


This has me thinking about filter CV on the MT now hmmm.....

In other news... do you guys have anymore thoughts on adding a 1/4" synth out? (can I just tap the VCA pot?) I don't think individual drum outs will help with my live setup but the synth out would.

Altitude: Do I recall you mentioning a ganged drum out? That would work too. I'm really just after independent 1/4" synth and 1/4" mixed drum outs. Is something like this possible with your drum board?

Thanks!

Kev
Altitude909
the individual outs are the easiest way of isolating the synth (just turn down the rhythm pot). I suppose you could tap the synth voice before it goes into the final amp but that would still require an amp stage to get the level up and if you are going to do that, might as well do it to the drums since that is ten times more useful. If you want an independent mixed drum out, you can always passively mix the channels with resistors but again, 3 independent drum channels are way more flexible
LeFreq
Hey guys, great thread here! I've skimmed thru it a few times, but haven't even come close to taking it all in... Before I found this thread I did the MIDI mod and I just completed the Snare Decay Mod... I plan to do the other drum mods as well. But, for my decay mods, I've added a button to allow me to turn it off and back on. I did this because I couldn't find the 2.2K log pots and I heard (read) that you could not as easily get back to the original sound unless it was 2.2K pot and a 300 Ohm resistor. I also thought it would be cool to have it as a kill switch, to go back n forth between a long and short snare.

Well, it works! But, the button is really scratchy. I get that standard scratching sound when pushing it... any tips on getting rid of something like that? I used a Radioshack SPST illuminated push button switch I had lying around. I went Snare Decay -> Load Pin and Other Pin (no idea what that's called) -> 2k Log Pot -> 300Ohm Resistor -> Ground.

2nd question, how would I go about tapping some power from the Monotribe to power this bad boy button up? I've never done anything like that before, but I plan to do it on my TR-505 mods as well, so learning a bit about snatching power off a PCB like this would be helpful!

Ah, one last question... how are you guys wiring all of your pots to ground in these mods? Are you using separate wires to different ground points or is there some trick here? The Monobot page shows just one wire going to ground, but he has a bunch of pots/switches, so I figure they're all being grounded through this one wire?


Sorry if I'm disrupting this thread at all, I figured this was the best play to ask. Thanks in advance! we're not worthy thumbs up
sines
so.. I did some poking around near what I thought was the synth section trying to find some hidden treasures... with a 100k pot while the unit was on, and now the Monotribe won't turn on.

Where should I look first [guessing a blown SMD mount fuse?]

Beuller?
wednesday
this is not a mod, but a demonstration of a cool way to use Flux mode. i made the video



hope its helpful smile
Altitude909
sines wrote:
so.. I did some poking around near what I thought was the synth section trying to find some hidden treasures... with a 100k pot while the unit was on, and now the Monotribe won't turn on.

Where should I look first [guessing a blown SMD mount fuse?]

Beuller?


Is this a new issue or the same one from a couple pages back?
Samaepstein
wednesday wrote:
this is not a mod, but a demonstration of a cool way to use Flux mode. i made the video



hope its helpful smile


Awesome video
sines
Altitude909 wrote:
sines wrote:
so.. I did some poking around near what I thought was the synth section trying to find some hidden treasures... with a 100k pot while the unit was on, and now the Monotribe won't turn on.

Where should I look first [guessing a blown SMD mount fuse?]

Beuller?


Is this a new issue or the same one from a couple pages back?


Same issue. Forgot to go back a few pages... Oops. ;(
Will report tomorrow.
Altitude909
sines wrote:
Altitude909 wrote:
sines wrote:
so.. I did some poking around near what I thought was the synth section trying to find some hidden treasures... with a 100k pot while the unit was on, and now the Monotribe won't turn on.

Where should I look first [guessing a blown SMD mount fuse?]

Beuller?


Is this a new issue or the same one from a couple pages back?


Same issue. Forgot to go back a few pages... Oops. ;(
Will report tomorrow.


Start with that fuse. I've done all sorts of poking around in mine resulting in resets and so forth and have yet to do any real damage
sines
Yep, that's it. I just soldered a snipped resistor wire across it, all good now! Why this took me so long, is beyond me. razz
thx!
critical
Fitted seperate drum outs to my Monotribe (Thanks Altitude909!). The kick channel has a bit of crosstalk & is a little noisy.. other than that it sounds great.


Altitude909
^
Nice spot. That's where I mounted mine as well. The cross talk thing is off the board, I saw the same thing when patching out without the amp board
boxxgrooved
vstace wrote:


In other news... do you guys have anymore thoughts on adding a 1/4" synth out? (can I just tap the VCA pot?) I don't think individual drum outs will help with my live setup but the synth out would.


I'm not sure how you make a seperate synth output but if you make a seperate drum section out you will have isolated the synth on the main output.

To quote janmaat's useful post:

"I've managed to make a simple line out for the drums. I you open the 'tribe, you can spot where the pot for drums volume is soldered onto the PCB: two big blobs and three small ones. I soldered the left of the three small ones to tip of a jack out, and jack out shaft to ground. Result is a (mixed) drum out independent of the pot. The pot still functions as before blending the drum mix into the complete mix for the mt line out. I guess if you solder to the middle of the three legs, your drum volume would influence the drum line out, but that's theory since I'm happy with my steady drum out."

His theory is right. I have succesfully made a seperate drum section out seperating it from the main mix. I forget which pin did this but you can easily find out by experimenting with all of them without causiing any harm.
nitro2k01
I just got a Bus Pirate and hooked it up to the unpopulated CN13 which has suspiciously JTAG-like signal names printed next to it. Aaaaand nothing. And more nothing. And more nothing to the point that I was starting to wonder wtf I was doing wrong. Then I realized that whole header is disconnected from anything else on the board. Doh! Even the ground isn't connected anywhere. Or is it just me? :p
I'm figuring that either they removed the connection last minute because they needed the space for routing other stuff, or they deliberately left the header in to troll modders. I wonder...
computer controlled
Didn't someone on here make a cable to use from the A4 to the MT?
nitro2k01
Pretty sure I've hooked everything up correctly now, still nothing. Korg may have decided to disable the debug interface which would not surprising. This might also be an issue with the 180 ohm resistors I put in series with the signal before closing up the unit, for safety. Bla bla bla.

Next up I may have a look at using the so called single boot mode to see if I can do anything fun.
CJ Miller
Sorry if this has already been covered, as jumping into this 30+ page thread is a bit of a task...

Do any of you know of any firmware mods? Are there any firmware dumps or updates I can look at?

I have done many mods to drum machines and synths over the years, and I do often ponder the Monotribe. The only difficult thing is figuring out how to replace the record/playback modes with something suitable for me. The sounds are easy enough.
nitro2k01
CJ Miller: Yes. There's a system upgrade available on Korg's homepage. [1] It consists of an audio file with data encoded as longer and shorter pulses to represent the 0's and 1's, which you feed into the sync in jack. Me and a couple of other people have worked on decoding this data, which was successful. You should be able to get a binary file out of the sound data using the scripts available there.

Now, as for reading data, I was stomped, but I realize now that I've missed a couple of very obvious things, and upon fixing those things, I now have a disassembly up in IDA. At the start of the file there's a table of what looks like pointers, and indeed they are pointers. I assumed that the first pointer must be the entry point, which it isn't, but instead the stack pointer. So I tried to somehow shoehorn that pointer into being the entry point by making assumptions about adding or removing 00 bytes at the beginning of the file, or maybe different endinaness. Of course, the relevant information is in the data sheet. [3] (D'oh!) Furthermore, I somehow didn't realize that the processor, even though it is an ARM CPU, only supports the THUMB instruction set, which you need to tell IDA to give you a correct disassembly. (Double d'oh!) This also explains why the addresses in the table appear to be unaligned (ie odd numbers) like 0000010D for the entry point. The lowest bit tells the CPU to run in thumb mode, so the actual entry point is 0000010C.
Sometimes I'm pondering if I should not do things like this at all because I do (relatively) simple mistakes like that, when I should know better.

In IDA, open the update file from the script as a binary/raw file, choose ARM. In the options you can probably keep all options as is except automatic ARM/thumb switching which probably isn't useful. In the memory areas dialog, enter the following, as per the datasheet.

Code:
RAM start   0x2000000000000000
RAM size   0x0000000000002000

ROM start   0x0000000000000000
ROM size   0x0000000000020000


When the file has loaded, press alt+G and set the T flag to 1. This tells IDA to disassemble the code as thumb instructions. Navigate to Address 0000010C and press C to begin disassembling.

I now have a disassembly going with this as the first three instructions.
Code:
ROM:0000010C                 LDR     R3, =0x40000140
ROM:0000010E                 MOVS    R0, #0x40 ; '@'
ROM:00000110                 STRB    R0, [R3]



[1] http://korg.com/monotribe
[2] http://blog.gg8.se/wordpress/2011/12/04/korg-monotribe-firmware-20-ana lysis/
[3] http://www.toshiba.com/taec/components2/Datasheet_Sync/201011/DST_TMPM 332FWUG-TDE_EN_21741.pdf

So no, no mods or alternative firmwares available yet.
Random note: I pesonally haven't upgraded my 'tribe to even OS 2.0 yet, for two reasons:
1) I'm hoping to maybe one day dump the 1.0 firmware image just for posterity.
2) There was a note somewhere on Korg's homepage indicating in ambiguous terms that you may not be able to upgrade again after upgrading to 2.0, which scared the shit out of me. Even if it that's false (which it turns out it was, given that we now have OS 2.1) the might have upped the security somehow in 2.x, or something else that might make it more difficult to upgrade to a custom firmware image.
I think I'm just being paranoid of course, but that sometimes a beneficial trait when dealing with software that may have security features.
vstace
Thought I'd share the recent work of Squidfanny
I'm waiting on some switched pots, and will be trying these as well
vstace
Hey Altitude909, What do you think are the chances your drum boards will work in the Volca beats? Prolly too soon to tell I know, I was just curious.
Altitude909
might have to change some values but sure, my board is a simple 4 channel amp
otoskope
Just thought I should post an image of my modded Monotribe - the MIDI connectors were added a few days ago, while the (banana) individual outputs and 3 sequencer trigger outs were added last year:




The MIDI connectors are from a slaughtered old PC joystick to MIDI cable, and are connected the easy way directly to the serial port. It works fine, and what I really wanted to do was to be able to sync my Timefactors from analog clock out on my modular or D-1000 drum machine, converted to MIDI clock in the Monotribe. And it works!

The drum audio separate outs are a bit low level, and I will one day substitute the buffers I added for simple opamp gain stages. Also the triggers are a bit low level for my Bugbrand modular. Although they work perfectly for triggering, they are noticeably weak when used for pinging filters. There's a 9V supply that goes to the Monotripe internal speaker amp, and I'm thinking about using that to power the gain stage to be able to crank it up a bit.

/Palle
mammut
Not exactly a Monotribe mod question but kind of... I am syncing monotribe to gameboy, and the output of the gameboy is too quiet to sync without using gain or preamp of some kind. So I want to build one.
I have this mini guitar amp toy which is basically an input, volume/tone knobs and a little speaker. My question to Wigglers is can I remove the speaker and solder an 8th in mono cable in its place in order to interface with Monotribe? Any educated guesses?
medowl
i had these two gameport/midi adapters laying around :


based on a 6n136


based on a 6n138

they have a 15 pin serial connector, both work perfectly fine without modification.

wiring :
korg MT --> 15 pin connector

2 rx --> pin 15
3 tx --> pin 12
4 3.3v --> pin 1
5 gnd --> pin 4
otoskope
^ Good find. Maybe I shouldn't have slaugthered mine (same as your upper one)... I just used those midi leads from it, and added some resistors and stuff (following online instructions). It worked, too. But I don't have an optocoupler...

Saved some space, though.

/Palle
Altitude909
There is a pretty wide field of "what work's" and "what's right" when it comes to this. Midi is a simple serial current loop, how you get there is really pretty arbitrary as long as it works. Optocouplers and resistors are only there to maximize compatiblity
Pase
@mammut-you can easily sync the monotribe to a gameboy without any problems. Use a cable like this:

Then you have to pan all to the right a noise pulse (try different kind of noises, volume,decay to find what work fine) and connect the right to the sync in of the mono. All the rest sounds of the gb must be panned to the left, and you should connect to a mono input of amp or mixer or whatever you choose. yeah you'll lost the stereophonic sound of your chiptunes but it's ok. I use nanoloop and it works great 8_)
igormpc
i have an old nokia phone/video cable here:



I am using a rca to 1/8 adapter on white(gate) and yellow(cv) connectors and it's working ok with my autobot sequencer! smile
noikea
Similarly I found a HD camcorder cable kicking around the house. Bought a couple of mono RCA to mono audio adaptors and have been using it to control my 'tribe with my Minibrute. Works perfectly.

EDIT: Green is Gate and red is Pitch. Sorry.

mammut
Pase wrote:
@mammut-you can easily sync the monotribe to a gameboy without any problems.


Ill be damned, I just read somewhere outut was too quiet and never thought to try an unamplified signal (Ive been syncing mtribe w lsdj for months thru a gain pedal) - it does work although its harder to get the volume right. I still want to hack this amp actually as a preamp for the mtribe audio in.
medowl
finally got around to make a long noise decay for the snare drum

had the switched 5MΩ & 20MΩ mod in place but wanted somthing to make the decay longer instead of shorter.

came up with this :



the switch with 20MΩ is still in place, but replaced the 5MΩ side with a little circuit using a capacitator and some voltage input to create a controllable (by pots R3 & R4) long noise delay. the sd trigger point controls the transistor.

its an on-off-on switch. middle is the untouched snare, down is a short decay & up is the long decay.


note : i just build it with things i had laying around and sounded good, not sure about the correctness of all the resistors/capacitator etc..
works with 3.3v too and probably less. but the 3.3v point i found was feeding the onboard opamp, it occasionally shut down the opamp when i turned up the decay..
Lyncaster
i just toggled around in there, and now, it will turn on fine, but wont output sound, at all.
Kanutaros
I've just read the whole thread and there's some really great research going on. Thank you all for the great information.

I'll soon be trying a few mods on my monotribe too, once everything arrives:
- a sub oscillator by routing the Square wave out to a binary counter and a high pass filter (might DIY-up a simple fixed filter or nick the monotron's VCF)

- Midi In, maybe Midi out although I'm not sure how useful the latter would be

- Drum decay mods, apart from the snare frame and bass drum

- Might try experimenting with the drum trigger outputs, maybe use it to trigger noise oscillator with a transistor

I've seen people route the individual wave outputs to separate jacks, but is it possible somewhere to mix it in with the monotribe's VCA, kind of like the Minibrute with the mixing of the various waveforms.
Altitude909
Kanutaros wrote:
.. maybe Midi out although I'm not sure how useful the latter would be

..


Pattern backup, extremely useful
Kanutaros
Altitude909 wrote:
Kanutaros wrote:
.. maybe Midi out although I'm not sure how useful the latter would be

..


Pattern backup, extremely useful

Sorry what is pattern backup? I feel as if I'm missing out on something here...
Tifaret
Kanutaros wrote:
Altitude909 wrote:
Kanutaros wrote:
.. maybe Midi out although I'm not sure how useful the latter would be

..


Pattern backup, extremely useful

Sorry what is pattern backup? I feel as if I'm missing out on something here...


Being able to use the Midi out to record the MIDI to your computer or whatever so you can revisit the pattern later if you want.
Kanutaros
Tifaret wrote:
Kanutaros wrote:
Altitude909 wrote:
Kanutaros wrote:
.. maybe Midi out although I'm not sure how useful the latter would be

..


Pattern backup, extremely useful

Sorry what is pattern backup? I feel as if I'm missing out on something here...


Being able to use the Midi out to record the MIDI to your computer or whatever so you can revisit the pattern later if you want.

I see, although I intended on creating the patterns using the computer and play it out to the monotribe whilst fiddling with the onboard controls. I might add in Midi Out anyway since I may come across a cool pattern now and then hihi
Samaepstein
Altitude909 wrote:
Kanutaros wrote:
.. maybe Midi out although I'm not sure how useful the latter would be

..


Pattern backup, extremely useful


Felt the same a about midi out. Installed it any way then realized I was looking at a rudimentary cv to midi step sequencer! Or something.

Currently I use two monotribes with midi. (Thanks altitude!,)
The first has midi in and out going to a juno106. That way I can input my sequence with the Juno keyboard and then have the monotribe send the midi sequence back to the Juno! This was a huge leap for me as I had never figured a way to do this with my computer previously.this mt also has separate drum outs for dub mixing.

The second has midi input from a small midi keyboard and midi out used only as clock to a tr505.

Really ties the room together

This set up has been very inspirational for me. With all of the effects I run with it I am constantly surprised at the sound I get out of these "toys" Rockin' Banana!
Kanutaros
Samaepstein wrote:
Altitude909 wrote:
Kanutaros wrote:
.. maybe Midi out although I'm not sure how useful the latter would be

..


Pattern backup, extremely useful


Felt the same a about midi out. Installed it any way then realized I was looking at a rudimentary cv to midi step sequencer! Or something.

Currently I use two monotribes with midi. (Thanks altitude!,)
The first has midi in and out going to a juno106. That way I can input my sequence with the Juno keyboard and then have the monotribe send the midi sequence back to the Juno! This was a huge leap for me as I had never figured a way to do this with my computer previously.this mt also has separate drum outs for dub mixing.

The second has midi input from a small midi keyboard and midi out used only as clock to a tr505.

Really ties the room together

This set up has been very inspirational for me. With all of the effects I run with it I am constantly surprised at the sound I get out of these "toys" Rockin' Banana!

That sounds like a great idea. I think I could make use of it by using Midi In and controlling the tribe with a keyboard to edit the onboard pattern live and have the midi out send data to the computer to record the session and tweak it a bit hyper

I also noticed something about the monotribe today. Much like how you can set the monotron's LFO switch between pitch and cutoff to control both, I can sort of mix the triangle and ramp waveforms on the monotribe to get a new sound although you have to hold the switch in place. Sounds like I could replace that switch for three pots and get more sounds.

Yay for analog stuff nanners
igormpc


tenori on with a simple beat, sending midi clock to monotribe midi in (amazing machines kit) --
monotribe sending midi clock out to acidlab autobot, clocking its sequencer --
autobot sending cv + gate to modular and monotribe via sync in...

i can record cv sequence on monotribe, disconnect sync in and keep midi clock in advancing the seq, muting some steps, reconnecting to sync in to receive again cv + gate info from autobot...

what i really would like is a switch that i could use on monotribe, to feed some cv when i want without having to disconnect it from sync in... hmmm.....
george2013
Altitude909 wrote:
$40 including the two TRS to DIN5 midi cables

I am sorry, but $40 for one optoisolator and two connectors is too expensive IMHO. Here is the link to Monotribe USB MIDI extention for only $25 http://www.altmustech.com/um-q110.html
radiokoala
Hey guys, does anyone know the following: I soldered a DIN SYNC to 3.5mm cable for syncing monotribe/modular with my VA.

But I assume DIN SYNC and MIDI are different things - is it correct?

That's what I did:



However no clock out. Does MIDI work differently from DIN SYNC? If so, is there still maybe a way to extract a clock out of it - like a different pin?

Much thanks.
Altitude909
george2013 wrote:
Altitude909 wrote:
$40 including the two TRS to DIN5 midi cables

I am sorry, but $40 for one optoisolator and two connectors is too expensive IMHO. Here is the link to Monotribe USB MIDI extention for only $25 http://www.altmustech.com/um-q110.html


Who asked you? The whole reason I started selling kits was ppl were selling them for twice what I ask and someone dared me to come up with something better. To hand stuff a SMD board, make a wire harness, parts, and two custom midi cables plus time to test is why I charge what I charge

I'm sure that your kit will do well for all the ppl that have a MT and a mill on hand to make a square hole like that..

And dont think you're being slick spamming two boards I post on with your wares btw.
Altitude909
radiokoala wrote:
Hey guys, does anyone know the following: I soldered a DIN SYNC to 3.5mm cable for syncing monotribe/modular with my VA.

But I assume DIN SYNC and MIDI are different things - is it correct?

That's what I did:



However no clock out. Does MIDI work differently from DIN SYNC? If so, is there still maybe a way to extract a clock out of it - like a different pin?

Much thanks.


Two completely different things, not even the same pin out. If you already have an analog clock like SYNC24 available, the easiest way to sync the MT would be some form of clock divider. Makes no sense to convert to midi, just keep it analog and use the sync input
george2013
I am sorry, but you are wrong, I am not a spammer, just the same user as others smile
Altitude909
george2013 wrote:
I am sorry, but you are wrong, I am not a spammer, just the same user as others smile


right.. your first and only post on this board (as well as other boards) is promoting the same product, that makes you a spammer.
george2013
Altitude909 wrote:
george2013 wrote:
I am sorry, but you are wrong, I am not a spammer, just the same user as others smile


(as well as other boards)

Which exactly? I didn't know about it hihi
reignbear
playing the monotribe from the op-1 and running it through the phone effect is one of my new favorite things, but it would be even cooler if i could ust send the waveform out through the op-1 and back into the monotribe to send through the filter VCA. is there a way to do this?
mrand
Hi I'm wondering if anyone can identify where I might be able to tap the LFO from my monotribe. I've probed around the LFO waveform selection switch and couldn't find anything. My makeshift probe might not have been good - I don't really know what I'm doing... (I can't even figure out if I'm posting this in the right place)

I've had good success with all the easy drum mods, the vco out, and the vco mute that people are sharing.

Thanks!
Kanutaros
mrand wrote:
Hi I'm wondering if anyone can identify where I might be able to tap the LFO from my monotribe. I've probed around the LFO waveform selection switch and couldn't find anything. My makeshift probe might not have been good - I don't really know what I'm doing... (I can't even figure out if I'm posting this in the right place)

I've had good success with all the easy drum mods, the vco out, and the vco mute that people are sharing.

Thanks!

Isn't the LFO digital? I'm guessing that's why it's controllable by MIDI (a DAC is probably used though, so I could be wrong).

Also, concerning the BD and SD decay mods, I've found that the 100k linear pots are rubbish at this, but covers the whole range so how do the 100k log pots behave? I was hoping its logarithmic resistance curve would give me a more linear adjustment.

What value capacitors did people use to extend the SD Noise Decay and HH Decays?
mrand
Yes I suspected it might be digitally generated. Nevertheless, wouldn't it have to end up as a varying voltage somewhere (like you suggested[/quote], post DAC)? Like to modulate the VCF for example? I figured maybe it could be grabbed there, conditioned (amplified?), and then send outboard. I'm new at this stuff though, so I could be out to lunch.

I haven't tried pots with the decay mods, but did hear someone elses with a lin pot on bd decay, and yes, it sucked - only really sounded good at one point, kind of defeating the point of a pot.

I just tested mine with caps and resistors.
I don't remember what caps I tested, but I'll check later and post it here. (stuff is at school)
Kanutaros
mrand wrote:
Yes I suspected it might be digitally generated. Nevertheless, wouldn't it have to end up as a varying voltage somewhere (like you suggested, post DAC)? Like to modulate the VCF for eg? I figured maybe it could be grabbed there, conditioned (amplified?), and then send outboard. I'm new at this stuff though, so I could be out to lunch.

I haven't tried pots with the decay mods, but did hear someone elses with a lin pot on bd decay, and yes, it sucked - only really sounded good at one point, kind of defeating the point of a pot.

I just tested mine with caps and resistors.
Caps did better things to the hat and snar, lengthened decay if i remember correctly.


OK thank you.

KORG hasn't and won't be posting the rest of the schematics for MT, so I think it might be quite tedious probing out the actual LFO, but since the VCO is an actual VCO and not DCO, so there's a voltage somewhere.
mrand
re caps for extending decays on snar and hh: you should check out this post from playthatbeat:

http://www.mrspring.info/vbulletin/showthread.php?p=9673

This is where I got my info from, I'm petty much just bumbling around trying to copy other people suggestions!
Kanutaros
mrand wrote:
(So, I'm having a really hard time figuring out how to properly quote someone else in this forum - so that the conversation is clear. Sorry about all the mess above!)

re caps for extending decays on snar and hh: you should check out this post from playthatbeat:

http://www.mrspring.info/vbulletin/showthread.php?p=9673

This is where I got my info from, I'm petty much just bumbling around trying to copy other people suggestions!

Thank you very much. I saw the video and really wanted that sound.

A touch of SD Frame and a boomier bass and longer hats. mmmmm

Or completely turn off SD Noise and let the frame work some magic.

EDIT: I've just been playing around with the longer decays, man this is starting to sound good. I think adding up to 500nF of caps (just a bunch of #102 caps in parallel) can give some really nice decay. I see what the post said about the longer snare noise sounds. It's kind of a dull pssssh sound not heard anywhere else. Variable capacitors might be something to consider, although I doubt they would fit on the front panel.
vstace
Almost done with all my mods.

http://www.youtube.com/watch?feature=player_embedded&v=A-WPMEa9ZKY
Samaepstein
vstace wrote:
Almost done with all my mods.

http://www.youtube.com/watch?feature=player_embedded&v=A-WPMEa9ZKY


Badass!
far gon
Samaepstein wrote:
vstace wrote:
Almost done with all my mods.

http://www.youtube.com/watch?feature=player_embedded&v=A-WPMEa9ZKY


Badass!


SlayerBadger!


seconded! giving me some motivation to finally get to modding mine Rockin' Banana!
Kanutaros
So is there any way of modding monotribe with a GLIDE function? As far as I know I can't find a CV out which I can modify to 'delay' the pitch change. I think I can mod the ribbon controller for this, but that will mean it will only work at NARROW and WIDE modes which means completely out of tune melodies.

The only viable solution I have in mind is to mod a little keyboard into a CV/GATE controller and put the glide function on there, but I'd prefer it to all be on the monotribe itself...

I think if we also manage to find the LFO out then I can construct something to tune the LFO such that it can be routed back into the mix to give polyphony using MIDI, at accurate pitch. I was thinking an Arduino chip to process the pitch to convert to its corresponding 12-bit binary word into a 12-bit DAC back into the mix.
a7thson
Kanutaros wrote:
So is there any way of modding monotribe with a GLIDE function? As far as I know I can't find a CV out which I can modify to 'delay' the pitch change.


A slew module (module as in modular) that you could trigger on demand might be worth looking into here, otherwise the only option on a MIDI-fied MT is pitch bend -- I was trying to cook up something in Reaktor but that is not a very portable solution either. MIDItribe is limited but far more crippled by the fact it does not transmit or receive Cutoff or Resonance very frustrating so you have to fake it with a one-shot LFO and thus lose LFO modulation for other purposes. It's a neat device, and makes great noises, but quite simply it's not a 303 & will always be limited to real-time tweakage unless someone hacks in firmware support or Korg graces us with another surprise upgrade.

edit: hell, easier option - drive it with a 303/x0xbox/Revolution/whatever that has CV out...
Kanutaros
a7thson wrote:
Kanutaros wrote:
So is there any way of modding monotribe with a GLIDE function? As far as I know I can't find a CV out which I can modify to 'delay' the pitch change.


A slew module (module as in modular) that you could trigger on demand might be worth looking into here, otherwise the only option on a MIDI-fied MT is pitch bend -- I was trying to cook up something in Reaktor but that is not a very portable solution either. MIDItribe is limited but far more crippled by the fact it does not transmit or receive Cutoff or Resonance very frustrating so you have to fake it with a one-shot LFO and thus lose LFO modulation for other purposes. It's a neat device, and makes great noises, but quite simply it's not a 303 & will always be limited to real-time tweakage unless someone hacks in firmware support or Korg graces us with another surprise upgrade.

edit: hell, easier option - drive it with a 303/x0xbox/Revolution/whatever that has CV out...


If only the monotribe came with test points like the monotron, I could just use a simple programming environment and make it really powerful, despite digital constraints.

Actually, that's something I should do with my monotron once the soldering iron arrives. Been messing with Arduino for a while so there's some fun to be had (provided I'm under 30kB).
a7thson
Kanutaros wrote:

Actually, that's something I should do with my monotron once the soldering iron arrives. Been messing with Arduino for a while so there's some fun to be had (provided I'm under 30kB).


hmm... Monotron -> Monotribe an option?

Building a look-ahead step sequencer in Reaktor is harder than I thought. But it's converting the frequency difference into discrete pitch change messages to cleanly sweep to the freq that will be the hard part.
Kanutaros
a7thson wrote:
Kanutaros wrote:

Actually, that's something I should do with my monotron once the soldering iron arrives. Been messing with Arduino for a while so there's some fun to be had (provided I'm under 30kB).


hmm... Monotron -> Monotribe an option?

Building a look-ahead step sequencer in Reaktor is harder than I thought. But it's converting the frequency difference into discrete pitch change messages to cleanly sweep to the freq that will be the hard part.

I always felt my monotron to be a dumb toy with big sounds. It's interface is limiting and with the amount of capabilities it has, I really want to make the most out of it.

So yeah, a step sequencer is a must have, along with maybe some simple drum sounds triggered by the sequencer, ending up with a nice little open-source monotribe.

I'm trying to see if I can make it update from a simple audio file like the tribe, that's a real neat function from KORG which I'm all for.
Lyncaster
Lyncaster wrote:
i just toggled around in there, and now, it will turn on fine, but wont output sound, at all.

Anyone?
mrand
otoskope wrote:

The drum audio separate outs are a bit low level, and I will one day substitute the buffers I added for simple opamp gain stages. Also the triggers are a bit low level for my Bugbrand modular. Although they work perfectly for triggering, they are noticeably weak when used for pinging filters. There's a 9V supply that goes to the Monotripe internal speaker amp, and I'm thinking about using that to power the gain stage to be able to crank it up a bit.

/Palle


Anyone know somewhere to point me to learn how to properly buffer my separate drum/vco/vca outputs? I tried wiring in a TL062 opamp which I supplied with +5v and gnd off the mt board, which works, but I guess I'm loosing the negative part of the swing. Maybe there is a -5v point I can tap on the board already? Also interested in otoskop's idea to use the 9v to power "simple opamp gain stages".

Oh, I also appreciate that Otoskop refers to the synth as "the Monotripe"... yum... tripe! wink

My electronics knowledge is pretty limited, fyi.

Thanks!
mrand
I guess the LFO obviously must come out of the Toshiba TMPM332FWUG (under the ribbon controller). I don't understand if this microcontroller would put out a digital LFO message that goes analog somewhere before vfc/vco modulation, or if it has a DAC inside and it puts an LFO right out from one of its 44(?) pins. Looking at the data sheet I don't think it has any DAC inside, so maybe there is a nearby DAC chip that could have the LFO on it's outputs.

I guess LFO reset would have to be implemented with midi?
Synesthesia
Hey guys, Computer Controlled asked that earlier in the thread but I couldn't locate an answer ...

Is anyone already done \ know where to gate a CV - Gate cable for Analog 4 to monotribe?
Vcs3
Does a custom overlay count as a modification?

[/img]
oscillateur
Tell me more about this custom overlay, it is relevant to my interests smile.
Vcs3
oscillateur wrote:
Tell me more about this custom overlay, it is relevant to my interests smile.


Sure, it's based on the MS20 design, created in Illustrator and then printed with http://www.styleflip.com.

Synesthesia
ah man those are really cool - much better than the yellow V2 overlay !!!
mckenic
Yeah! If you have any spares I know one (perhaps two?) lads in Ireland who would snap em up!!!
Vcs3
Thanks!

I have no spares unfortunately! I only made three :-(
mckenic
thumbs up
Aaron2
Altitude909 wrote:
machetemirage wrote:
Is there a possible "mix" mod for the snare? It would be cool to find a nice combo of frame and noise. I know I could send the two outs to a mixer, but I'm wondering if there is a point on the board that controls the blend for the factory sound....


EDIT: Or the decay mods could just increase or decrease the amount of each... d'oh!


Just wire a pot like a panner


I'm sorry if this question has been answered already, but how exactly do you "wire a pot like a panner"? I'd really be interested to know; I think mixing the snare mods would be a great idea!

Aaron
Altitude909
Output to to the wiper, inputs to the remaining legs. Middle position is 50/50 mix
Aaron2
Altitude909 wrote:
Output to to the wiper, inputs to the remaining legs. Middle position is 50/50 mix


Thanks for the answer! SlayerBadger!
Vcs3
Vcs3 wrote:



For personal use only, Monotribe MS20 style overlay in Illustrator format: https://www.dropbox.com/s/1v1hq7xub3zy06e/Monotribe_MS20_Final.ai

Enjoy!
nrvana8775
I'm gonna grab one of these soon. Seen so many cool mods since they first came out.

Or maybe getting the volcas. IDK!
Aaron2
Altitude909 wrote:
Output to to the wiper, inputs to the remaining legs. Middle position is 50/50 mix


OK, if someone could offer some assistance, I'd really appreciate it. I've done tons of soldering, having fixed dozens of vintage tube and transistor radios (my former hobby). But synth modding is still fairly new to me. My proudest accomplishment thus far is successfully performing the "Moog Slayer" and similar mods on my Korg Poly 800s (I've done a few of these, in fact -- all turned out great).

But for that project, I had really clear instructions. For these Monotribe mods, not so much. And I have to admit that I don't have a great background in electronics, but I can solder, as I said, and I follow directions really well. grin

With that said, please tell me precisely how to wire up a pot for the bass-drum decay. In other words, break it down like I'm a five-year-old. I know that I need to solder a wire to the PCB where it says "BD Decay," for example.

What do I do next? To which pin on the pot does that wire go? I know that I also need to connect a wire to a ground pad on the PCB in series with a 330-ohm resistor. To which pin do I connect that wire? Do I need to do anything else to get this mod to work correctly?

[By the way, this past weekend, I tried to wire up a 5KA (audio) pot to the BD decay. Sounded horrible at highest resistance. I guess I need a 1KA?]

Thanks in advance!

Aaron
Aaron2
<cricket sfx>

Anyone?
yinsen
Vcs3 wrote:
Vcs3 wrote:



For personal use only, Monotribe MS20 style overlay in Illustrator format: https://www.dropbox.com/s/1v1hq7xub3zy06e/Monotribe_MS20_Final.ai

Enjoy!


that link and file seems to be a blank illustrator canvas... is it just my computer? seriously, i just don't get it
GNSDG
Gentleman, awesome work here. I'm looking into rolling my own interface that to accommodate the sync function as well.

Did you use these jacks, or similar ones?

http://www.mouser.com/Search/ProductDetail.aspx?R=161-7900-EXvirtualke y11180000virtualkey161-7900-EX
Altitude909
GNSDG wrote:
Gentleman, awesome work here. I'm looking into rolling my own interface that to accommodate the sync function as well.

Did you use these jacks, or similar ones?

http://www.mouser.com/Search/ProductDetail.aspx?R=161-7900-EXvirtualke y11180000virtualkey161-7900-EX


That's what I use on my midi kits, you need something with a long thread (4.5mm) or it wont clear the aluminum sides
ato
Hi all.
Thanks for all the great info here! This forum got me buying a second hand MT extremely cheap and grabbed the tools I needed for modding.
Did a bit of woodwork too for the side panels.
Being a first time solder not just fried that F1 fuse myself on the battery board in the first ten minutes (thanks Altitude for the solution), but almost finished most of the mods successfully. (VCO mute, Decay switches and pots, snare snappy pot, kills for each drum sound and MIDI) Working great for first try and looks acceptable!

I'd love to do the drums to VCF switch and I have the DRUMS signal from the rhythm pot but do not know where to send that too. I was thinking of the interface board, somewhere around the aux-in but no luck (this is when fried the fuse...).
Can somebody please help with the soldering point? Is it ok just to solder there or a resistor needed too?

Also because I was so excited, successfully melted the hihat out solder point from the board and have no idea how to stick it back. Any chance that I'll be able to fix a hihat out there? (I can survive without it, will do the next MT mod perfect, HAHA) I see a tiny hole very close to it, would that do any good for me?

Again, thanks for all the great info!
mckenic
Hey ato!

Welcome to Muffs! Im NOT saying this is the cleverest thing or even recommending anyone do it but if it were ME (and keep in mind Im no expert here...)...

I'd remove some of the pcb mask on the trace leading up to the Hi Hat point - scrape off the green gunk on the 'road' up to the Hi Hat point until you see copper underneath - and solder there!

thumbs up
ato
Yeah, I may leave it as it is until I have more experience on other boards. :(
Thanks anyway!
GNSDG
Altitude909 wrote:
GNSDG wrote:
Gentleman, awesome work here. I'm looking into rolling my own interface that to accommodate the sync function as well.

Did you use these jacks, or similar ones?

http://www.mouser.com/Search/ProductDetail.aspx?R=161-7900-EXvirtualke y11180000virtualkey161-7900-EX


That's what I use on my midi kits, you need something with a long thread (4.5mm) or it wont clear the aluminum sides


Altitude909, just to be clear, you're saying those won't work bc there's not enough threading, right? Anyone have a source for jacks w more threading?

Man, if I could control my MT w my Touch Sequencer...
Altitude909
GNSDG wrote:
Altitude909 wrote:
GNSDG wrote:
Gentleman, awesome work here. I'm looking into rolling my own interface that to accommodate the sync function as well.

Did you use these jacks, or similar ones?

http://www.mouser.com/Search/ProductDetail.aspx?R=161-7900-EXvirtualke y11180000virtualkey161-7900-EX


That's what I use on my midi kits, you need something with a long thread (4.5mm) or it wont clear the aluminum sides


Altitude909, just to be clear, you're saying those won't work bc there's not enough threading, right? Anyone have a source for jacks w more threading?

Man, if I could control my MT w my Touch Sequencer...


those DO work. They have a 4.5mm length threaded section which will clear the thickness of the side of the MT and allow the nut to engage so it does not hang up the 3.5mm jack. The only other ones I have seen with a long enough threaded part are the Erthenvar ones but AFAIK, those only come in mono and you need stereo for the MIDI
GNSDG
Altitude, awesome--thanks so much.
Keyman
You could try the procedure to refresh/upgrade the firmware in case it got corrupted? Otherwise, look at what you might of touched or moved...

Lyncaster wrote:
Lyncaster wrote:
i just toggled around in there, and now, it will turn on fine, but wont output sound, at all.



Anyone?
Keyman
read a related forum that said something about the cpu having a routine to continually temperature compensate the pitch...supposedly the slew/portamento type mod would interfere with that?


Kanutaros wrote:
a7thson wrote:
Kanutaros wrote:
So is there

any way of modding monotribe with a GLIDE function? As far as I know I can't find a CV out which I can modify to 'delay' the pitch change.


A slew module (module as in modular) that you could trigger on demand might be worth looking into here, otherwise the only option on a MIDI-fied MT is pitch bend -- I was trying to cook up something in Reaktor but that is not a very portable solution either. MIDItribe is limited but far more crippled by the fact it does not transmit or receive Cutoff or Resonance very frustrating so you have to fake it with a one-shot LFO and thus lose LFO modulation for other purposes. It's a neat device, and makes great noises, but quite simply it's not a 303 & will always be limited to real-time tweakage unless someone hacks in firmware support or Korg graces us with another surprise upgrade.

edit: hell, easier option - drive it with a 303/x0xbox/Revolution/whatever that has CV out...


If only the monotribe came with test points like the monotron, I could just use a simple programming environment and make it really powerful, despite digital constraints.

Actually, that's something I should do with my monotron once the soldering iron arrives. Been messing with Arduino for a while so there's some fun to be had (provided I'm under 30kB).
Mr_Sulcus
Hello all, I wonder if someone would be able to help with the mods to my monotribe.

Following a lot of reading (mainly here - excellent work!) I did the vco mute, added phono sockets to separate the drums from the synth, and put the BD decay, SD noise decay and HH decay on separate on-off-on toggles, aiming to get two different sounds for each in addition to the stock. Its sort of worked, got a snappier hat and a longer splash type sound, and two boomier bass drums, but I can't figure out how to get the snares right - what values are people using? I tried a 103k cap, and 100 n as described http://www.mrspring.info/vbulletin/showthread.php?2631-MOD-Korg-Monotr ibe-Modification&p=9673#post9673 with no luck (I did at one point get just the frame sound, which I liked, but can't get it back). Any suggestions wouldbe gratefully received!

I've also got a noise present when both volume pots are at minimum, it sounds like a synth pattern being played when there is nothing programmed, and goes away when you turn either pot slightly, or keep the lfo int all the way clockwise. Its unaffected by anything apart from the vfc knobs, and although I didn't do any mods to that, it wasn't there before I messed about with a soldering iron! Could it be an issue with grounding perhaps?

Thanks in advance for any help, I'm new to this and learning as I go (hopefully without destroying much).
max445
Hey guys, thanks a lot for all that research and documentation!
Even though my electronics-skill must be around 1 out of ten, with this forums help i've been able to install several mods on my 'tribe literally without any problems.

One thougt has come to my mind though wich i didn't find in this forum by today (have i missed it maybe??)

When unpacking the Monotribe i almost immediately used the provided sync cable to feed the signal from the phones-out back into the audio in wich some kind of overdrives the filter circuit. I leraned that there even is a small device made by the company from brazil wich also builds the 75$ midi i/o kit:

http://amazingmachines.com.br/products_nastymono.html

Basically its a pot and two cables, so if i wanted to biuld this on my own, wich potentiometer would i wanna be using? i happen to have a 500k here, would that be a good starting point?

Thanks, keep it up and excuse my english razz
SmashMastrCrush
Is it relatively easy to get in there and solder? or is it kinda tight? Dead Banana
zembla
Pretty excited to get my hands on one of the CV interfaces for my monotribe.
Jaytee
zembla wrote:
Pretty excited to get my hands on one of the CV interfaces for my monotribe.


I didn't see anything about this on the last page or two.... What exactly do you mean?

The Monotribe has pitch CV/gate natively now, but if there's a way to get more CV control than that, I'm interested.
MountainDew420
Ok, so i attempted to add midi in to my monotribe. i tested it and got nothing. after double checking my circut and connections i noticed that i had connected one of the wires to the wrong pin on the serial port. after corrected my mistake i went to test it and it wouldnt turn on. anyone have any idea what could have happend?

there was also a significant lapse in time between my first test and attempted second test, and in that time i lost a few of the screws. could it be that all of the screws need to be in place to complete the ground loop?
Altitude909
MountainDew420 wrote:
Ok, so i attempted to add midi in to my monotribe. i tested it and got nothing. after double checking my circut and connections i noticed that i had connected one of the wires to the wrong pin on the serial port. after corrected my mistake i went to test it and it wouldnt turn on. anyone have any idea what could have happend?

there was also a significant lapse in time between my first test and attempted second test, and in that time i lost a few of the screws. could it be that all of the screws need to be in place to complete the ground loop?


No, screws wont cause that. Chances are you are shorting 3.3v to ground somewhere, remove the mod and check if it still works
MountainDew420
i removed the mod and it still doesn't turn on. it looks like i might have accidentally bridged the bottom two pins on the serial connector, but i dont have a multimeter handy so im not sure. could that prevent it from powering on?
Altitude909
yeah, bottom two are ground and power. Dont turn it on until you verify that, you are shorting a power rail to ground, it wont boot and not good for the device.
Fladd
Yes i´m totally new hier screaming goo yo Hello.

So, MT synthline can be played with cv in. In my set i play MT synth with A-155 so how can i sync MT drum sequencer at the same time with A-155… I have an 3,5 mm 4pol cable on one side to MT and two 3,5 mm 2 pol cable to A-155, one to “Trigger” an one to “Post Out”…

Thanks.
far gon
thanks to all for this thread!

lots of good info, and i think it is motivating me to finally mod my 'tribes w00t
darenager
Fladd wrote:
Yes i´m totally new hier screaming goo yo Hello.

So, MT synthline can be played with cv in. In my set i play MT synth with A-155 so how can i sync MT drum sequencer at the same time with A-155… I have an 3,5 mm 4pol cable on one side to MT and two 3,5 mm 2 pol cable to A-155, one to “Trigger” an one to “Post Out”…

Thanks.


Can't be done, it is either set to CV/Gate or clock input, you could just clock the A-155 from your MT when it is in CV mode, as it will still send clock out in CV mode. Or what you can do is record the CV from your A-155 into the MT sequencer, although you will still probably want to clock the A-155 from your Monotribe when recording the pattern in, save it, turn off, go into CV setup put it back in clock mode.
Truckfumes
Jaytee wrote:
zembla wrote:
Pretty excited to get my hands on one of the CV interfaces for my monotribe.


I didn't see anything about this on the last page or two.... What exactly do you mean?

The Monotribe has pitch CV/gate natively now, but if there's a way to get more CV control than that, I'm interested.

Say whaaat?!? something wonderful
Thank you very much. On your cue just went to Korg's site..
Sure enough, new Operating system with cv/gate for pitch.
Fabulous! w00t
Jaytee
Yup! It's designed for use with a King Korg (you can plug the TRRS cable directly from one to the other), but it's really easy to build an adapter to break the connections out.
Truckfumes
Jaytee wrote:
Yup! It's designed for use with a King Korg (you can plug the TRRS cable directly from one to the other), but it's really easy to build an adapter to break the connections out.

Right. Or any other CV/gate out type equipment.
I was hoping to sequence the thing with a DarkTime.

So how does the Monotribe handle pitch and gate with only on CV input anyways?

I got the upgrade all done, I just haven't tried it yet. I'm absolutely flattened right now with the flu. My head can not take the drone and squeal of a synth right now. Dead Banana
Thanks again for the heads up. I got lucky reading your post. I try to stay somewhat current with this thread for info about the MT.
Peace.
Jaytee
Truckfumes wrote:
Jaytee wrote:
Yup! It's designed for use with a King Korg (you can plug the TRRS cable directly from one to the other), but it's really easy to build an adapter to break the connections out.

Right. Or any other CV/gate out type equipment.
I was hoping to sequence the thing with a DarkTime.

So how does the Monotribe handle pitch and gate with only on CV input anyways?

I got the upgrade all done, I just haven't tried it yet. I'm absolutely flattened right now with the flu. My head can not take the drone and squeal of a synth right now. Dead Banana
Thanks again for the heads up. I got lucky reading your post. I try to stay somewhat current with this thread for info about the MT.
Peace.


Sorry, I wasn't clear.

The sync in jack (which switches to the CV/gate jack in CV mode) is actually a TRRS connection, so it can carry three signals plus a ground. One is CV, one is Gate, the other is unused. The King Korg comes with special cable that breaks out the TRRS into separate TS connections that are more universally used for CV/gate.

Instead of spending $1k on a King Korg, you can buy a cable and a couple adapters on amazon to accomplish the same thing.

http://www.amazon.com/Hosa-C3M-110-Camcorder-Cable-Feet/dp/B0010CTHKQ/

http://www.amazon.com/Hosa-Female-Mono-3-5mm-Male/dp/B000068O49/
Truckfumes
JayTee you kind of lost me here...
Why did you provide links to RCA/3.5mm adapters and such?
There's no RCA jacks anywhere in the chain.

The OS update datum says simply put the MT in CV mode and connect any device that sends Control voltages.(within the specified volt range).

It seems pretty straight forward. I didn't see any need for adapters in the instructions.
rove74
The monotribe CV input needs a TRRS cable and the only readily available ones terminate in RCA connectors so you will need RCA to 3.5mm/1/8th" adaptors as well. Also be aware that not all TRRS-RCA cables have the same wiring; I use a nokia AV cable I got from ebay and it works fine, but some other standard AV cables will not work.
Truckfumes
rove74 wrote:
The monotribe CV input needs a TRRS cable and the only readily available ones terminate in RCA connectors so you will need RCA to 3.5mm/1/8th" adaptors as well. Also be aware that not all TRRS-RCA cables have the same wiring; I use a nokia AV cable I got from ebay and it works fine, but some other standard AV cables will not work.

Yes, I'm beginning to see that now.
Thanks Rove and Jaytee.
The Circuit Molester
Jaytee wrote:
Truckfumes wrote:
Jaytee wrote:
Yup! It's designed for use with a King Korg (you can plug the TRRS cable directly from one to the other), but it's really easy to build an adapter to break the connections out.

Right. Or any other CV/gate out type equipment.
I was hoping to sequence the thing with a DarkTime.

So how does the Monotribe handle pitch and gate with only on CV input anyways?

I got the upgrade all done, I just haven't tried it yet. I'm absolutely flattened right now with the flu. My head can not take the drone and squeal of a synth right now. Dead Banana
Thanks again for the heads up. I got lucky reading your post. I try to stay somewhat current with this thread for info about the MT.
Peace.


I was wondering if anyone has synced a Monotron's oscillator to the Monotribes oscillator output.
I this possible?

Sorry, I wasn't clear.

The sync in jack (which switches to the CV/gate jack in CV mode) is actually a TRRS connection, so it can carry three signals plus a ground. One is CV, one is Gate, the other is unused. The King Korg comes with special cable that breaks out the TRRS into separate TS connections that are more universally used for CV/gate.

Instead of spending $1k on a King Korg, you can buy a cable and a couple adapters on amazon to accomplish the same thing.

http://www.amazon.com/Hosa-C3M-110-Camcorder-Cable-Feet/dp/B0010CTHKQ/

http://www.amazon.com/Hosa-Female-Mono-3-5mm-Male/dp/B000068O49/
darenager
Or you could get one of my cute breakout boxes hihi

h4ndcrafted
I had a Monotribe , but sold it. I really miss it actually, just bc it was so easy to get vowel sounds and rises and sweeps to layer. It was really quick to work with.

I'm thinking of getting an MS20 mini though, any of you have both, is it the exact same filter ?

Do you think it wouldn't make a replacement bc the Monotribe is easier to tweek , do you think what the Monotribe does relies on its seq a lot so I won't get what I need from the MS20 ?

or do you think I will get a lot better vowel sounds out of the MS20 too ?

In short is it worth having both ?

I did this video and you can see the sort of sounds I want to have again at 1:01

Kingnimrod
the Monotribe and MS-20 mini are different beasts.

Yes, the filter is supposedly "the same" but only the LPF. The MS-20 mini also has the HPF and dialing both in makes for some very nasty sounds.

I think it's worth having both if you can afford it. The Monotribe is nice for drones and minimal sequencing. The MS-20 is fun for more advanced sound shaping.

Of course, none of it is as fun as playing with real modular gear.
darenager
I have both, 7 Monotribes and 1 MS20 mini and a vintage MS10, very little overlap, in fact the Monotribe filter is much closer to the vintage MS10 than the MS20 mini. I think it is because the HPF in the MS20 is always rolling off some of the beef even when fully open. Interestingly the Monotribe and MS10 filters can do very nice barberpole type rippling, whilst the mini does not do it nearly as pronounced.

Of course the Monotribe also has the huge advantages of low cost, portability and standalone minimalist sofa grooving hihi

Whilst I'd agree that the modular offers many more possibilities, I'd say the fun to be had with the Korgs is equivalent but different, with immediacy being an often overlooked advantage.

The Monotribe is the wigglers harmonica/acoustic guitar hihi
Truckfumes
I updated my MT to OS V2.1.
I checked the MT to see that the update was successful.

So today I tried it out and I can't get it to work.
I turn on the power while pressing gate and snare.
At that point Rec and Flux LEDS blink and SN and HH stay lit up.

I hooked up the white RCA jack with adapter to gate
and likewise the yellow to CV.
This is on my Darktime.
I then plug the 3 ring jack into the sync-IN jack of my MT.
I get nothing. I have tried different color combinations with the jacks.
I have pressed LED 1 2 and 3 in different configs. I have wiggled all the jacks in and out.
Am I missing something?
Truckfumes
Ok it works now. Don't know what I did. I hit the flux and record buttons and turned them off and wiggled more cables around.

This is great! Works exactly as advertised. Sequences sharply and accurately.
This is fun!
darenager
I made some Monotribe mod vines

Drum mods

https://vine.co/v/hQYD2QVhPJW
https://vine.co/v/hQY35Ol37OJ
https://vine.co/v/hQYLVzad1LJ

VCO mod 

https://vine.co/v/hQYphWUU3uV
https://vine.co/v/hQYD7Xq6WHv
https://vine.co/v/hQYjxB9LdTU
https://vine.co/v/hQYIDUm5a0q
https://vine.co/v/hQYP7V7udBg
https://vine.co/v/hQYLiEqIO9U

With 303
https://vine.co/v/hQ3baXzV57n
https://vine.co/v/hQ3MdQqIUMn
https://vine.co/v/hQ3i3aVOWDt
https://vine.co/v/hQ3JjD9dm6b
CeeJay
@darenager

Great! Would you tell us your capacitor and resistor values for the drum mods?
Or is this your secret?
mckenic
Just spotted your vid on Matrix Daren! WICKED stuff!
Very interested thumbs up
darenager
Cheers, the drum boards have nearly all gone but got a fair few of the VCO boards left, plenty of Midi kits.

Note the AM miditribe kit takes up a lot of room inside the Monotribe, so it might be necessary to place it elsewhere/external if fitting some of my mods.
mckenic
Thanks Daren!

I'd be after a VCO board if possible please! I imagine after the holidays now as shipping prolly wouldnt get here till the new year...

Umm - does the VCO board fix the clicky VCA perchance? Will it work with my current MIDI mod - the v1 Amazing Machines midi kit?

Jeez - I'll have put more in to mods than the Tribe originally cost me hihi

Thanks sir thumbs up
Cozmic023
Hiya Daren,

I'm still interested in the VCO & Midi mod Kits.

PM if we can't trade here.....

Cheers
Lee
darenager
PM'd!
Cozmic023
Cheers Daren thumbs up
MountainDew420
MountainDew420 wrote:
i removed the mod and it still doesn't turn on. it looks like i might have accidentally bridged the bottom two pins on the serial connector, but i dont have a multimeter handy so im not sure. could that prevent it from powering on?


Ok so i unbridged the pins and removed the mod, and it still wont turn on. Could i have fried something in there, or blown a fuse prehaps?
nitynite
Hello, I am new to this forum. I am trying to contact Altitude909 about a Monotribe CV breakout box, but I can't pm until I have at least 1 post count. So here it is!

Cheers!

Geoff
nickelnickel9
Bump (because I need to meet the one post requisite to access additional features of this forum--thanks for the knowledge, folks).
nickelnickel9
Muffwiggler's,

I hope the veterans on this board don't mind, but I am bumping this topic again in hopes that someone will be sympathetic/generous enough to take a moment out of her/his day to help a know-nothing like myself with a question about drum decay modifications for the Monotribe.

Briefly...I have been playing music for 25 years, but I am an absolute novice with respect to sound synthesis of any type. Despite my utter ignorance of how synthesizers process sound I must attempt to vindicate myself by attesting to my diligent, albeit slow, dedication to obtaining a more complete understanding of these sounds that I have come to enjoy. In fact, I recently bought altitude909's MIDI kit on eBay and I have been knocking the dust of my Monotribe because I have been playing the shit out of it ever since.

That aside, the crux of my dilemma is--I want to modify the drum portion of my Monotribe, but I don't know what the hell to buy.

I have scoured the pages of this forum, and the internet, for information about which particular parts to buy, but I only end up confusing myself further particularly because I do not understand electrical engineering jargon and abbreviations.

Hopefully, this has not been asked before, but--is there a compiled "grocery list," consisting of links to the particular components necessary for the drum modifications exemplified by, for instance, the modifications of altitude909 or darenager?

So, no disrespect to those of you who obviously paid attention during math class (I admire your knack for numbers considering that I can barely add) and I apologize in advance for making such a request on my second post, but I genuinely feel that my appreciation for DIY will come via a hands-on application (an experienced friend will be holding my hand during installation in exchange for a couple of 40's of Mickey's) experience. I am just dependent upon prior wisdom to point me in the right direction.

Thank you in advance for your time and knowledge. In the meantime, I will be drooling on myself and eating crayons whilst I hopefully await for a response.

En solidaridad,
Cal
darenager
It depends on what you want, some people use pots like 1k for kick, 1k for snare, 4m7 for snare noise, 4m7 for hats.

What I found was that pots gave little variation over the range of the pot, so I designed a drum mod pcb with switches, so I have a choice of 3 kicks, 3 snare body, 3 snare noise, 3 hat. Note that the 3 sounds for each INCLUDES the stock sound, so it gives 2 alternate versions. With the snare though because the noise and body each have switches 8 different snare sounds are possible by different combinations of switch position.

If you want to get into diy then have a look at some of the info posted earlier in this thread and at the various youtube videos on monotribe drum mods.
Altitude909
darenager wrote:
..
What I found was that pots gave little variation over the range of the pot, so I designed a drum mod pcb with switches, so I have a choice of 3 kicks, 3 snare body, 3 snare noise, 3 hat. Note that the 3 sounds for each INCLUDES the stock sound, so it gives 2 alternate versions. With the snare though because the noise and body each have switches 8 different snare sounds are possible by different combinations of switch position.

..


+1. Pots sound like a good idea but in practice you're only going to be using them in 3 positions anyway since the response is not monotonic. If I was going to do another box, I wouldnt do the pots again
nickelnickel9
darenager wrote:
It depends on what you want, some people use pots like 1k for kick, 1k for snare, 4m7 for snare noise, 4m7 for hats.

What I found was that pots gave little variation over the range of the pot, so I designed a drum mod pcb with switches, so I have a choice of 3 kicks, 3 snare body, 3 snare noise, 3 hat. Note that the 3 sounds for each INCLUDES the stock sound, so it gives 2 alternate versions. With the snare though because the noise and body each have switches 8 different snare sounds are possible by different combinations of switch position.

If you want to get into diy then have a look at some of the info posted earlier in this thread and at the various youtube videos on monotribe drum mods.


First off, thank you very much for taking the time to reply to my question. I appreciate it. Since I'm so new to synthesis I have not developed a firm preference of switches over knobs or vice versa (this is conditioned upon the task at hand of course).

For my purposes, I am primarily interested in having that deep "808" analog kick as I typically have family and friends over on the weekend to grill, box, and play music. The youngsters in my neighborhood are interested in making hip hop beats and I think they would enjoy the hands-on experience of designing their own sounds through the Monotribe's interface.

I have seen your kits on eBay, and your videos, and I must admit that I have been tempted to pick one up, but I wasn't sure how low the bass drum was (I've had pretty terrible speakers up until a day ago).

On a side note, considering that I have purchased altitude909's MIDI kit, would you recommend your CV/Gate modification for someone like me? I enjoy creating electronic music as well.

As for the DIY, I am taking baby steps by purchasing some stuff from BuildYourOwnClone. I enjoy math and science and have the utmost respect and admiration for those who can do it, but it's slow learning process for me because it has always been very difficult for me to retain numerical information for some reason! However, I am not giving up yet!
nickelnickel9
Altitude909 wrote:
darenager wrote:
..
What I found was that pots gave little variation over the range of the pot, so I designed a drum mod pcb with switches, so I have a choice of 3 kicks, 3 snare body, 3 snare noise, 3 hat. Note that the 3 sounds for each INCLUDES the stock sound, so it gives 2 alternate versions. With the snare though because the noise and body each have switches 8 different snare sounds are possible by different combinations of switch position.

..


+1. Pots sound like a good idea but in practice you're only going to be using them in 3 positions anyway since the response is not monotonic. If I was going to do another box, I wouldnt do the pots again


Firstly, as was the case with your brother in synthetic arms, darenager, I would like to thank you for taking the time to respond to me. I am greatly appreciative of it.

I trust your professional opinion and will adopt your recommendation of the switches over the pots. Especially since you've spent considerable time with your modified Monotribe and are very familiar with it.

By the way, thank you very much for the MIDI kit! I am really enjoying it! Considering that you have some customer loyalty here and I am seriously considering picking up darenager's drum modification kit with the few extra bucks I have saved to get some new music stuff--could you offer any other recommendations for customizing my Monotribe? Thank you again.
darenager
Pots vs Switches is down to preference really. With pots you are a bit more limited in that all you get is a smallish range of actual difference, but with switches, due to the way the drums are created the switches will retrigger the drum when switched, not really a problem if you switch when a drum is being triggered, but something to be aware of.

On my mod the bass drum is pretty nice, I actually prefer it to the Volca Beats kick, but to hear it properly then headphones or half decent speakers are needed. It is pretty deep with a long decay when switch is down.

CV Gate breakout is only useful if you have some other CV gear really.

Other mods worth trying are VCO and drum mutes which I explained earlier in this thread, basically a toggle switch from each drum output pad or VCO pad to ground, very useful.
nickelnickel9
darenager wrote:
Pots vs Switches is down to preference really. With pots you are a bit more limited in that all you get is a smallish range of actual difference, but with switches, due to the way the drums are created the switches will retrigger the drum when switched, not really a problem if you switch when a drum is being triggered, but something to be aware of.

On my mod the bass drum is pretty nice, I actually prefer it to the Volca Beats kick, but to hear it properly then headphones or half decent speakers are needed. It is pretty deep with a long decay when switch is down.

CV Gate breakout is only useful if you have some other CV gear really.

Other mods worth trying are VCO and drum mutes which I explained earlier in this thread, basically a toggle switch from each drum output pad or VCO pad to ground, very useful.


Nice! I can hear it now! I see that your drum mod is on sale. How can I get one?

As far as the CV stuff goes, I have a Microbrute and I've tried setting it up and I got something going a while back, but I'm not sure if I'm doing it right. I would need to invest more time into understanding that function.
darenager
You can email me via the blog re the drum mod.

For CV you need to make sure you have the update, then set up the CV as per the Korg doc, for the Microbrute you want to set it for v/oct and positive gate.
lerba
Hi! Thanks for the awesome info & discussion!

I was wondering if anyone here has used the monotribe cv pitch & gate in with arturia microbrute or minibrute? I got the nokia rca breakout cable and gate signal works fine. I have some problems getting correct pitch though.

There's a change on pitch on both modes on the MT when pressing different keys on my microbrute but it's nowhere nearly accurate. Almost sounds as if the pitch was inverted. Is this possible? I've also tried different pitch ranges on the MT.
Rcmonkee
Hey thanks guys for all the good info on here. I've had my tribe for a couple of weeks now, and it is the funnest piece of gear that I've gotten in awhile. I just ordered a midi kit and I'm also going to do the drum out mods, maybe even a decay mod too.
zmb
lerba wrote:
Hi! Thanks for the awesome info & discussion!

I was wondering if anyone here has used the monotribe cv pitch & gate in with arturia microbrute or minibrute? I got the nokia rca breakout cable and gate signal works fine. I have some problems getting correct pitch though.

There's a change on pitch on both modes on the MT when pressing different keys on my microbrute but it's nowhere nearly accurate. Almost sounds as if the pitch was inverted. Is this possible? I've also tried different pitch ranges on the MT.


Yeah I've gotten them to communicate via CV. DId you do the pitch calibration procedure on the monotribe? There's a procedure for it in the monotribe update documentation PDF that should be in the same zip file containing the monotribe OS update.
lerba
zmb wrote:
lerba wrote:
Hi! Thanks for the awesome info & discussion!

I was wondering if anyone here has used the monotribe cv pitch & gate in with arturia microbrute or minibrute? I got the nokia rca breakout cable and gate signal works fine. I have some problems getting correct pitch though.

There's a change on pitch on both modes on the MT when pressing different keys on my microbrute but it's nowhere nearly accurate. Almost sounds as if the pitch was inverted. Is this possible? I've also tried different pitch ranges on the MT.


Yeah I've gotten them to communicate via CV. DId you do the pitch calibration procedure on the monotribe? There's a procedure for it in the monotribe update documentation PDF that should be in the same zip file containing the monotribe OS update.


That was it. Can't believe I missed that part. Thanks!
lerba
edit: double post
zmb
lerba wrote:
zmb wrote:
lerba wrote:
Hi! Thanks for the awesome info & discussion!

I was wondering if anyone here has used the monotribe cv pitch & gate in with arturia microbrute or minibrute? I got the nokia rca breakout cable and gate signal works fine. I have some problems getting correct pitch though.

There's a change on pitch on both modes on the MT when pressing different keys on my microbrute but it's nowhere nearly accurate. Almost sounds as if the pitch was inverted. Is this possible? I've also tried different pitch ranges on the MT.


Yeah I've gotten them to communicate via CV. DId you do the pitch calibration procedure on the monotribe? There's a procedure for it in the monotribe update documentation PDF that should be in the same zip file containing the monotribe OS update.


That was it. Can't believe I missed that part. Thanks!

Cool, glad i could help
zetathix
Hello, I'm a new user here. Nice to meet you all.

This topic really catch me and make me want to mod my MT too, so I continuously read this topic from page 1 to this page...That's long and I can't understand it all but it's very useful and inspiring. I really appreciate the skills here.

I have just a tiny bit of knowledge about electronic. So I still need some clues. I want to try with decay first. Please help me with this.

1. Can I use a switch-pot for all decay-mod? so I can turn it on-off and make right decay level.

2. Recommend R = 470R ?

3. I try to find some components in local online stores but I do not know about "W" of R. Which one could tell me the suitable number of W?

Sorry if I'm too lack of knowledge. Sorry again for bad english. Thank you very much, in advance... thumbs up
Auxar
I got my hands on some nice gem for all you Monotribe modders.

I think this could be useful wink

cheers! w00t
grenert
Wow, where'd you get this?!!
No "for public release" on them like for the Monotrons.
thumbs up

Can you get Volca schematics? twisted
Altitude909
interesting indeed, the mysterious R195 was for a sample input into the rhythm section?
zmb
zetathix wrote:


1. Can I use a switch-pot for all decay-mod? so I can turn it on-off and make right decay level.

2. Recommend R = 470R ?

3. I try to find some components in local online stores but I do not know about "W" of R. Which one could tell me the suitable number of W?

Sorry if I'm too lack of knowledge. Sorry again for bad english. Thank you very much, in advance... thumbs up


it's been a really long time since i modded the rhythm section so i don't remember anything regarding your first two questions but in response to 3. for these purposes 1/4W or 1/8W is fine. WHatever's lowest on the site should work.
darenager
Auxar wrote:
I got my hands on some nice gem for all you Monotribe modders.

I think this could be useful wink

cheers! w00t


Thank you SlayerBadger!
darenager
So there appear to be 2 LFOs, interesting.

Quite elegant how they use a PWM output for note and another for octave, I guess it makes scaling easier and more efficient, 12 values for note and 6 or 7 values for octave, clever.
sequentialx
Auxar wrote:
I got my hands on some nice gem for all you Monotribe modders.

I think this could be useful wink

cheers! w00t


Thanks!

I remember looking for this when I got mine but had since given up!
xtinct
Anyone manage to crack darenager's VCO mod? Something about routing an inactive VCO wave to the active internal one and using a pot to vary the phase? I am willing to exchange info on a simple PWM mod for the square wave for any detailed hints on how this peusdo-FM mod is achieved.
darenager
^ I think you might be getting mixed up with with another mod, my VCO mod is an additional VCO/PLL PCB, basically it is fed from the internal VCO then fed back into the audio path.
lerba


Anyone had success with this click-reduce mod? Basically you just add a cap between ground and that one leg of the chip?
ri0h
lerba : I'm just modding my Monotribe, for now on I just grabbed all the interesting wires from various mods out of the box with a hole on the side, but there is still all the circuits modifications to make.

The click reduction is the only one I did yet (you don't need to wire any pot or switch outside), there's a bit less of click, but it is not that obvious, also the real problem for me was the hard click you had when having a high resonance with the cutoff set pretty low, and the click is still quite present in that case.
neilbaldwin
Here's my Monotribe with distortion mod:



http://marmotaudio.co.uk/blog
mckenic
Woah! Frikkin great idea!!!

I think I need a 2nd 'Tribe for all the mods I put mine thru hihi Darens Osc board, Amazing Machines v1 Midi - dont know if I could FIT this in! Would love to hear how it sounds with the Osc board mod!!!
Cozmic023
Nice mod Neil, sounds amazing....... SlayerBadger!

My Monotribe is pretty maxed out with mods, thanks to Daren.

Cheers
Lee
neilbaldwin
Yeah, I've got Daren's MIDI and oscillator mods in there too hihi (though in the video it's just the 'standard' oscillator output, distorted)

I'll do another recording with some different material. I installed a switch so that you can route either the synth or the drums to the distortion circuit (on it's own output too).
Cozmic023
Cool.

Mines got the Osc, Drum & Midi Mods. Plus i've added a CV/Gate in/out too. (Thanks to Din-Sync)

Cheers
Lee
BugBrand
Just looking, with interest, at the schematic posted on the last page.

Think you should be able to do linear FM input by going to IC13 Pin13.
I'd suggest starting with something like 220-470k, maybe also a DC-blocking cap of 100-470n too.
(haven't at all been paying attention to what's been up in MonoModWorld so excuse me if such has been suggested before..)
will0000
Hi there

First post here... very interesting (long) thread! I'm planning on MIDIfying my monotribe. This may be more of a general DIY question, but can I use a homemade vactrol instead of the optocoupler mentioned in this thread (6n136)? I also have an LTV816 (http://www.mouser.com/ds/2/239/LTV-8x6-201828.pdf) I picked up at a local shop, I'm wondering if that will work as a substitute? thanks
Altitude909
will0000 wrote:
Hi there

First post here... very interesting (long) thread! I'm planning on MIDIfying my monotribe. This may be more of a general DIY question, but can I use a homemade vactrol instead of the optocoupler mentioned in this thread (6n136)? I also have an LTV816 (http://www.mouser.com/ds/2/239/LTV-8x6-201828.pdf) I picked up at a local shop, I'm wondering if that will work as a substitute? thanks

Maybe. Spending the $0.79 on the right part may be a better use of your time than finding out though
marmad
Someone is paying me to fully mod a Monotribe - as I did to some Monotrons back in 2011: https://www.muffwiggler.com/forum/viewtopic.php?t=53496&postdays=0&pos torder=asc&start=0

It should be simple to add extra VCOs, controls, etc, since the analog sections are quite similar to Monotron (in fact, with some simple tweaks, I suspect you could use the schematic I posted over in the Monotron thread to add another waveform). I'll post new schematics here as finished...
marmad
Here's a fairly simple mod: it feeds the EG waveform into the rhythm path with nice results. Each EG setting (saw, square, etc.) generates different accents on the rhythm.

marmad
It seems the activity here has dwindled. Are other MT owners still interested in new mods?

I've developed a true GATE (not SYNC) and 1V/Oct CV outputs and will post schematics if there's interest.
will0000
Yes, definitely interested. I'm also interested in information about/schematics for VCO mods for the monotribe, ie. adding a second oscillator
CeeJay
@marmad: I'm definitely interested in a CV and Gate output! Thank you for posting your mods!
marmad
Ok, will & CeeJay - I've breadboarded a second VCO with PWM and will post the schems for that and the CV/Gate out as soon as I get a chance to draw them up.
marmad
Here's a waveform image of 1V/Oct Pitch CV (1) and Gate Time (2) outputs from Monotribe. As I mentioned earlier, I'm modding this for someone else - if anyone has any suggestions for mods that haven't been done yet, please let me know and I'll see if I can do it and post the schematics.

marmad
I'll be posting schematics (and perhaps some video) for new mods over the coming days (as I find the time to make them), but having just finished looking through this thread, I thought I should post something else first:

There's some misinformation here (and on other sites) about the drum mods. It seems that everyone that has posted about them has done them in (more or less) the same way - and that way is, putting it delicately, not very good. But in any event, despite what you might have read before, it's absolutely possible - and very easy - to wire them for full control via a pot's entire range (from zero to a defined maximum) - with simple, readily-available parts. These circuits can also function as drum mutes - since zero decay or gain can be one end of the range.

If you look at the Korg Rhythm schematics, you can see that Korg has the BD DECAY and SD DECAY points at completely different places in their respective circuitry than the HH DECAY and SD NOISE DECAY points. Those two points (BD and SD) are rather misnamed - they really should be labelled BD GAIN and SD GAIN - because they're located at the spot for gain adjustment of their respective unbypassed CE amplifiers. This means that when you connect a resistor or cap to ground from those points, you're not changing that sound's 'decay' by adding capacitance or resistance - you're actually shifting the gain and/or frequency response of the transistor amplifier for that sound. So the circuit used for these two points must be different.

So here are some simple circuits to use pots with the drum mod points for a full range of control over their settings:

The DECAY circuits (HH / SD NOISE):

Parts (for each circuit):
1x 1N4148 diode
1x log. potentiometer - any size between 1k - 500k, as long as you have a fixed resistor that is 10x larger.
1x resistor - 10x the size of the pot you use; e.g. if you use a 10k pot, you need a 100k resistor.
1x resistor - for the shortest decay you want. If you want zero decay (no volume) at one end of the pot, ~47k should work.
1x capacitor - for the longest decay you want. Perhaps 10 - 100nF, but you can experiment by just holding the cap from the labelled point to GROUND while listening to the rhythm at the slowest possible tempo. Make sure to listen via headphones (or line out) when testing.

Explanation:
The potentiometer sets the bias for the connected diode, thus determining the time at which the timing capacitors will discharge through it - from immediately (no sound) to never (maximum decay). The 1st fixed resistor limits the maximum voltage at the pot wiper to the approx. drop of the diode - and the 2nd one limits the current during discharge.




The GAIN circuits (BD / SD FRAME):

Parts (for each circuit):
1x 25k linear potentiometer
1x capacitor - to set the bypassing (AC gain) of the respective amp. Perhaps 1uF - 220uF (I've been using 220uF for the BD, but I haven't experimented with SD FRAME yet), but you can experiment by just holding the cap from the labelled point to GROUND while listening to the rhythm. If you use a polarized cap, make sure the + side is to the labelled point. Make sure to listen via headphones (or line out) when testing.

Explanation:
The potentiometer forms a bypassed gain adjust for the respective amplifier. Turning the pot changes the amount of bypassing as well as the gain - from zero gain (no sound) to unbypassed gain (approximately the stock Korg sound - middle position) to completely-bypassed full gain (the sound with the added cap).




Please feel free to post any questions or comments.
GNSDG
Interesting. Thanks so much for such a thorough explanation.

Do you see the possibility to change the SD and BD more fundamentally, as in decay, tone, attack, etc?
CeeJay
Thank you marmad for posting your schematics and your very good detailed descriptions! I'm looking forward to give them a try. I'm not really happy with my existing drum mods.
marmad
GNSDG wrote:
Interesting. Thanks so much for such a thorough explanation.

Do you see the possibility to change the SD and BD more fundamentally, as in decay, tone, attack, etc?


Well, changing the AC gain does affect the tone by making different frequency components of the waveform more or less audible (and by possible distortion in the amp). Also, since you're changing the amplitude, the perceived lengths of attack and decay change too.

Of course, you could get into other parts of the circuitry to shape the pulse before amplification (as with the HH and SD NOISE) - but I was trying to present a mod that just uses the existing Korg-marked points. Also, these aren't very complicated waveforms - they are single-stage transistor-amplified R/C pulses; for example, the only difference in the pulse circuit between BD and SD is the value of 4 caps and 1 timing resistor.

Look at the following comparison images (the white reference waveform is always the stock BD OUT).

BD OUT compared to SD FRAME OUT:




BD OUT with GAIN increased by 330R to GND:




BD OUT with GAIN bypassed by 100n to GND:




BD OUT with GAIN bypassed by 220u to GND (using gain circuit from last post):




One other variation on the gain circuit from my last post that could be used to alter the tone of the drum more, is to increase the gain of the amp before bypassing - as in the following schematic. If you do that, you need to decrease the bypass cap to avoid oscillation (in my test, I lowered it from 220u to 10u).




The main drawback of this method is that the stock BD sound is not returned when the amp becomes unbypassed, but if you don't care about that it could be a better solution. You can see in the following images the results.

Gain circuit #1 (from last post) with pot in ~middle position (no bypassing) - and the waveform is almost equal to stock BD OUT:




Gain circuit #2 with increased gain before bypassing:




Gain circuit #2 with pot in ~middle position (no bypassing) - and the waveform is still quite different from stock BD OUT.

marmad
Here's a video look at what causes the severe clicking and popping in the Monotribe, as well as a couple of things you can do to eliminate them.



BTW, I'm designing an internally-mounted board for the Monotribe which will include the following features:

Click/pop noise suppression caps shown in this video
Individual drum decay/gain circuitry I posted about previously
Amplified outputs for HH, snare, BD, and full rhythm section
Trigger outputs for HH, snare, and BD
1V/Oct CV Out (+4V range) w/adjustable offset
Gate Out (not Sync)
EG to Rhythm volume
EG/VCO2 to VCA select
3 new inputs to the VCF:

1) VCO2 - with following controls
a) LFO/Normal Range
b) Triangle/Square output
c) VCO1 CV on/off with +4 octaves tracking
d) Coarse/Fine Tune
e) Hard/Soft VCO1 Sync w/intensity
f) Volume

2) Sub-oscillator - with following controls
a) VCO1/VCO2 input
b) -1/-2 Oct select
c) Volume

3) Pulse width modulator - with following controls
a) VCO1/VCO2 input
b) VCO1/VCO2/EG modulation input
c) Inital pulse width
d) Modulation intensity
e) Volume

There will also be boards for the mounting of the switches/pots/jacks along the top/sides - although the control board can be used with your own placement of pots, etc.

The boards are being designed for 4 Monotribes belonging to a client, but there will be spares - so I'll post info here when finished. Anyone interested can pick up a set of the spare boards for a reasonable price.
GNSDG
Oh my goodness--please please do let us know. I'll be first in line to pick one up.
mckenic
Fascinating video and yes please! I think you are going to need more than a couple of boards hihi

Dont know if my Tribe can fit any more in there (Daren's extra VCO & AM Midi) but I would certainly buy a 2nd Tribe just for this!!!

thumbs up
neilbaldwin
Sounds great. Looking forward to seeing this in the flesh. thumbs up
boxxgrooved
marmad wrote:

BTW, I'm designing an internally-mounted board for the Monotribe which will include the following features:
.


BTW??

That deserves a huge shout, not just a passing mention! That is a serious set of modifications, hats off!

And thanks a lot for showing us how we may eliminate it ourselves without much effort, greatly appreciated.

I was complaining about the 'clicking monotribe' in a recent thread but I may just have to pick up another one now.

Respect
marmad
Thanks everyone!

All the circuitry has been breadboarded and tested with the Monotribe plus another synth and is working fine - so I will also post a full set of schematics once the board design is finished for those that want to roll their own.
Kernelkunt
That sounds like an awesome mod. Do you have any sound demos yet?
marmad
Kernelkunt wrote:
That sounds like an awesome mod. Do you have any sound demos yet?


Unfortunately not - I didn't record any audio or video of it yet. But perhaps I can manage a short demo of some of it in the next couple of days; I'll see what I can do.
darenager
Nice work! I have not had a chance to explore the Monotribe since the schematics were posted, but one thing worth looking at reducing is the noise on the drum section when idle, probably a fairly simple fix.

One hacky way I was thinking was to interrupt the drum mix signal before the output, and have a little mute circuit that unmutes on play button, but it would not work for midi, so not ideal.
marmad
Kernelkunt wrote:
That sounds like an awesome mod. Do you have any sound demos yet?


Here's a short video demonstrating VCO2 control of VCA, VCO2 CV tracking, and soft/hard sync w/VCO1.

As mentioned in the video, I've pulled apart much of my breadboarding, but if there's something specific you'd like to see demo'ed, let me know and I'll see what I can do.

Suburban Bather
How much are the boards going to cost?
marmad
Suburban Bather wrote:
How much are the boards going to cost?


No idea yet - just started work on the design. It depends a bit on how many spares there are - and if they're sold partially populated or not.

The boards will be a mix of some SMD and some through-hole parts, so once they're finished, I'll try to get a consensus on whether people need to have the SMD parts mounted for them or not. If the boards are sold totally bare, I don't imagine it will be that much - I'm already making my money with the design and building for the client.
Suburban Bather
Board with the SMD parts mounted, please This is fun!
milkshake
Suburban Bather wrote:
Board with the SMD parts mounted, please This is fun!

This.

I just love the sound of that triangle, nothing sounds like that.

It would be cool if both vco's can crossmodulate each other.
marmad
BTW, for those interested in old synthesizers - you might consider subscribing to my YouTube channel.

In the next couple of months I'll be posting teardown and operational videos for some great old esoteric analogue/early-digital gear, including a Putney VCS3 used by Pink Floyd and an AHB Impulse One E-Drum Synthesizer - among other stuff.
grenert
Looking forward to the other videos. May I ask what your interesting dayjob is that you get to do this for a living?
Regarding your mod boards, I am OK with bare boards.
marmad
@grenert:
grenert wrote:
May I ask what your interesting dayjob is that you get to do this for a living?


Sorry I'm slow responding - I somehow missed your post notification.

But I'm not quite sure I understand your question - this IS my dayjob - or at least a portion of it. I do all kinds of different freelance electronic (or software) work - and this is one regularly recurring avenue.

From feedback, it sounds as if some people would like the SMD parts populated - and some are fine with bare boards - so I'll try to come up with a scheme to offer either.
dpowell
Wow...what a great thread...it inspired me to join the forum! I just picked up a monotribe this week (loving it!) and my head is spinning with all the mod possibilities. I'll probably start with Midi...

Has anyone used this USD Midi module?

http://www.altmustech.com/um-q110.html

Its significantly cheaper than the other options I've seen, and its probably this or DIY for me, unless there is something similarly priced, or a compelling reason to go another direction. It might be nice to have seperate midi IN and OUT though...


@marmad: I'm definitely interested in a board, in whatever form I can get it. Put me on the list!
zmb
Hey probably somebody covered this but the thread's gotten really long. is it safe to plug the headphone output into the audio in for extended use? I would think so, since it's presumably meant to take audio signals all day long, but maybe there's something I'm not aware of.
gooneybird
i need more practice before i open up my monotirbe or any thing for that matter... im kind of looking to mod my volca keys..it tends to shut off if too much is going on. maybe a better power supply would help??
bonso
zmb wrote:
Hey probably somebody covered this but the thread's gotten really long. is it safe to plug the headphone output into the audio in for extended use? I would think so, since it's presumably meant to take audio signals all day long, but maybe there's something I'm not aware of.


I've done this for about 2 years without an issue, so I think it's ok but I can't be certain on a technical level.

@marmad - Looks really great so far. Providing the boards don't require too much assembly, I'd be very interested in having one!
zmb
bonso wrote:
zmb wrote:
Hey probably somebody covered this but the thread's gotten really long. is it safe to plug the headphone output into the audio in for extended use? I would think so, since it's presumably meant to take audio signals all day long, but maybe there's something I'm not aware of.


I've done this for about 2 years without an issue, so I think it's ok but I can't be certain on a technical level.
Cool good to hear.
BARE BONES
would definitely be interested in a board with the SMD parts mounted love
dharmaone
One for the list too, would love another VCO and PWM on this. Do you have a website for this? need one - i can help?




dpowell wrote:
Wow...what a great thread...it inspired me to join the forum! I just picked up a monotribe this week (loving it!) and my head is spinning with all the mod possibilities. I'll probably start with Midi...

Has anyone used this USD Midi module?

http://www.altmustech.com/um-q110.html

Its significantly cheaper than the other options I've seen, and its probably this or DIY for me, unless there is something similarly priced, or a compelling reason to go another direction. It might be nice to have seperate midi IN and


DONT - ordered one this winter, never came, paypal didn't refund because i took over 45 days to file a complaint. Never got in touch with seller
darenager
I sell midi kits and other stuff for the Monotribe if you can't find one, many happy wigglers have bought them, probably not the cheapest but great quality, if interested check out my blog in my sig.
Kernelkunt
darenager wrote:
I sell midi kits and other stuff for the Monotribe if you can't find one, many happy wigglers have bought them, probably not the cheapest but great quality, if interested check out my blog in my sig.


I can vouch for daren, class act all the way.
e235
Please count me in for one of the boards too
what gives?
Greetings everyone! New here.

I am planning to mod my monotribe with a MIDI kit. My primary plan is to solder the midi mod wiring internally to the sync sockets (provided it's possible to disconnect the sockets from the sync circuits without removing the actual sockets). Plan B would be replacing the entire sync socket with new TRS ones, and attach them in the original casing holes.

If my plan will work, this way i should be able to install the mod without tampering with the casing by drilling holes, for instance. Therefore i wanted to check some things:

With my understanding the sync plugs/sockets has a TRRS configuration. I tried to find info on the configuration in this thread, but couldn't find it. Could someone tell how they're configured in detail?

Will I be able to directly solder the midi kit's wiring to the original sync sockets, or do I need to replace them with TRS sockets in order to function with midi TRS plugs?

I hope my plan/questions makes any sense. I'd really appreciate your opinions on this!
darenager
Whilst it would be possible to disconnect the sync sockets to repurpose them for MIDI sockets I can think of no reason why that would be useful, it is easy enough to drill the case, and by doing away with the sync function you are also losing CV/Gate and the sync, both of which can convert to MIDI data.

Just add some extra sockets.
what gives?
darenager wrote:
Whilst it would be possible to disconnect the sync sockets to repurpose them for MIDI sockets I can think of no reason why that would be useful, it is easy enough to drill the case

I'd rather avoid the drilling if possible.

darenager wrote:
and by doing away with the sync function you are also losing CV/Gate and the sync, both of which can convert to MIDI data.

For clarification, are you referring to externally (via cv/gate to midi gear) or internally (via the midi mod) converting here?

Resoldering the sync sockets back into place - if needed - should reverse the mod completely, wouldn't it?
darenager
What I mean is if you send CV/Gate(1) or analog clock(2) to the Monotribe it will send notes(1) or midi clock(2) from the MIDI out, so if you do away with the sync sockets you won't be able to do this.

The other thing to bear in mind is that if you slave the Monotribe to midi clock then stop the midi master but want to run the monotribe on its internal clock you will have to turn it off then on again, if you leave the sync sockets intact you can just plug then unplug the sync cable to re-activate internal clock.
what gives?
Now i get it! Thanks for your input.
snyder80
Hi there,

just want to propose my monotribe modifications.

De-Hum Drums LED:
since the Drums haven´t got a vca/Noisegate as the Synth part, there was a constand low hum depending on how many Sequencer-LEDs were on.
Quick look @ the thankfully posted schematic, there was no decoupling for the 3.3V DC LED-Matrix.
Solution: Simple enough, just cut the trace after C3 (lead run under the first row of switches) add a 330E SMT-resistor followed by 100uF 16V II 100n film cap. For the Ground-connection you can use the solder-pad from the non-mounted C1.

VCA de-click:
Fist i tried to use a small ceramic cap (15pF-56pF) between the collectors of the LTP (like used in valve amplification). This gave a slight HF-rolloff, but the did not help enough against "clicking".
I thoght about adding a BJT inline with the R202 like in VCA2 and VCA3 from "Schmitz Bits" (schmitzbits.de/vca.html).
But this was too much hassle.
As marmad already told, use a cap to ground from the base of Q24. I can not recommend using an electrolytic cap, since it takes time charging and discharging. I used a 1uF Wima foil cap. If you go bigger - like 10uF - you might get some HF glithing if you play fast on the keyboard an in the higher registers.

Aux-In:
Since the lug on the auxin wasn´t connected like in the Monotrons, i added in a simple and tiny BC847B as a switch in place of R120 with 10k from Base to Bias . Dont forget to connect a 15k smd between the emitter an the Waveform-switch-output. Collector goes to IC14A Pin2.

Midi:

I had a 6n138 and this did the awkward "midi-clicks". Since the solution with a 820E inline with Rx didnt feel right for digital signals i used a diode level converter like here: http://www.hobbytronics.co.uk/schottky-logic-level-conversion and http://jamesreubenknowles.com/level-shifting-stragety-experments-1741

Works like charm. Maybe later i will use hobbytronics´ Mosfet Logic-Level-Control or the usual 2stage sn74 inverter to buffer the Tx up to 5V.

Drums:
maybe they get a treatment later. I found some inspiration at www.wiesolator.de/index.php?area=Musik&topic=Monotron&stopic=Monotron- Trio
Only thing i dont like about the drums is the Volume of SDNoise. A big cap (470n up to 10uF) from SDNoise Out to Ground gave slightly more "body" to the SD. Maybe i would use a pot between the cap and ground, to change the amount of this LPF.

In the end i want to add those bending-point to an old 15pole gameport-jack, so i can use an external "Modbox".

cheers,

snyder80
darenager
Nice work! Any chance you could post some photos, especially the drum de-hum?

For the VCA de-click a multi-turn trimmer makes a big difference, I think I used a 26 turn one, and if care is taken the click can be drastically reduced by this alone. The standard trimmer is a little difficult to remove so I just snipped the legs and removed it like that.
snyder80
Hi Darenger,

so here is a comparison and some pics/sound from the LED-Noise-Fix.

I recorded a sample in Audacity (normalize - LPF @ ~300Hz to get rid of the hissing- normalize again) with the 100E and 100uF and 100n in parallel. The 100n cap in parallel with the 100uF is very important for the effective decoupling!

The drums Volume was "cranked", and Sequencer Steps 1-8 on, so the Leds were on, as well. Soundfile with 3 Samples: with 100E in - jumpered the 100E - LPF working again.

One advice: Dont go higher than 330E, because with 470E it drops abaout 1,2 VDC and this makes the leds dim and also adds some noise from the pulsating tempo. The Difference in Sound and DC-Drop with 100uF II 100n is

100E=15,9 Hz and 0.25 DC drop

220E=7,23 Hz and 0.5 DC drop

470=3,39 Hz and 1.2 DC drop

In theory you could use a 1.000 uF to dampen the Frequency to 1,59 Hz with 100E, but those caps would be much to big to fit in and i am not sure the IC1 could handle such an amount capacity. Higher than 100uF actually could fry the chip !

Greetings,
snyder80

EDIT: sound and pic added
Majonymus
well ive tried to mod the drums for the second time and cant figure it, im putting this in hold until i learn more confused

cacophonator stripboard time twisted
christianizm
anyone know how I can contact. site won't let me view profile
christianizm
Altitude909 christianizm@gmail.com
christianizm
Altitude909 wrote:
Haha Darren, we must think alike. Same 3.5mm jacks and everything razz


For ppl in the US/CA: Same Deal as Darenager

$25 USD, $6 US shipping, $12 CA. USPS just jacked international rates by 70% so US and Canada only




christianizm@gmail.com please contact me...
Altitude909
Sorry,

I haven't made those for a while, I think Daren made them as well..
zmb
snyder80 wrote:

VCA de-click:
Fist i tried to use a small ceramic cap (15pF-56pF) between the collectors of the LTP (like used in valve amplification). This gave a slight HF-rolloff, but the did not help enough against "clicking".
I thoght about adding a BJT inline with the R202 like in VCA2 and VCA3 from "Schmitz Bits" (schmitzbits.de/vca.html).
But this was too much hassle.
As marmad already told, use a cap to ground from the base of Q24. I can not recommend using an electrolytic cap, since it takes time charging and discharging. I used a 1uF Wima foil cap. If you go bigger - like 10uF - you might get some HF glithing if you play fast on the keyboard an in the higher registers.


Just did this simple fix using a 4.7uF electrolytic and it seems to work perfectly, I don't hear any clicks anymore which is great because it was one of the main reasons I haven't been using my monotribe recently. I haven't noticed any serious changes to the envelopes either, I think it's too fast to really hear a difference. Merry christmass
bobby68
Altitude909 wrote:
Sorry,

I haven't made those for a while, I think Daren made them as well..


I have your MIDI kit for my Monotribe, and I'm very satisfied.

But I just got another Monotribe, and need a TRRS cable for CV and Gate. I see severel headset splitter cables on EBay, like this http://m.ebay.com/itm/261661488153?nav=SEARCH

Do you know if this cable will work with the Monotribe?


Thanks.
Altitude909
bobby68 wrote:
Altitude909 wrote:
Sorry,

I haven't made those for a while, I think Daren made them as well..


I have your MIDI kit for my Monotribe, and I'm very satisfied.

But I just got another Monotribe, and need a TRRS cable for CV and Gate. I see severel headset splitter cables on EBay, like this http://m.ebay.com/itm/261661488153?nav=SEARCH

Do you know if this cable will work with the Monotribe?


Thanks.


wow, for that $ its worth trying..

I got my TRRS cable at sparkfun btw
bobby68
Altitude909 wrote:
bobby68 wrote:
Altitude909 wrote:
Sorry,

I haven't made those for a while, I think Daren made them as well..


I have your MIDI kit for my Monotribe, and I'm very satisfied.

But I just got another Monotribe, and need a TRRS cable for CV and Gate. I see severel headset splitter cables on EBay, like this http://m.ebay.com/itm/261661488153?nav=SEARCH

Do you know if this cable will work with the Monotribe?


Thanks.


wow, for that $ its worth trying..

I got my TRRS cable at sparkfun btw


I have now ordered one, and will post here if it works smile

Thanks.
darenager
I tried one similar to that and it did not work, worse is that it has that stupid wire that can't be re-soldered because it has some weird coating on it.
bobby68
darenager wrote:
I tried one similar to that and it did not work, worse is that it has that stupid wire that can't be re-soldered because it has some weird coating on it.


To bad :( Well it was atleast pretty cheap...
darenager
Well that might be different pin config to the one I used, the one I tried had ground on ring 2 IIRC.
stopthesignal
Hi all. I would really like to do do marmad's de-click mod on my 2 monotribes (2.2uF capacitor from base of Q24 to ground). With that said, I don't have very much experience with modding and I need a little bit of hand-holding. If anyone is willing, could you possibly provide the following guidance:

1. Specifically what kind of 2.2uF capacitor should I get? marmad didn't specify, but snyder80 suggested something other than electrolytic. If someone could provide a link to a good option, that would be awesome.

2. Looking at pictures of the PCB, I'm not entirely sure what the solder points are for the base of Q24 and for ground. Can someone point them out with a posted image? Someone posted this image earlier in the thread, but it looks like it might be a slightly different version of the mod.

3. If I wanted to make the mod defeatable with a switch, as marmad suggests in his video, what would that circuit look like?

Thanks in advance. My apologies for requesting such rudimentary help.
marmad
stopthesignal wrote:

1. Specifically what kind of 2.2uF capacitor should I get? marmad didn't specify, but snyder80 suggested something other than electrolytic. If someone could provide a link to a good option, that would be awesome.

I used tantalum caps in my video just because I had those on hand in many different values for testing, but it's not that critical (we are talking about a very inexpensive piece of gear, after all). But if you want much faster charge/discharge times, you can use something like the WIMA film/foil caps snyder80 suggests.

Quote:
2. Looking at pictures of the PCB, I'm not entirely sure what the solder points are for the base of Q24 and for ground. Can someone point them out with a posted image?

I'm currently travelling and not around my lab at the moment, so please forgive the fact that I have to reuse Squidfanny's image (just ignore the purple lines). The base of Q24 is connected to the base and collector of Q23, so any of the points I've marked with a red dot can be used as connection points for the positive side of the cap. There are many point to make a ground connection - I've marked a few with yellow dots.

Quote:
3. If I wanted to make the mod defeatable with a switch, as marmad suggests in his video, what would that circuit look like?

I've drawn the basic schematic below the image. Hope this all helps.

stopthesignal
marmad,

Thank you so much! That was all very clear. I'll probably be trying all of this in the next week or two. I really appreciate the help.
mckenic
Well I decided to get off my ass and try the de-click mod...

love

Just WOW!

As with the pic above - I just used a 10uF cap - negative to the Yellow in the pic below & positive to the red point. Did nothing else, cause MAN am I happy!



applause
stopthesignal
Just wanted to stop back in and say a big thanks to marmad. I did the de-click mod per his excellent instructions and it worked perfectly. I ended up using a 4.7uF electrolytic capacitor. The film capacitors I had were a little too big for me to deal with.

It sounds great! Thanks!
ablearcher
I keep coming back to the monotribe, seems to be one of those pieces of gear (like the sh-101) that's musicality and usefulness is more than the sum of it's specs.

Question though: do you guys experience volume drops when playing it through midi?

I put in someone's midi mod board years ago (I don't remember which) and I love it, it lets me use the monotribe as a looping phrase sequencer, but as I play in notes there is a significant volume drop, then when they are played back to me from the sequence they are at full volume. Has anyone experienced this or know how to fix it?

also there is talk of an expansion board with a 2nd dco in this thread, is that still in the works? or dropped for newer and shinier things?
zmb
ablearcher wrote:
I keep coming back to the monotribe, seems to be one of those pieces of gear (like the sh-101) that's musicality and usefulness is more than the sum of it's specs.

Question though: do you guys experience volume drops when playing it through midi?

I put in someone's midi mod board years ago (I don't remember which) and I love it, it lets me use the monotribe as a looping phrase sequencer, but as I play in notes there is a significant volume drop, then when they are played back to me from the sequence they are at full volume. Has anyone experienced this or know how to fix it?

Not sure if this would be related but when i play the monotribe through midi it responds to velocity so maybe you're playing the notes at low velocity? Caught me by surprise when i first tried playing it because i'm used to hearing just one volume out of the monotribe.
ablearcher
Hahaha, if it's just the midi not velocity I'm gonna feel like an idiot. Might be though, been using a cz-1000 as a midi controller, no idea what it spits out.
rarara
do you mean the midi mod allows you to record notes in the monotribe that you play via the controller keyboard?

hope so....i got a unit with midi already installed but due to a house move most of my stuff is still in boxes help
ablearcher
Quote:
do you mean the midi mod allows you to record notes in the monotribe that you play via the controller keyboard?


yup! it's one of my favorite things. I just leave it in record + play mode and jam out on a midi keyboard plugged into it and it's basically a phrase looper. Really useful for live electro where you have many more boxes than hands.
oden
SOLVED

Hi all,

I am building a MIDI mod for the Monotribe and i am a bit stuck here on how to connect the DIN connectors according to this gentleman´s schematic:

http://dantonewac.blogspot.se/2013/01/the-mighty-mini-monotribe-by-kor g-now.html

Somebody here willing to explain how the cables are connected to the DIN sockets?

Cheers.

// Oden

Edit: Found the answer on the same webpage, my blind
Scott Willingham
Another kudos to Marmad for publishing clear directions for the click/thump reduction mod. I modified mine about two years ago (2.2uF), got busy and lazy and never got around to sharing. d'oh!

I think it's a must-do, right after doing the MIDI-in mod. A bit of click on the attack of a sound can be considered "character" but clicking on the release is just annoying. Also, one of my favorite wiggling techniques on the Monotribe is to record a sequence and then play the ribbon with the gate-time button down. I love to interactively mute and choke the sequenced notes. Shame on Korg for not fixing this in the firmware.

Technical notes:

The software envelopes are created by pulse-width modulation (80kHz) filtered with a Sallen-Key filter. The stock minimum rise- and release- times are less than 100 us. With 2.2uF added, the minimum rise/fall times are about 2 to 3 ms.

The VCA circuit has an offset adjustment trimmer. I replaced all the critical resistors in my VCA with 0.5% types and tried to trim out the clicks/thumps. This partially works but is not reliable. The problem is that the filter is DC-coupled to the VCA (good for bass response) and that the DC output of the Korg-35 style filter varies with the filter settings. So too-fast envelopes cause audible steps in the VCA output.

EDIT 2015.03.25: For completeness, here's a photo of the click/thump mod in my MT:



I used a tantalum cap because that's what I had laying around. IMO, any capacitor type will work fine.
Scott Willingham
Holy crap! I can't believe I missed the schematic posted here almost a year ago. very frustrating Wish I had that two years ago when I traced-out half the circuit board for a couple of mods. Anyway, finding it now has inspired me to pull apart my Monotribe again and post a few observations and mods.

The first simple mod is muting the VCO when the audio-in jack is used. Several have posted mods to do this by adding a switch to ground-out the signal in various places, generally around the WAVE switch (SW7A). I recommend grounding pin 4, which comes from the square-wave circuit. Pin 1 (saw) also works, but disrupts the circuit balance a bit more. Pin 2 (tri-wave) or Pin3 (output) are not recommended since they can short the output of opamp IC13A.

A simple way to short the signal without drilling the MT case is to use the extra contact on the AUDIO-IN jack. This extra contact is open-circuit when no plug is inserted and grounded to the plug sleeve (ground) when a plug is inserted.



Connect a wire from this pad to SW7A pin 4 (sorry no picture). Now the VCO is muted when an audio jack is inserted and the WAVE switch is set to square. Other settings of the WAVE switch will keep the oscillator.

That said, this grounding of the oscillator waveform is a bit of a hack. It introduces a large DC offset to the signal chain. (Monotribe has a single supply, so internal signals are referenced to a bias of about 1.35V above ground.) The mute is effective, but the Korg-35 style filter will not be operating optimally. Still, it mutes, and you can play around with external signals, or just run the plain noise source through the VCF+VCA.

Cheers
Scott Willingham
In a previous post, snyder80 identified the cause of hum from the LED scanning circuits into the Rhythm circuits. He also posted an effective fix. I've been looking into this a bit further.

Indeed, the problem stems from the LED scanning circuit, which kicks noise back into the +5V supply. The LED sub-circuit has it's own 3.3V regulator, but regulators aren't really effective at preventing noise from kicking back into the original supply. Whatever current pulses are required by the LEDs, this current must flow through the regulator. Only various decoupling capacitors and series resistors help isolate the current pulses to a local loop.

Korg did generally the right thing here, with a series resistor, R1, and a large capacitor on the input side of the LED regulator. The RC combination smooths the local load-current pulses and more of a smooth "average" current flows back into the +5V supply. But Korg didn't do quite enough. R1 is only 22 ohms and drops about 250 mV on average. There is conservatively about another 1V headroom.

So a simple first fix is to just replace R1 with about 80 ohms, which will reduce the hum current 10-12 dB. This resistor could be a bit bigger, but I think it makes sense to accommodate LED variations from unit to unit. Generally, we want the input side of the LED regulator (IC1, pin 5) to stay above 3.5V. Listening to this, I found the hum substantially reduced to the point of being good enough for most purposes.

But we can do better, and in the process, improve other noise...

The other half of this issue is the "victim" circuits in the Rhythm section. In some places, these simple analog drum circuits have little to no power-supply rejection. After replacing R1, I found the remaining 125 and 250 Hz noise on the +5V supply was well under 1 mV. Generally, audio circuits should not have a problem with that.

After some investigation, it turns out that the LED hum is dominantly transmitted through the Snare Frame circuit. (Grounding the SD Frame Out patch point eliminates the hum.) The reason for this is because the snare circuit is a bandpass resonator near 250 Hz. The power-supply noise actually resonates through to the output.

So the second modification consists of putting a small filter on the snare frame supply (top of R56). I cut a small gap in the trace from +5V to R56 and bridged the gap by 500 ohms. Then I added 10 uF from the top of R56 to ground. This RC filter has a LP corner frequency of about 32 Hz. The resistance is low enough to barely affect the circuit bias point and there is about 12 mV extra droop added to the supply when the snare fires, compared to a signal amplitude over 1.5 Vpp.

And that kills the hum! cool

But there's more. In sussing out where the hum was entering the Rhythm section, I noticed that if I short the HH OUT patch point to ground, the hiss in the Rhythm section is greatly reduced. Looking at the schematic, it is easy to figure out why. When the HH is idle, the collector of Q8 pulls up to the +5V supply and the signal path is a high-pass filter to the output. All the hissy noise on the supply is added to the signal. eek!

This can be cured by letting the new RC filter do double duty, filtering the HH supply as well as the snare frame supply. Adds about 25 mV drop when the HH fires. No big deal as far as the desired signals. But slashes the hiss.



Now my Monotribe's Rhythm section idle noise at full volume is nearly as quiet as the synth. So quiet, that with tight headphones and a bit of concentration, I can just barely perceive a small 250 Hz hum again. hihi

Cheers
darenager
Nice additions to the mods Scott, I do my mute the same way and in practice it works ok. I think also that replacing the single turn trimmer with a multi-turn one makes a huge difference in trimming out the offset, it is a bit of a pain to replace but worth the effort.

My drum mutes short the various drum outs to ground using switches, and I noticed that the snare body and hi-hat do indeed contribute to the drum mix hum/hiss.

When I get the time I will try the drum hum/hiss reduction mods of yours and snyder80.
Scott Willingham
darenager wrote:
I think also that replacing the single turn trimmer with a multi-turn one makes a huge difference in trimming out the offset, it is a bit of a pain to replace but worth the effort.


Rather than a multi-turn, I replaced R94 with a 100kohm resistor (stock is 10k), reducing the sensitivity of the single-turn by 10x.

My observations were that I could trim away most of the thumping, but there was still noticeable clickiness. Also, the thump would come back when turning the VCF cutoff knob. This was a dynamic thing, turning the knob caused thumps that would fade away again. I concluded that this was due to varying DC offsets in signal chain. It is possible this varies from unit to unit, depending on your luck.
Scott Willingham
I have one more and it's my favorite, adding PWM to the Monotribe. I call it a "stealth mod" because I am too lazy to drill holes in my MT (except Midi-in), so I added this with no extra knobs or switches. Two PCB trace cuts, two resistors, and some wires -- so great bang for the buck. w00t

How does it work? Well the wonderful switches on the MT are 2-pole, 3-throw types, and only half of the WAVE switch is used. With this mod everything works normally when Saw or Tri waves are selected. When the Square wave is selected, the mod re-routes the LFO->VCO Pitch modulation, instead feeding the LFO into the pulse waveshaper. (Be sure to set the LFO TARGET switch to VCO or VCO+VCF.)

This is the circuit:



The switch shown is part of SW7, the WAVE selector. Note that the order of terminals in this drawing is not the same as in the photo below. The only elements added to the MT are resistors RA and RB and some wires. Their values are chosen to cover the full duty-cycle range when LFO INT is maxed, with a slight over-modulation (glitchy smile). When the LFO is in 1SHOT mode, the modulation covers 50 up to 100%. In FAST/SLOW modes the modulation range is 0 to 100%, balanced around 50%. You can customize the modulation max depth by adjusting RA and/or RB.

STEP 1 -- Cut the pulse wave threshold connection IC13 pin 9 from the global BIAS node:



STEP 2 -- Cut the VCO modulation connection between IC15 pin 7 and R14:

(This is where I did it, on the front side of the board. Many other locations can work.)



STEP 3 -- Add resistors and wire.

(I connected RB to a relatively thick vertical trace. The diamond mark in the photo shows an equivalent test-pad that you may prefer. I kept my wiring short and neat, but soldered to some small tricky pads. I've described the various connections to IC pins or resistors where you may find it easier to solder.)




One small quirk: when you switch the WAVE from SAW or TRI to SQUARE and the LFO modulation is rerouted, there is a small DC offset change that throws the VCO pitch off by a bit. Don't worry though. Just halt any sequence and don't touch the ribbon for 2-3 seconds. The Monotribe will internally re-tune the oscillator and you are back in business. Not ideal, but what can you expect from a two-resistor mod?

I think that's it. Hope some of you will try this out. I can assure you that the sound is Rockin' Banana!
Scott Willingham
Scott Willingham wrote:
darenager wrote:
I think also that replacing the single turn trimmer with a multi-turn one makes a huge difference in trimming out the offset, it is a bit of a pain to replace but worth the effort.


Rather than a multi-turn, I replaced R94 with a 100kohm resistor (stock is 10k), reducing the sensitivity of the single-turn by 10x.

My observations were ...


Ack! I thought I was done. But listening again to my MT, the VCA still seemed too thumpy. So I pulled it all apart again. sad banana

In the end I made one more improvement, but even better, I learned something new and solved a Monotribe mystery that's been bugging me.

At first I tried to re-adjust the VCA trimmer. Finding the balance too sensitive, I took Daren's advice and substituted a multi-turn pot. Even so, there was a modest reduction of DC thumping, but no real sweet-spot. I began to wonder if there is some other problem besides the DC balance, maybe affecting some Monotribes more than others.

Doing a little research, I studied Rene Schmitz's very similar VCA-3 (VCA link) and noticed that in addition to an "offset" trim, there is also a "CV rejection" trim. The last time I thought about this, I concluded that just one trimmer was sufficient. But I neglected to think about the more subtle differences between offset in the signal path and common-mode rejection of the CV signal. Each requires its own trim. Trimming one path does not fully compensate the other.

I added a new trimmer, multi-turn 500 kohms. Pins 1 & 3 wired to the bottoms of R219 & R220. The center tap wired to +5V. This trimmer enabled me to trim the VCA for near perfect CV rejection. (Procedure: short-circuit the two base terminals of Q17 and set the sequencer for one step with 30% gate length. Listen to the output on headphones and adjust for minimal signal. It helps to look at the output on a 'scope too, mainly because at low levels, it is easier to see which direction to turn the trimmer. Then remove the short-circuit on Q17!)

After the CV trim, the normal DC trimmer worked much better for me. (Perhaps some MTs are built with better CV balance, which could explain why some owners report fewer click/thump issues than others.) The DC trim is still delicate and not totally perfect, but really good. I tuned mine again with a single-step sequence, 30% gate length. Sawtooth, note C at 16', EG type "flat", no LFO modulation, VCF set for zero peak and just open the VCF a bit on the fundamental. Adjust the DC trimmer for minimum thumping on the gate rise/fall times. Now, I like the results. There are still slightly audible artifacts at low VCF cutoffs, but with good character. And at wider filter settings, it sounds very clean.

Here's where I discovered something new (to me, at least). I've mentioned in previous posts that the DC level coming out of the filter seems unstable -- very slowly moving around. At low filter cutoffs, non-legato sequences on the Monotribe have an interesting "breathing" quality. Thumps and sounds that slowly come and go. Turn up the filter peak and the filter will slowly alternate between silence and pinging. Cool for meditative drones and such. But this behavior stumped me when trying to trim out those thumps. What slow process could cause this weird drifting? Was it thermal?

Finally, I looked at the filter output on my oscilloscope, then the VCO output. Aha! The VCO is doing something weird between gates, with varying frequencies. Sometimes the frequency comes through the filter, sometimes it is blocked. This causes the DC level in the filter to vary (the Korg-35 filter is non-linear).

Why is the VCO varying? It's the Monotribe's auto-tuning algorithm, snatching time in-between the notes to touch-up the VCO tracking. The VCO is switched over several octaves in the background. This causes the DC wander and associated "breathing" effect. Also, note attacks are subtly affected, giving a little more character to the sequence. cool

Another side effect: if you put some space in your sequences (not all constant 100% gated notes), the Monotribe will be able to keep pitch better by using those spaces to touch-up the VCO tracking.
darenager
I wondered if at low VCF cutoff frequency if perhaps some of the thumps were a result of filter tracking?

Talking of drones, another mod that I thought of was to remove R202 and add a DPDT switch and a thru hole 3.3k resistor, so that one side of the switch is connected to 5v, the other side to where R202 was, and the common terminal of the switch thru the new 3.3k to the junction of the base of q23/q24, so that you have choice of switching between EG controlling VCA or constant drone.

Anyway, thanks again for your findings Scott thumbs up
Scott Willingham
darenager wrote:
I wondered if at low VCF cutoff frequency if perhaps some of the thumps were a result of filter tracking?


With a normal sequence, that probably occurs (and is probably desireable), but I was using a single active step. One of the things I looked at was the filter control voltage and it was steady. Looking at the waveforms, however, it is clear that the VCO is jumping to different tones between gates, perhaps even subsonic.

darenager wrote:

Talking of drones, another mod that I thought of was to remove R202 and add a DPDT switch and a thru hole 3.3k resistor, so that one side of the switch is connected to 5v, the other side to where R202 was, and the common terminal of the switch thru the new 3.3k to the junction of the base of q23/q24, so that you have choice of switching between EG controlling VCA or constant drone.


The VCA envelope does not go up to +5V, so you would need a resistor pull-up to set the right voltage/current. From previous measurements, I saw that the max envelope voltage depended on the envelope shape. About 2.0 V for the soft-attack mode, 1.3 V for the gate mode, and 3.3 V for the decaying mode (although it quickly decays to 2.4V in 32ms and then drops more slowly).

Unfortunately, I don't think the suggested mod will do what you want. As soon as the Monotribe's MCU "thinks" that the VCA is closed, it can start messing with the VCO for autotune.
darenager
Ah, yes of course, I forgot about the background autotune routine d'oh!

At present for drones I just set the envelope to the middle position and use the sequencer to do it so it was not a huge need to have the mod, I suppose as well it could be achieved using a constant voltage source into the gate input.
Altitude909
good God, this thread has me looking at my monotribe like a cannibal looking at Rosie O'Donnel
Spaker
Hello. I just posted my "Hi, I'm new here" intro message in the obligatory Meet the New Guy thread, but this thread is why I am here. I ran across this thread one night last week and read about 17 pages of it before I started to go crosseyed.

I've since been in contact with darenager and he's convinced me that I can do the MIDI mods I want to do for my Korg Volca family. Just want to put MIDI out on them, simple. But my Monotron.... I don't even know what to say. You guys have turned this thing into the F'ing SPACE SHUTTLE. The pictures on this page alone have my head spinning.

And I am no stranger to circuit building, schematics, soldering, wiring, creating from scratch or making quick repairs on audio gear. I build my own amps and high end speakers. I recently took up performing live again after a LOOONG hiatus in which I got married, had kids and became another boring suburban white dude. Instead of records, instead of doing what I used to do- mix tracks made by other people, I build my own, ground up in Ableton Live with a host of controllers.

And now I am trying to get my favorite Korgs in the Mix.

So, pardon the new guy, but I have a couple questions that searching this thread didn't help with. Maybe I wasn't entering the right search terms. And I have read all 34 pages once. I can't do it again. So two questions.

-Where is that link to the good MIDI female DIN socket you guys prefer? I've just never bought one and on mouser, the prices and "styles" are all over the board. I'm going to drill, not let wires hang out the battery door, so if there's one with it's "guts" mainly on the exterior that you have found, all the better. I saw a picture of one like that:





-What's the consensus on Monotribe MIDI IN / OUT as far as just doing that? I see there's click and pop issues. A picture on this page shows a ceramic capacitor placed strategically to prevent this. If I am going to do it, I am going to do it right. And then once I do have it right, what's the most useful mod you, as a team have generated for the Monotribe? Is it the drum separation mods? Turning off (down?) the VCO? I've got myself turned around there are so many, so many that are similar, but not the same.... and like I said, I usually start from scratch with a schematic, and not dive into a mass produced PCB that seems ripe for tinkering. I just haven't done it. I know I can... just have to dive in.

BUT First thing's first! I can't find the right DIN. I swear it was on mouser and I swear it was like 60 cents.... but I can't find it for the life of me. And modding my four Volcas with MIDI outs will warm me up for the big game- the Monotribe.

So- HI EVERYBODY! I'll be reading. I'll probably ask a stupid question or two. But we all know stuff other people don't. Like.... I worked in professional aerial pyrotechnics (that's FIREWORKS) for 18 years. I bet I know more about that than you. So help me out and I apologize now if I look dumb now and again. I'll get there. I always do.

Nice to greet ya,

Spaker
stopthesignal
Spaker wrote:
-What's the consensus on Monotribe MIDI IN / OUT as far as just doing that? I see there's click and pop issues. A picture on this page shows a ceramic capacitor placed strategically to prevent this. If I am going to do it, I am going to do it right. And then once I do have it right, what's the most useful mod you, as a team have generated for the Monotribe? Is it the drum separation mods? Turning off (down?) the VCO? I've got myself turned around there are so many, so many that are similar, but not the same.... and like I said, I usually start from scratch with a schematic, and not dive into a mass produced PCB that seems ripe for tinkering. I just haven't done it. I know I can... just have to dive in.

For adding MIDI To the Monotribe, I strongly recommend Altitude909's Monotribe MIDI kit, which he sells on ebay. Just look up "Korg Monotribe MIDI" on ebay. It comes with excellent instructions and is very straightforward. I installed it in one of my Monotribe's recently when I had it open to do the de-click mod and it was a cinch. On that note, if you do MIDI In/Out, you should do the simple de-click mod at the same time. Marmad provided excellent instructions for that in a post on one of the last few pages. Good luck!
zmb
Spaker wrote:
Hello. I just posted my "Hi, I'm new here" intro message in the obligatory Meet the New Guy thread, but this thread is why I am here. I ran across this thread one night last week and read about 17 pages of it before I started to go crosseyed.

I've since been in contact with darenager and he's convinced me that I can do the MIDI mods I want to do for my Korg Volca family. Just want to put MIDI out on them, simple. But my Monotron.... I don't even know what to say. You guys have turned this thing into the F'ing SPACE SHUTTLE. The pictures on this page alone have my head spinning.

And I am no stranger to circuit building, schematics, soldering, wiring, creating from scratch or making quick repairs on audio gear. I build my own amps and high end speakers. I recently took up performing live again after a LOOONG hiatus in which I got married, had kids and became another boring suburban white dude. Instead of records, instead of doing what I used to do- mix tracks made by other people, I build my own, ground up in Ableton Live with a host of controllers.

And now I am trying to get my favorite Korgs in the Mix.

So, pardon the new guy, but I have a couple questions that searching this thread didn't help with. Maybe I wasn't entering the right search terms. And I have read all 34 pages once. I can't do it again. So two questions.

-Where is that link to the good MIDI female DIN socket you guys prefer? I've just never bought one and on mouser, the prices and "styles" are all over the board. I'm going to drill, not let wires hang out the battery door, so if there's one with it's "guts" mainly on the exterior that you have found, all the better. I saw a picture of one like that:





-What's the consensus on Monotribe MIDI IN / OUT as far as just doing that? I see there's click and pop issues. A picture on this page shows a ceramic capacitor placed strategically to prevent this. If I am going to do it, I am going to do it right. And then once I do have it right, what's the most useful mod you, as a team have generated for the Monotribe? Is it the drum separation mods? Turning off (down?) the VCO? I've got myself turned around there are so many, so many that are similar, but not the same.... and like I said, I usually start from scratch with a schematic, and not dive into a mass produced PCB that seems ripe for tinkering. I just haven't done it. I know I can... just have to dive in.

BUT First thing's first! I can't find the right DIN. I swear it was on mouser and I swear it was like 60 cents.... but I can't find it for the life of me. And modding my four Volcas with MIDI outs will warm me up for the big game- the Monotribe.

So- HI EVERYBODY! I'll be reading. I'll probably ask a stupid question or two. But we all know stuff other people don't. Like.... I worked in professional aerial pyrotechnics (that's FIREWORKS) for 18 years. I bet I know more about that than you. So help me out and I apologize now if I look dumb now and again. I'll get there. I always do.

Nice to greet ya,

Spaker


Hey here's the midi socket on jameco, I couldn't find it on mouser either...
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_15 844_-1

Other than MIDI in, I found removing the envelope clicks was a real game changer. I didn't really hear anything until people started point it out in this thread, but then once I started hearing it, it drove me nuts. The mod was pretty simple and fixed the problem to my satisfaction though.
Scott Willingham
stopthesignal wrote:
On that note, if you do MIDI In/Out, you should do the simple de-click mod at the same time.


I heartily agree. Once you have MIDI-in, and play any non-legato notes, the clicks and pops become very noticeable. The simple addition of a 2 to 5 uF capacitor cleans up the sound a lot.

After those two mods, the rest is really a matter of taste. I've added advanced click/pop mods and a PWM mod. After that, I contemplate Daren's drum mods-- simple but nice variety. But if I need extra outputs or sounds, I will just go with my Volca Beats.

Wish we could hack the firmware...
Spaker
Well thanks guys. I have some options now. I was asking one of the kings of this topic over email about the DIN socket and he pointed me to one on his side of the Atlantic, but via the web, and it turns out by a place with tentacles reaching the globe. Element14 is how I first knew them, but I guess they have lots of subsidiaries or franchises or some kinda hogwash that made it simple to find the part he suggested here in the Colonies.

Since I am no stranger to the soldering gun, schematics, wiring diagrams and voluntarily tearing perfectly good electronics apart- I'm gonna attack my family of four Korg Volca's and outfit them with MIDI outs ASAP.

The Monotribe, what led me to you band of gypsies... I am undecided on. Like I told darenager in an email, I was barely touching the thing for a LONG while before I ran across this thread, then some YouTube videos. When I picked it back up, it seemed new again. It still seems new again.

I know I want to do the MIDI in/out thing for the Monotribe, and of course I will attempt to "stop the pop" by strategically adding a ceramic cap, per you guys. But I want to see and hear more of the other mods. I research things to death. And luckily, you guys are exhuming this Monotribe corpse again and again! And you guys are all CSI like, finding new stuff every time.

So thanks. I appreciate it. I'll be around.
darenager
Just a heads up for any of you guys thinking of buying one of my VCO mods for the Monotribe, the very last few left now:

http://monotribemods.blogspot.co.uk/2015/04/roll-call-last-ever-vco-mo d-run-5.html

Come fully assembled, just 4 wires to solder and some holes to drill using the provided drill template sticker, come with illustrated instructions sent by email.
rarara
there is a really nice sounding 'hard square' mod here: http://www.mrspring.info/vbulletin/showthread.php?2631-MOD-Korg-Monotr ibe-Modification

I can't view the diagrams yet, so can anyone explain exactly what is required from the description:

"hard square - used to reset the square wave - 2.2uf cap -/stripe/minus to pin 2 & + to pin 1 (looking front to back)
of the back of the waveform select switch - see the 3-wire ribbon in the pics? thats the waveselect switch.
There are some lovely waveshape distortions available from shorting out the various waves or mixing them, this
one caught my ear as it's actually a lot more square then the so-called square on-board. i guess they made the one
on-board a little fuzzy to give it some balls.. me though, i like a nice hard square."

i get adding the cap but should this be linked to a on/off switch?
grenert
Scott Willingham thank you very much for sharing the PWM mod! I hate case work, so always happy to avoid drilling holes. The mod sounds great! applause
Scott Willingham
grenert wrote:
Scott Willingham thank you very much for sharing the PWM mod! I hate case work, so always happy to avoid drilling holes. The mod sounds great! applause


Great! I'm happy to hear that it worked for you. I love PWM hihi

I'm pretty lazy about case-mods too, but I recently added Daren's drum mod kit and it was a breeze.
rarara
Scott Willingham wrote:
grenert wrote:
Scott Willingham thank you very much for sharing the PWM mod! I hate case work, so always happy to avoid drilling holes. The mod sounds great! applause


Great! I'm happy to hear that it worked for you. I love PWM hihi

I'm pretty lazy about case-mods too, but I recently added Daren's drum mod kit and it was a breeze.


Scott - am now considering the PWM mod (is there a soundclip anywhere??), but do you know how compatible it is with:

a) the synth mute mod where the waveform selector is grounded
b) the 'hard square' mod mentioned above.

I suspect the mute mod makes no difference, but was thinking of doing the other too.
Scott Willingham
rarara wrote:
Scott - am now considering the PWM mod (is there a soundclip anywhere??), but do you know how compatible it is with:

a) the synth mute mod where the waveform selector is grounded
b) the 'hard square' mod mentioned above.

I suspect the mute mod makes no difference, but was thinking of doing the other too.

Sorry, no sound clips. I play with synths, but rarely record. confused

For muting, I recommend shorting Pin 4 of the wave selector switch to ground (the square-wave). This doesn't interfere with the PWM mod. Note that you have to select the square wave to do muting in this case. I don't recommend muting on the output side of the switch, mainly because when a Tri wave is selected, you will short an opamp output to ground.

I took a look at that 'hard square' mod and listened to the demo (which sounds effective). The description is not completely clear, but it sounds like you just wire a capacitor and switch between pins 1 & 2. But I'm having a hard time visualizing how this works to improve the waveform's duty cycle. hmmm..... This mod shouldn't interfere with the PWM mod as long as the switch is open.
rarara
Scott Willingham wrote:
rarara wrote:
Scott - am now considering the PWM mod (is there a soundclip anywhere??), but do you know how compatible it is with:

a) the synth mute mod where the waveform selector is grounded
b) the 'hard square' mod mentioned above.

I suspect the mute mod makes no difference, but was thinking of doing the other too.

Sorry, no sound clips. I play with synths, but rarely record. confused

For muting, I recommend shorting Pin 4 of the wave selector switch to ground (the square-wave). This doesn't interfere with the PWM mod. Note that you have to select the square wave to do muting in this case. I don't recommend muting on the output side of the switch, mainly because when a Tri wave is selected, you will short an opamp output to ground.

I took a look at that 'hard square' mod and listened to the demo (which sounds effective). The description is not completely clear, but it sounds like you just wire a capacitor and switch between pins 1 & 2. But I'm having a hard time visualizing how this works to improve the waveform's duty cycle. hmmm..... This mod shouldn't interfere with the PWM mod as long as the switch is open.

what is the pin orientation in your photo? does it run

1 4
2 5
3 6

so you have 5+6 shorted? or are they 2+3?
Scott Willingham
rarara wrote:
what is the pin orientation in your photo? does it run

1 4
2 5
3 6

so you have 5+6 shorted? or are they 2+3?


I think the orientation is

4 5
Gap
3 6
2 7
1 8

Kinda weird, but that's how it relates to the Monotribe schematic. Pins 3 and 6 are the common pins. Pins 7 and 8 are the ones I shorted. They get connected to pin 6 in the Tri and Saw selections. Pin 5 is shorted to pin 6 when Square is selected.

Hope that helps!
rarara
janmaat wrote:
I've managed to make a simple line out for the drums. I you open the 'tribe, you can spot where the pot for drums volume is soldered onto the PCB: two big blobs and three small ones. I soldered the left of the three small ones to tip of a jack out, and jack out shaft to ground. Result is a (mixed) drum out independent of the pot. The pot still functions as before blending the drum mix into the complete mix for the mt line out. I guess if you solder to the middle of the three legs, your drum volume would influence the drum line out, but that's theory since I'm happy with my steady drum out.

anyone care to expand on this? I have tried and no joy - trying to test by feeding the new drum out into the audio-in to filter drums. and all that i can determine happens is that if i have the drum volume pot half way then plug earphones into the new seperate jack, it cuts the sound of the drums from the main out (?) and nothing comes out of the new jack either.
Scott Willingham
rarara wrote:
janmaat wrote:
I've managed to make a simple line out for the drums. I you open the 'tribe, you can spot where the pot for drums volume is soldered onto the PCB: two big blobs and three small ones. I soldered the left of the three small ones to tip of a jack out, and jack out shaft to ground

anyone care to expand on this? I have tried and no joy - trying to test by feeding the new drum out into the audio-in to filter drums. and all that i can determine happens is that if i have the drum volume pot half way then plug earphones into the new seperate jack, it cuts the sound of the drums from the main out (?) and nothing comes out of the new jack either.


Are you plugging the earphones directly into the new "drum out" jack? The suggested mod is unbuffered, so it has a fairly high output impedance. Thus it can drive something like a line-input to a mixer. Earphones, especially earbuds, have a very low impedance (like speakers). The drum-out mod cannot drive this load very well. Since you are tapping into the main signal chain inside the Monotribe, this also cuts the volume of the drums in the main mix.

Try feeding the new output into a mixer or computer audio interface to see if you get a drum signal.
rarara
argh, that's a pain - I want to feed the new drum jack directly into the audio in so will now have to find a more suitable mod very frustrating

what is the level expected with the audio in btw? as a quick test of an iPod signal didn't seem to work either
Scott Willingham
rarara wrote:
what is the level expected with the audio in btw? as a quick test of an iPod signal didn't seem to work either


Are you triggering the Monotribe? The external input does not automatically pass through the VCA without a gate. Try pressing the ribbon or running a sequence while you feed in the iPod.

(The VCO will sound as well. Hence the popularity of mute mods...)
rarara
yes, got a pattern running and the wave to ground to mute the synth. will try again with another cable.

any idea about a drum to vcf mod? have seen a video but nothing with any detail on how it is achieved
rarara
well the input seems fine when i don't by mistake use the volca bass sync cable instead of an audio cable d'oh! (which incidentally sounds good fed through the monotribe filter).

will try that drum out again now, just need to resolder a wire first
rarara
rarara wrote:
janmaat wrote:
I've managed to make a simple line out for the drums. I you open the 'tribe, you can spot where the pot for drums volume is soldered onto the PCB: two big blobs and three small ones. I soldered the left of the three small ones to tip of a jack out, and jack out shaft to ground. Result is a (mixed) drum out independent of the pot. The pot still functions as before blending the drum mix into the complete mix for the mt line out. I guess if you solder to the middle of the three legs, your drum volume would influence the drum line out, but that's theory since I'm happy with my steady drum out.

anyone care to expand on this? I have tried and no joy - trying to test by feeding the new drum out into the audio-in to filter drums. and all that i can determine happens is that if i have the drum volume pot half way then plug earphones into the new seperate jack, it cuts the sound of the drums from the main out (?) and nothing comes out of the new jack either.

OK, after using the correct cable oops I can confirm that this works fine. The level of the drums going into the filter isn't as high as the drums can be normally, but pretty workable (and could go via my mixer first i guess for a bump). Its also then possible to use the rhythm volume knob to have both normal drum sounds as well as the filtered version.

Now to do the drum decay etc mods...
Pase
Hi, are there any wigglers (maybe based in Italy or EU) that offer a professional modification service? I ask 'cause I've just bought an used unit and I'd like to transform it in a little monster, but I'm not able to do it by myself. Send me a pm if you're interested, thanks! wink
hamildad
Hi Pase,

I cant help you on the Monotribe, but I've just came back from a holiday in Sestri Levante, what a lovely area of Italy that is. we were in Zoagli, but took the train to Sestri most days to relax...

Seemed like there are a few interesting things happening in that area as well..

good luck finding someone to mod the tribe, I've added midi to mine, but not done anything further.
Pase
hamildad wrote:
Hi Pase,

I cant help you on the Monotribe, but I've just came back from a holiday in Sestri Levante, what a lovely area of Italy that is. we were in Zoagli, but took the train to Sestri most days to relax....

Glad to hear this, I hope you had good time here in Liguria wink
PolarAC
Hello. I’ve ran into an issue after I’ve done my mods. I was wondering if anybody had some advice.

For some reason, the synth volume level is now quite low on my MT. I’ve done the midi, drum decay, & de-click mods on my machine. Before the mods, the synth & rhythm levels were nearly equal at max (with the synth having the edge). After the mods, I’ve only been able to use the MT as a drum machine since the synth level has been nerfed so bad.

Anybody know where the issue may lie. If not, is there a synth/vca level mod that can increase the volume?
Scott Willingham
PolarAC wrote:
For some reason, the synth volume level is now quite low on my MT. I’ve done the midi, drum decay, & de-click mods on my machine. Before the mods, the synth & rhythm levels were nearly equal at max (with the synth having the edge). After the mods, I’ve only been able to use the MT as a drum machine since the synth level has been nerfed so bad.


I would suspect your de-click mod. Perhaps the capacitor you added is way too big, or it is damaged and very leaky.
PolarAC
Scott Willingham wrote:
PolarAC wrote:
For some reason, the synth volume level is now quite low on my MT. I’ve done the midi, drum decay, & de-click mods on my machine. Before the mods, the synth & rhythm levels were nearly equal at max (with the synth having the edge). After the mods, I’ve only been able to use the MT as a drum machine since the synth level has been nerfed so bad.


I would suspect your de-click mod. Perhaps the capacitor you added is way too big, or it is damaged and very leaky.


I see. I'll go ahead and replace it with a new smaller cap. Hopefully that will get it back to normal. Thanks
mckenic
Before you replace the cap - remove the old one and check if everything is back to normal (click included of course)...
rotallicso
Just wanted to say that I read the last 10-20% of this thread like a kid at christmas time (Thanks Scott!) - the years of procrastinating have paid off in that there is a smorgasbord of mods to chose from - as much as I'm an admirer of Daren's epic 'factory' builds I'm mostly interested in doing my own (that's 90% of the fun for me anyway - ps, same applies to sound-design, but Daren's druma patches for A4 are sublime) - a little bit of the procrastination was to do with procuring the right components at the time, but I'm set on using the spare 2.5mm>midi cables that came with the Line6 midi mobilizer, so it should be very easy to accommodate those (do it very cheaply without the stepped drill bit too) and leave room for misc trimmers, jacks and switches - i'd like all mods to be selectable (yeah, even the click ... part of the charm)
.
wondering if those with an experienced eye who've gone on this trip (and now with the benefit of hindsight) would care to propose their top five (solutions* from many above) in terms of simplicity/efficacy ? ... midi is a given, I guess I'm saying that it is a crazy long thread and there are competing strategies for similar ends, I can't use prior knowledge to 'know' what sounds the best approach - i'd like to give variation to the kick and anything to snare/hat would be a bonus - trig out(s) - separate the rhythm voice - de-click - not so bothered about extensive synthvoice tinkering (already great), but easy defeatable ones are a possibility - one main aspect that's a bit of a pity (probably for very good reason) is the user choice between cv in and sync in ... I'm guessing this is all locked in firmware and not something that can be hacked to work electronically
- a big pluspoint mod would be a good clean way to internally increase overall gain (even fixed) for integration with other gear expecting hotter output directly
.
sorry, bit of a meandering non-question, just wiping my feet I s'pose before I come in with detailed questions
is there a mac/web based electronics design tool that anyone would recommend for circuit design 'modelling' ? this tinkering is part of a baby step towards making e.g. a more modular centric hackfest within perhaps an ms20mini .... all that free space and panel room : ) ... there must be a mod thread for that somewhere, the ones I have seen are really unambitious and tame compared to what's panned out here already
.
thoughts/pointers welcome (even re uk based component suppliers or tools/sw of the trade to make life easier (on the cheap) besides voltmeter) -particularly keen to source those subtle 3.5mm mono jacks used by a909 and daren - particularly for a potential ms20 modspree (or links to more ambitious ms mod blogs)
.
anyway - thanks to all for sharing above, great stuff, inspiring !
mckenic
Without a doubt, even before midi, before anything else - the simple de-click! It is essential imho!
rotallicso
... Indeed, but which is *the* simple one, the least contestable ; ) this was my thrust ...
mckenic
Scott Willingham wrote:
Another kudos to Marmad for publishing clear directions for the click/thump reduction mod. I modified mine about two years ago (2.2uF), got busy and lazy and never got around to sharing. d'oh!

I think it's a must-do, right after doing the MIDI-in mod. A bit of click on the attack of a sound can be considered "character" but clicking on the release is just annoying. Also, one of my favorite wiggling techniques on the Monotribe is to record a sequence and then play the ribbon with the gate-time button down. I love to interactively mute and choke the sequenced notes. Shame on Korg for not fixing this in the firmware.

Technical notes:

The software envelopes are created by pulse-width modulation (80kHz) filtered with a Sallen-Key filter. The stock minimum rise- and release- times are less than 100 us. With 2.2uF added, the minimum rise/fall times are about 2 to 3 ms.

The VCA circuit has an offset adjustment trimmer. I replaced all the critical resistors in my VCA with 0.5% types and tried to trim out the clicks/thumps. This partially works but is not reliable. The problem is that the filter is DC-coupled to the VCA (good for bass response) and that the DC output of the Korg-35 style filter varies with the filter settings. So too-fast envelopes cause audible steps in the VCA output.

EDIT 2015.03.25: For completeness, here's a photo of the click/thump mod in my MT:



I used a tantalum cap because that's what I had laying around. IMO, any capacitor type will work fine.


mckenic wrote:
Well I decided to get off my ass and try the de-click mod...

love

Just WOW!

As with the pic above - I just used a 10uF cap - negative to the Yellow in the pic below & positive to the red point. Did nothing else, cause MAN am I happy!



applause


Two solder points to total bliss!!!
thumbs up
grenert
De-click is essential, IMO. I found mine difficult to listen to with the clicking. I think I used 2.2uF on mine. You could play around with different values to see what works best for you. MIDI of course because it is so easy and useful.

The only other ones I did were the PWM mod (excellent! really changes the character of the sound) and adding a switch to remove the oscillator from the circuit. I actually switched the oscillator out, rather than shorted it to ground.

I thought I was going to do some drum sound mods, but in the end, I like them quite a bit as they are. Not worth the hassle of soldering and drilling to me.
rotallicso
thanks, seems like there's a few safe bets, once I've whet my appetite with the definites i'll revisit the whole thread for guidance/inspiration
Pase
Sorry for the crossposting from the microgranny thread, but maybe here I'll get an answer to my midi noob question:
Does anyone knows if I can midi sync a Microgranny with a midi modded monotribe as master?
If I'm correct the monotribe convert the sync input in midi clock output, so if I have a first monotribe that send sync to a second monotribe, does it send midi clock to the microgranny?
Samaepstein
Pase wrote:
Sorry for the crossposting from the microgranny thread, but maybe here I'll get an answer to my midi noob question:
Does anyone knows if I can midi sync a Microgranny with a midi modded monotribe as master?
If I'm correct the monotribe convert the sync input in midi clock output, so if I have a first monotribe that send sync to a second monotribe, does it send midi clock to the microgranny?


Yes!
Pase
Great! Thanks Guinness ftw!
Pase
And here's my monotribe It's motherfucking bacon yo :

-midi in/out
-drum mix out (audio)
-individual mute switches for drum sounds
-individual drum decay/pitch switches
-declick
-pwm mod
SlayerBadger!
It's been modded for me by a great guy here in Italy ('cause sadly I'm not a diy guy oops )
Now this little groovebox rocks more than ever! Rawk! Champagne The Chewbacca Defense Animal!
rarara
Very neat job. Need to finish my mods, but been a bit distracted unfortunately.

Any idea what drum-out schema was used? And how are you liking the PWM?

Also need to do a FM modulation and distortion mod for my Volca Bass w00t
Pase
@rarara
Sorry but I really don't know which schema it's been used.
The PWM it's a very nice addition but I suggest you to do it if you've got more than one unit (I've got 2 atm), 'cause it's not switchable and it change permanently the synth's sound when the LFO's target are VCO or VCO+VCF.
grenert
Pase wrote:
@rarara
Sorry but I really don't know which schema it's been used.
The PWM it's a very nice addition but I suggest you to do it if you've got more than one unit (I've got 2 atm), 'cause it's not switchable and it change permanently the synth's sound when the LFO's target are VCO or VCO+VCF.

Well, that's not entirely true. It only has an effect when the pulse wave is selected. Triangle and sawtooth are not altered (at least in the mod described earlier in this thread).
Pase
grenert wrote:
Well, that's not entirely true. It only has an effect when the pulse wave is selected. Triangle and sawtooth are not altered (at least in the mod described earlier in this thread).

d'oh! You are right, I was wrong oops
rarara
Changing subject to the Volca Bass slightly - I guess the sync in and out are just standard mono jacks? Think I may relocate one and use the hole for my FM mod pot, to save drilling the faceplate. I may even be able to mount it on the PCB.

Had a look at darenager's distortion mod - its simple and my eyesight is decent, but the fact that I can barely see the resistor makes me worry that it will be tricky to remove and solder the wires in its place. waah
Heaven
Slightly off topic.. does anyone know where to buy Monotribe nowadays? can't even find it on eBay!
Pase
The monotribe it's been discontinued, you have to look for a second hand unit.
Heaven
Pase wrote:
The monotribe it's been discontinued, you have to look for a second hand unit.


OMG! why??? It's such an amazing piece. Hope they introduce another version or something similar soon.

I sold mine a while ago because I was being a stupid retard. Oh how I regret it now..
saldiamond
I rarely use mine.
But every time I pull it out to sell, I spend some time with it and come up with something interesting and have fun doing so.

I have considered modding it but I am sure at this point I would muck it up.
hamildad
I always think about a 10 year anniversary model that has MIDI & CV/gate as standard and no clicking, but otherwise I wouldn't change anything.

I even like the fact that the filter is non CC-able, it's wiggling or nothing...
darenager
I have been working on some new drum mod kits for the Monotribe, details here:

http://monotribemods.blogspot.co.uk/2015/11/xtreme-decay-drum-mod-demo .html

Also VCO mod is available again, the last run (really this time!)
rarara
darenager wrote:
I have been working on some new drum mod kits for the Monotribe, details here:

http://monotribemods.blogspot.co.uk/2015/11/xtreme-decay-drum-mod-demo .html

Also VCO mod is available again, the last run (really this time!)

hi daren - would there be a discount for both monotribe mods??

and off topic, but did you need some form of magnification to do the volca bass distortion mod?
darenager
^ PM me re the mods

The Volca mods are by Darren Glenn in Australia not me, but yes magnification would be recommended to work on the smt parts.
Pase
Slightly off-topic: Does anybody knows if it's possible to swing the monotribe with a Future Retro Swynx?
The Swynx has an analogue clock output so it should work with the sync in of the korg. I ask to J. from Future Retro and he said that he didn't have a korg to try it but it should work.
Are there other solutions to apply swing to the monotribe? (not the iphone app)

P.s.- via midi my 'tribe receive swing only for the synth part, not the drums. It's supposed to work this way?
neuroportal
Does anyone know of anyone who will install a Midi mod and click reduce into my 'tribe? This would be in the UK and payment, obviously, with it.

I would prefer it installed into the case, but I am open to suggestions.
rotallicso
neuroportal wrote:
Does anyone know of anyone who will install a Midi mod and click reduce into my 'tribe? This would be in the UK and payment, obviously, with it.

I would prefer it installed into the case, but I am open to suggestions.


Start here, or check DarenAger's recent posts to see if he's still doing them .. http://monotribemods.blogspot.co.uk/
neuroportal
Awesome. Thanks!
rotallicso
neuroportal wrote:
Awesome. Thanks!

erm - sorry - had no idea he'd actually posted two above you !
Karg
My attempt to mod the monotribe: http://karg-music.blogspot.de/p/monotribe.html

Much inspired by this thread!! Thanks!
grenert
Great first post! thumbs up
I look forward to hearing how you added the LFOs.
Have you managed to fit it all back into the case?
Pase
monotribe n.2, this time with MIDI I/O, darenager's VCO mod kit, VCO de-click,drum decay/frames (with knobs instead of switches), drum mute switches, and drum mix out.

WilliamHart
This is my first post on Muff Wiggler, or any forum for that matter, so be gentle… wink

I saw this guy mod his Monotribe to go into his Eurorack. http://www.matrixsynth.com/2012/08/korg-monotribe-in-eurorack-korg-ds1 0-on.html

Has anyone here tried this?

This seems cool, but what I think would be even better is to be able to control aspects of the synth parts (LFO and VCF, among other things) on the Monotribe with external CV. Has anyone found the schematics for the synth section? I've only been able to locate the schematics for the rhythm section.

Cheers!
stopthesignal
Quick question for anyone who has done the de-click mod. Have you noticed an intermittent glitchy sound when the gate is opening and closing a lot/quickly?
FrJK
Altitude909 wrote:
on the base board (the one with a speaker) there is a 0603 surface mount fuse marked FU1 (it as an M on it), check if that is blown

Thanks a lot for this hint. You saved me my monotribe :-)

It happened while I resoldered the output jack, because he was not giving proper signal ... but resoldering didn't helped ... Do you have any tip what else it could be? I now use the 3,5mm mini jack headphone output. That one is working well ...
Starspawn
Hmmm, is a decay stage after the gated mode possible?
When using it as an extra osc for other things thats the main issue.
Would a diode and a pot do the job perhaps?
zaphod betamax
[img][/img]super simple attenuator to tame the 8v cv hz/v from ms-20
to allow you to run monitribe in hz/v mode after adjustment

this should also work to allow you to control the Yamaha CS-x
family of synths. However, I do not have one to test.
Scott Willingham
Starspawn wrote:
Hmmm, is a decay stage after the gated mode possible?
When using it as an extra osc for other things thats the main issue.
Would a diode and a pot do the job perhaps?


Sorry, it's not very feasible. As you speculate, it would probably be possible to add a decay to the analog CV that controls the VCA. The problem is that once the microcontroller in the the MT has finished the generation of its envelope, it will assume the signal path is muted and auto-run its VCO tuning routines.
rotallicso
Quick query about the monotribe and MIDI i/o (& thru)

it's evident that there is no practical need for the pair of hex inverters on the MIDI org DIN spec guidelines for a monotribe
https://www.midi.org/specifications/item/midi-din-electrical-specifica tion

Now, I want to add small 2.5mm TRS jacks for In Out *&* Thru

Since 2014 there's a new guideline which caters for interference and I'm wondering, well, why not do it right, what's the harm
Image copy here http://hinton-instruments.co.uk/images/reference/promidi/midihw2.gif

This new spec shows a single non inverting buffer, now I'm a noob here, I believe this is essential on the Thru side
Assuming so, then why don't I just hook it up on the Out too ?

Why are other designs not needing the hex inverters on the Out, I'm asking for curiosity and to learn a bit

I'm also wondering if the lessons here will apply to some Arduino circuits
If I'm skipping the thru on those, should I forget the 7417 (or 7407 which I presume is compatible/same) ?

I have the 6n137 optos for my projects, one thing that's written up online somewhat confusingly is the value of the pull-up resistor after that opto (assuming that's the right lingo, why?) -if anyone can guide me in layman's terms to understand the best way to understand selection and to dismiss some of the schematics doing the rounds that'd be nice too

edit:not much footfall here, gonna ask this on the DIY sub forum as it's actually just a general query ...
.
see here >
https://www.muffwiggler.com/forum/viewtopic.php?t=160437
systmcrsh
finally got around to installing darenager's vco mod... fun stuff :))



got a buddy to drill the holes which came out pretty awesome... my soldering was a little crap, but it sounds good :)[/img]
Kennymester
Not really a mod per-say but I'm thoroughly impressed by the quality overlay that I got from styleflip.com. Makes it really easy to use the version 2 update.

Pase

+1 for Styleflip overlay, not cheap but useful and look good thumbs up
Majonymus
did some bending repairs today, found a hat to clap easy mod, first hat decay to sd noise decay, cause my hats were not sounding at all then a switch for claps



and midi in for mine seems to listen a little, but still not working fine u_u
rotallicso
There's a pointer earlier in the thread to the fuse type on the battery board being 0603, that may help experienced folks, but here's a screen grab of all the necessary details if you've blown one, like moi ..
TF16AT1.25 M = anti-surge 1.25A 32V
.
very easy to bridge the smd at more convenient spots

[/img]
rotallicso
If anyone's looking to source nice sockets to fit the gap between the output board and the voice board then these fit just neat if you get your sums right. They're 2.5mm TRS as i had some spare MIDI to 2.5mm TRS cables from a Line6 MIDI Mobilizer and there'll be no accidental cabling mishaps either. Pro Signal PSG08264.
.

.
One other contribution fwiw would be that sitting your optocoupler directly on the board would help space-wise (as opposed to sitting in a dip socket) i'll do this next time
.
Works perfectly, but what case scenarios have people observed that may push the midi i/o to fall over ? - i went with the 137 opto and 140R on the output side to account for the 3.3v VCC
420noscope
Nice stuff!
jimmie
Does anyone have a broken siwtch?

My monotribe's switch 4 (seq #4) had started having bad contract and it's finally dead. I opened the case try to fix it - hoping brewing dust or touch of contact cleaner would fix it - but it didn't seem to work. I've never seen that round switch and doesn't look like I can open it to clean the inside.. looking very fragile.

If somebody has some advice to fix it I'd appreciate.
marmad
Hey everyone!!

Sorry for my long absence... the last 2 years became engulfed by a long-overdue renovation of my 2000 sq.ft. (200 m²) studio and the death of my father last year.

So my Monotribe modification upgrades were shelved during that time (even though the design of the circuitry was finished and tested), but I'll be able to get back to it a little later this month - and the boards will finally be sent off to be produced.

In the meantime, I thought I'd start posting the schematics for it as I find the time to touch them up a bit and scan them, which might allow others to incorporate any pieces of it into their own designs they're interested in.

To begin with, here is the circuitry to generate CV (1V/Oct) and GATE OUTPUTS from the Monotribe, as well as the circuit to feed the EG into the Rhythm section, and the Click/Pop Suppression circuitry mentioned in my previous YouTube video.



Feel free to ask questions, modify, or condense as desired. For example, the circuit as shown uses all 4 sections of a TLC274 quad op-amp (with one op-amp being used to generate an alternate source for the VCA from my VCO2). But if you just wanted to generate the CV OUT, you could use a TLC272 dual op-amp instead. and eliminate the use of any switches or externally-mounted pots.

You'll need a decent voltmeter or DSO to adjust the 1V/Oct output - first setting the CV Offset trim (floor) with the lowest note, and then adjusting the 1V/Oct output using the highest octave multiple of that note.

(P.S. this is one sheet of a set of schematics - so some of my package choices or in/outs to the sheet are related to other sheets in the set).
Scott Willingham
Good to see you back, Marmad, and to see this thread bumped again!

The Monotribe is a special box. I love the Volcas and the Minilogue looks cool, but the tech in them is too tight to reverse-engineer and mod. The Monotribe is just right: portable, playable, yet enough room to work with and accessible circuits. Plus, the groove-box interface just works for me. I'm not generally attracted to sequencers, but the MT invites me to dive right in.
williambeucler
Not sure if this is the place to post my issue, but I've had the Monotribe a few years now, and I love it. I bought the Miditribe and installed it with no issues. All of sudden a month ago, the thing started clicking non-stop, and hasn't quit. I've pushed and pulled all the buttons, knobs, switches, and it just won't go away. I was thinking that maybe if I did the declick/capacitor solder modification, it could get rid of it. I've read that it's a common issue, but I just can't seem to get rid of it. I even took the batteries out for a day to see if it would reset itself, but no luck. The drum sounds seem okay, but once I add in the synth, there is that clicking again. If I add in the noise, the noise has no effect. If I modify the gates to full, and turn the VCA level to full, I can eliminate the clicks and hear some of the synth, but it's faint. Thanks.
marmad
williambeucler wrote:
Not sure if this is the place to post my issue, but I've had the Monotribe a few years now, and I love it. I bought the Miditribe and installed it with no issues. All of sudden a month ago, the thing started clicking non-stop, and hasn't quit. I've pushed and pulled all the buttons, knobs, switches, and it just won't go away. I was thinking that maybe if I did the declick/capacitor solder modification, it could get rid of it. I've read that it's a common issue, but I just can't seem to get rid of it. I even took the batteries out for a day to see if it would reset itself, but no luck. The drum sounds seem okay, but once I add in the synth, there is that clicking again. If I add in the noise, the noise has no effect. If I modify the gates to full, and turn the VCA level to full, I can eliminate the clicks and hear some of the synth, but it's faint. Thanks.

It sounds as if your trimpot adjustment (VR9) of the bias offset current to the VCA (the source of the normal clicks and pops that happen on the Monotribe) might have gotten out of whack, so that's the first thing you should check.

If you haven't watched my YouTube video on the subject, that might be a good place to start. As I mention in the video, I suggest replacing the stock Korg trimpot with a 10-turn trimpot for a more precise adjustment, but for your purposes, you can at least check if the bias offset is causing your problems without doing any desoldering/soldering. You'll need a decent voltmeter of some sort that has reasonable precision.

You want to check the adjustment of the bias current at the zero level of the Envelope generator, so make sure that no EG is happening when you do it. First read the voltage at resistor R95 (the side connected to transistor Q17), then, while checking the voltage at resistor R91 (also the side connected to Q17), adjust trimpot VR9 until the voltage is as close as possible to the one at R95.

If you are still having clicks happen constantly after this adjustment, then your problem is originating elsewhere. But the other modification mentioned in the video (the cap) will likely not solve your problem (or at least, it won't remove the source of it), since the stock Monotribe does not normally have a "non-stop" clicking problem; it only happens under certain conditions.

marmad
Scott Willingham wrote:
Good to see you back, Marmad, and to see this thread bumped again!

Thanks, Scott.

I've just been reading the previous 4 pages of posts that were made since my last visit here, and I had two responses to the posts you made:

I think you might have missed the series of posts I made on page 31 describing why the drum mods proposed by various posters earlier were not very good - or, in the case of BD "DECAY" & SD "DECAY" (actual gain adjust points of their respective circuits, and thus rather mislabeled by Korg), electronically "incorrect". For example, there's no reason for ON/OFF switches for the different drum outputs; simple add-on modifications to the associated pads provided by Korg can produce an OFF setting for the drum outputs automatically at one end of their respective POT settings (i.e. instant decay or zero gain).

Also, I noticed that you seem to prefer cutting traces on the Monotribe board as opposed to drilling holes in the case. That's interesting, because for me, the challenge is the exact opposite: I prefer to add mods that don't alter the original circuit in any way, but instead just insert extra circuitry for added features (usually with the added burden of drilling holes for pots/switches). I guess those are the two "opposing" directions of modding (in general).

With that in mind, I thought I'd re-post the mod I first mentioned back on page 31, but with the additional circuitry added that's included in the schematic I just posted above.

This mod feeds the EG into the unused rhythm section amp input, with each EG setting (saw, square, etc.) generating different accents on the rhythm (some of them producing very nice results). It requires:

1x 3.3 nF ceramic cap
1x 100k resistor
1x 100k log pot (for intensity)

At one end of the intensity pot adjust, the effect will be zero; i.e. stock Monotribe.

marmad
Here's a schematic for adding a non-destructive, completely separate, Pulse Width Modulated source to the Monotribe. In other words, this circuit doesn't modulate any signal on the Monotribe itself, but rather generates it's own square wave (synced to the VCO) that is pulse-width modulated by the envelope generator, and then fed to the summing amp.

To use it, you must tap off 3 points from the Monotribe (IC13 Pin 10, IC14 Pin 2, and IC17 Pin 8), as well as 3 power-supply points (+5V, Vbias, and Ground).

It uses 1 dual op-amp IC, 9 fixed resistors, and 3 pots (although you can replace any pot with fixed resistors if you don't feel you need the corresponding adjustment):

1x LM358 IC
1x 330k resistor
1x 270k resistor
1x 220k resistor
2x 100k resistor
1x 68k resistor
1x 47k resistor
1x 15k resistor
1x 4.7k resistor
1x 1M linear pot (initial pulse width adjust)
1x 100k linear pot (intensity adjust - one end will be zero modulation)
1x 10k logarithmic pot (volume adjust - one end will be zero volume; i.e. stock Monotribe)

BTW, this circuit, as well as many others (as mentioned back in my post on page 31 of this thread), will be included on boards which I'm currently (finally!) producing - although I've added circuitry for additional choices for the pulse-width output and modulation input.

Pase
Great marmad!
If you'll ever start moddin' other people's units I will buy my third monotribe and I'll send it to you.
Keep up good job! we're not worthy thumbs up
CeeJay
Thank you marmad for posting your mods! I will try them one day.
Scott Willingham
Love the new mods, Marmad. The accent mod is clever and looks like fun. Great bang for the buck! The PWM mod looks very well designed too. I think I'd want to have a cross-fader between the normal waveforms and the new pulse. Not sure I'm up for adding too many potentiometers sprouting out from my MT, however.

I look forward to seeing your PCB. Very tempting.
Scott Willingham
marmad wrote:
I had two responses to the posts you made:

I think you might have missed the series of posts I made on page 31 describing why the drum mods proposed by various posters earlier were not very good - or, in the case of BD "DECAY" & SD "DECAY" (actual gain adjust points of their respective circuits, and thus rather mislabeled by Korg), electronically "incorrect".


I did see those posts last year, but failed to comment on them at the time. I don't think extensive drum mods appeal to me much. I mostly feel like analog drum circuits have a fairly small sweet spot and I don't care much for long booming kicks or toms. In the meantime, I installed Daren's drum mod (very clean kit) and it hits a good compromise for me of variation and simple operation.

Some motion sequencing of the drum tones would be interesting... screaming goo yo

Regarding your drum circuits, I agree with the way you handled the decay mods for the hat and snare noise. Seems straightforward and clean. I'm not sure if I agree with your criticism of the common kick/snare-frame decay mods. My (mis-?)understanding of the tone generators is that they are simple resonant circuits and the amplifier gain not only changes the volume a bit, it alters the damping factor of the oscillation. So I think Korg's "decay" points are correctly used by effectively altering the emitter degeneration resistance. Unfortunately, while that works, it is a very tweaky adjustment.

On the other hand, your "gain mod" may also alter the resonance in a good way. I'll have to think about it more. confused

Edit: Ok, I see what you are doing. On one side of the pot's center setting, you are effectively doing the standard mod with a wrinkle: adding an AC coupling capacitor so you adjust the midband gain of the amp without disturbing its bias point. Good idea. On the other side of center, you are essentially just fading out the gain of the amp by loading down the collector side. At the extreme, this also mutes the path.
marmad
Quote:
I'm not sure if I agree with your criticism of the common kick/snare-frame decay mods. My (mis-?)understanding of the tone generators is that they are simple resonant circuits and the amplifier gain not only changes the volume a bit, it alters the damping factor of the oscillation. So I think Korg's "decay" points are correctly used by effectively altering the emitter degeneration resistance.


Q11 and Q15 (the NPN transistors for SD frame and BD) are simply unbypassed common-emitter amplifiers. Since the gain of the stage is approximately Rᴄ/Rᴇ (R56/R64 and R69/R78 respectively), varying Rᴇ (the common "decay" mod) varies the gain - but it also varies the DC collector current, thus changing the frequency response of the amp (which may lead to distortion).

Obviously, one can change the gain of a CE amp this way, but not only is it normally considered poor practice (for the reasons mentioned above), but just adding resistance in parallel with the respective Rᴇ of each transistor means you automatically alter the stock Korg output sound.

For example, the normal Rᴇ of the BD amp is 470Ω; a common "BD DECAY" mod (top waveform in the following DSO image) simply makes Rᴇ adjustable between 183 - 395Ω, thus never being able to achieve the original frequency response of the stock BD OUT (bottom waveform):



My alternate mod is just a well-known, improved method of gain adjustment for CE amps. Varying the pot bypasses more or less of the AC signal, increasing the gain, while also potentially reducing the volume at the following stage. The overall frequency response will remain essentially unchanged at various gain settings, with the middle position of the pot (top waveform) almost precisely equal to the stock Korg output (bottom waveform - BD OUT):

Scott Willingham
marmad wrote:
My alternate mod is just a well-known, improved method of gain adjustment for CE amps. Varying the pot applies more or less of the signal present at the emitter to the following stage. The overall frequency response will remain essentially unchanged at various gain settings, with the middle position of the pot (top waveform) almost precisely equal to the stock Korg output


I don't think your description of the circuit really matches the operation. The way you have connected the potentiometer is with the wiper grounded. This does not couple the emitter signal to the following stage. In effect you have two separate circuits: 1) shunting the emitter through a series R-C to ground. This adjusts the midband gain of the CE stage, yielding longer decays than the stock circuit. 2) Adding a parallel load to the collector (again AC-coupled). This reduces the amp's gain at the other end of the knob range, which shortens the decay from stock.

Your results demonstrate that this is an effective circuit and though I haven't tried it, I agree it is superior to the alternatives that you criticize. But IMO, your description of the circuit's operation is misleading.
marmad
Quote:
I don't think your description of the circuit really matches the operation.

True, I wrote the post quickly and my mind was elsewhere when writing. The description should read (now fixed): "Varying the pot bypasses more or less of the AC signal, increasing the gain, while also potentially reducing the volume at the following stage."

OTOH, your description of the circuit is also a bit misleading and not really accurate:

Quote:
1) shunting the emitter through a series R-C to ground. This adjusts the midband gain of the CE stage, yielding longer decays than the stock circuit.

Bypassing the CE amp alters more than just the midband gain, and this is not a specific adjustment to the "decay"; it's a gain adjustment of the entire envelope of the sound (see my previous statement about Korg's rather misleading labeling of those points).

Quote:
2) Adding a parallel load to the collector (again AC-coupled). This reduces the amp's gain at the other end of the knob range, which shortens the decay from stock.

No, the other end of the pot doesn't affect the amp's actual gain settings at all, and again, it is not specifically related to "decay" - it reduces the AC output volume of the entire envelope before the next stage.

So, one end of the pot bypasses all of the emitter resistor, leading to maximum AC gain, while having little affect on the volume before the next stage. The middle of the pot is equivalent to no bypassing of the emitter resistor, with just a small effect on the volume (i.e. almost stock Korg gain/volume). The other end of the pot just reduces the AC volume to zero before the next stage, with little affect on the actual gain setting of the CE amp.

This is not, to be sure, the most elegant way to do this - but it was designed with three strict rules in mind:

1) It should be non-destructive. In other words, there should be one position of the control which produces the stock Korg output.

2) It should provide zero volume at one end of the control. In other words, no additional switches, etc, should be needed to mute the sound.

3) It should only use the existing tap points (e.g. BD DECAY, BD OUT, etc) that Korg provides. In other words, any user, even those with little electronics knowledge, should be able to easily implement it.
Remork
hey

just a quick heads up to the wigglers - came upon this thread looking for a way to eliminate that 200-250Hz hum that was really bugging me.
made the whole thing useless- it was so bad it sounded like a constant ringmod with a B note.
so i did Snyder80's led matrix dehum, combined it with the sound advice of replacing R1 with 80 ohms. problem solved! great.

while the MT was open, i decided to poke around for the other mods.
so i installed the VCA declick mod (also great!).

i'm going to install HH decay and a SN noise decay on/off/on switches.
i tried marmad's way of doing the decay, but especially on HH and SN the cap you choose for longest delay time always seems to influence the circuit, so you never get back to the original sound.
i could get it to be as short, but not with the same attack in the sound.
so i'll end up just adding parallel timing caps. works for me.

Snare frame length i'm not interested in.

while trying stuff in the BD section, i accidentally f#$%^ stuff up, so i turned a problem into a challenge smile and ended up replacing R73 and R74 with a stereopot - well, kind of - and got myself a tuneable kick!
here's how that works:



this way it spans just over an octave (low E to F or something.)
of course, it's a tuned oscillator, so the length mod works more on some tunings (the middle part is closer to the ideal frequency for the circuit, i guess.) so it's all a bit interactive. but hey.
for BD decay i put in a 220R fixed resistor, parallelled with 10uF for a bit more oomph, and a 1K pot in series.
goes from original length to oscillation. on some notes. hah.

next, checked out the Clap mod someone posted - shorting snare noise out to snare frame out. it basically just alters the mix of the snare noise; normally that has a 220K mix resistor, and by connecting it to the snare frame output you run it through a 22K. big difference, and indeed more clap like. so i put that connection on a 100KA pot: now it goes from original snare to clap. which is nice.

anyway, thanks to the forum, just wanted to contribute!
zaphod betamax
Also noticed that if you use the S&H LFO mode on the Monotribe and set the speed to slowest, that when you engage the drums, the S&H changes with the beat!

This works great because I have the synch out into trigger on the S&H on the Korg MS-20K which in turn gets its S&H LFO in step with the beat.(built with pink noise as input and output to HPF Fc)
As the MS-20Ks CV and trigger are fed into the Monotribe, it also allows me to use the Monotribe as a third oscillator!
marmad
Remork wrote:
i tried marmad's way of doing the decay, but especially on HH and SN the cap you choose for longest delay time always seems to influence the circuit, so you never get back to the original sound.
i could get it to be as short, but not with the same attack in the sound.

It's true that you can't really add any capacitance or resistance to an RC filter without inevitably influencing the sound to some degree, but it's not really hard to get close to the stock Korg sounds with my circuit. But if you try to get very long decay times, the trade-off (and there's always a trade-off) is the amplitude. The bigger you make the added capacitance, the harder it is to get the original decay length at the same volume.

For example, look at the two Hi-Hat waveforms and FFTs below; they're almost identical (both with ~600Hz peak frequencies and ~80ms decays), but the second one has ~15mVpp less initial amplitude. The first is the stock Korg HH out, and the second is using my circuit with an added 22nF - which is what I've found to be a good trade-off value between slightly less volume and longest decay time.

Stock Korg HH:




Added HH decay circuit (22nF and pot near center position):

Remork
funny, i ended up with a 22nF as well.. but just plain switchable. (other cap is a 6.8nF for just a hint of extra hihat.)

i totally trust you on the analytic side of things - but it just didn't sound quite the same. seriously, i just don't get it
maybe the cap values i tried were too high? i may have given up too quickly on your method, dunno.
anyway, quite happy with what i got now.

meanwhile, also threw in the VCO mute.
midi I/O i already had.
now i just want to run a full mix drum output (don't really want the separate outputs, got other gear for that) and a firmware update - got a TRRS cable to 3x RCA on a fleamarket. think it's from an old camcorder. hope it'll work.
marmad
Remork wrote:
funny, i ended up with a 22nF as well.. but just plain switchable. (other cap is a 6.8nF for just a hint of extra hihat.)

i totally trust you on the analytic side of things - but it just didn't sound quite the same.

Well, the resistors effect the amplitude at different settings as well. I used a 22k resistor and 2k log pot for the voltage divider, and I used a 220k resistor for the discharge resistor.

With these values, you don't get quite zero sound at one end of the pot, but I couldn't hear (or see on the oscilloscope) any difference at all between the stock Korg hi-hat and when the pot was near the center position. It's possible the discharge resistor could be lowered still more without altering the stock sound too much.
Remork
hm. i tried the 47K as described for discharge R, and - iirc - a 100K with a 10K pot. i don't know, i think i understand the theory behind your method, but my implementation just didn't quite do it for me. plus i wanted to seal it back up, and i don't really have much use for separate drum mutes.. to each his own, i guess.

as for now, i did the 2.1 firmware upgrade, and it's running happily along the MS20 as a third oscillator. tracking seems fine across most of the keyboard range, up to the high G. the five keys after that just play the same high G, or slightly sharp versions of it smile
it's nice to have a third oscillator that has it's own LFO, really makes thicker sounds come alive.

need to try if, instead of playing C notes for calibration as per the manual, i could tune to something like fifths and go for chordal stuff. smile
edit: it works, but it'd probably be more succesful in v/oct mode.. if i play an F for calibration, it plays a bit short of a G when i hit a C note on the MS20. it's close enough to maybe get away with, esp with some modulation on the MT vco, but it's not quite spot on. i would expect v/oct to be more of an accurate parallel shift.
zaphod betamax
Easy fix for this. The Monotribe can not read +8V on Hi C on the MS-20.
Take the CV and divide it in 2 and then port it to the Monotribe. fixed.



Remork wrote:
hm. i tried the 47K as described for discharge R, and - iirc - a 100K with a 10K pot. i don't know, i think i understand the theory behind your method, but my implementation just didn't quite do it for me. plus i wanted to seal it back up, and i don't really have much use for separate drum mutes.. to each his own, i guess.

as for now, i did the 2.1 firmware upgrade, and it's running happily along the MS20 as a third oscillator. tracking seems fine across most of the keyboard range, up to the high G. the five keys after that just play the same high G, or slightly sharp versions of it smile
it's nice to have a third oscillator that has it's own LFO, really makes thicker sounds come alive.

need to try if, instead of playing C notes for calibration as per the manual, i could tune to something like fifths and go for chordal stuff. smile
edit: it works, but it'd probably be more succesful in v/oct mode.. if i play an F for calibration, it plays a bit short of a G when i hit a C note on the MS20. it's close enough to maybe get away with, esp with some modulation on the MT vco, but it's not quite spot on. i would expect v/oct to be more of an accurate parallel shift.
zaphod betamax
Is there a mod that will allow an external synths ADSR to control the VCA or VCF, along with trigger in?
dwnstream
Hey all! I came across the monotribe cv/gate breakout boxes posted a few years back in this thread. I really need one of those, hopefully you guys are still making them?

I tried to PM first, but the forum said I couldn't PM unless I've posted at least once. So here is a post! Altitude909, expect a PM from me shortly.
zaphod betamax
Greetings from Sarnia, Ontario!
These are fairly easy to build DIY from a TRRS 1/8" cable with the
end going to 1/4" in my case,or maybe 1/8" in your case.

Hack apart an AV cable for video, and this should do the trick!


dwnstream wrote:
Hey all! I came across the monotribe cv/gate breakout boxes posted a few years back in this thread. I really need one of those, hopefully you guys are still making them?

I tried to PM first, but the forum said I couldn't PM unless I've posted at least once. So here is a post! Altitude909, expect a PM from me shortly.
Altitude909
dwnstream wrote:
Hey all! I came across the monotribe cv/gate breakout boxes posted a few years back in this thread. I really need one of those, hopefully you guys are still making them?

I tried to PM first, but the forum said I couldn't PM unless I've posted at least once. So here is a post! Altitude909, expect a PM from me shortly.


hmm. several ppl have asked about these so maybe a small run is in the future..
zaphod betamax
mods (which require no soldering)
1)Run two Monotribes off the same CV.

2)Run the headphones out of MT #1 into audio in #2, then headphone out
on MT #2 into audio in MT #1
JayEm
zaphod betamax wrote:
mods (which require no soldering)
1)Run two Monotribes off the same CV.

2)Run the headphones out of MT #1 into audio in #2, then headphone out
on MT #2 into audio in MT #1

won't that just create a feedbackloop? assuming you're even playing both, since the audio in only works when the internal synth is playing
zaphod betamax
Ahhh, but I am playing them at the same time!
MS-20 Kit #1 CV out and trigger to MS-20 Kit #2
with Y-splitters and attenuators to both CV ins on the
Monotribe #1 and #2.

This could also be achieved with a V/octave controller keyboard
as the Monotribe speaks both Hz/V and Volt/Octave.

And I could play them in tandem without any of this....
You put #1 and #2 into Record/Play and wire as I said
previously, and yes it is a feedback loop but it
exponentially cooler than the feedback loop that one
Monotribe does as a single entity.
(surely you have routed the headphones
back into the Audio In!)
In the above mode you could (for example) have drums
and press a note on MT #1 and on MT#2 mute the drums
press a note (thus opening the filters on both MTs).
It sounds golden!

And you will note in my "mod", I note "run two Monotribes
off the same CV", which implied that they are being controlled
(played ) at the same time.
In my case it is Master MS-20Kit #1 controlling another
MS-20Kit and the two Monotribes.
Everything shares the same CV and trigger.




JayEm wrote:
zaphod betamax wrote:
mods (which require no soldering)
1)Run two Monotribes off the same CV.

2)Run the headphones out of MT #1 into audio in #2, then headphone out
on MT #2 into audio in MT #1

won't that just create a feedbackloop? assuming you're even playing both, since the audio in only works when the internal synth is playing
JayEm
Ah, misunderstood your post. I thought you were implying you could CV control via the headphone out.

zaphod betamax wrote:
Ahhh, but I am playing them at the same time!
MS-20 Kit #1 CV out and trigger to MS-20 Kit #2
with Y-splitters and attenuators to both CV ins on the
Monotribe #1 and #2.

This could also be achieved with a V/octave controller keyboard
as the Monotribe speaks both Hz/V and Volt/Octave.

And I could play them in tandem without any of this....
You put #1 and #2 into Record/Play and wire as I said
previously, and yes it is a feedback loop but it
exponentially cooler than the feedback loop that one
Monotribe does as a single entity.
(surely you have routed the headphones
back into the Audio In!)
In the above mode you could (for example) have drums
and press a note on MT #1 and on MT#2 mute the drums
press a note (thus opening the filters on both MTs).
It sounds golden!

And you will note in my "mod", I note "run two Monotribes
off the same CV", which implied that they are being controlled
(played ) at the same time.
In my case it is Master MS-20Kit #1 controlling another
MS-20Kit and the two Monotribes.
Everything shares the same CV and trigger.




JayEm wrote:
zaphod betamax wrote:
mods (which require no soldering)
1)Run two Monotribes off the same CV.

2)Run the headphones out of MT #1 into audio in #2, then headphone out
on MT #2 into audio in MT #1

won't that just create a feedbackloop? assuming you're even playing both, since the audio in only works when the internal synth is playing
zaphod betamax
May I add that I enjoy the MT when not in auto-tune mode, where keyboard mode is not selected. I get around the same thermal warmup time as my MS-20Ks.

Also, since that pesky auto tune algorythm is disabled, you get subtle mistunings from two Monotribes receiving the same CV.
(and most people have more than one monotribe?)

Only tested in hz/V. The last time I had a V/oct synths was my Moog Prodigy, and I sold that back in 1991!
maltemark
Someone should really port the monotribe oscillator into eurorack, the squarewave is so full of nice, nice character that I miss it especially.
mckenic
http://pulplogic.com/product/monotron-e/
stopthesignal
Just to offer some follow-up on the helpful de-click mods posted here, I originally did the de-click mod with a 4.7uF electrolytic capacitor. It certainly reduced the clicks, but it also introduced an odd, intermittent glitch sound when gating the VCO. It sounded something like the VCO going through its entire frequency range, low-to-high, in a very small fraction of a second. It was subtle, but definitely noticeable. I suspect it was related to the auto-tuning algorithm.

I replaced the 4.7uF electrolytic with a 2.2uF Film capacitor and now the glitch is gone (as well as the clicks, of course).
zaphod betamax
Just sort of effect did it have on WIDE and NARROW mode, where auto-tune is diabled?


stopthesignal wrote:
Just to offer some follow-up on the helpful de-click mods posted here, I originally did the de-click mod with a 4.7uF electrolytic capacitor. It certainly reduced the clicks, but it also introduced an odd, intermittent glitch sound when gating the VCO. It sounded something like the VCO going through its entire frequency range, low-to-high, in a very small fraction of a second. It was subtle, but definitely noticeable. I suspect it was related to the auto-tuning algorithm.

I replaced the 4.7uF electrolytic with a 2.2uF Film capacitor and now the glitch is gone (as well as the clicks, of course).
stopthesignal
zaphod betamax wrote:
Just sort of effect did it have on WIDE and NARROW mode, where auto-tune is diabled?

The glitch was there no matter what mode that switch was set to. I'm not really convinced that auto-tune is disabled in WIDE/NARROW when the sync in jack is set to Sync mode rather than CV/Gate mode, but I also don't know for sure that this glitch was related to the self-tuning algorithm.
zaphod betamax
Do you think the fact that a film capacitor has no polarity, unlike an electrolytic has any bearing on the glitch?
Dreamfish
Hi Muff Wigglers

been modding the hell out of my Monotribe of late thanks mainly to this thread and Daren's excellent mod kits.

I really want to integrate a small analogue delay pedal inside the MT just on the synth voice and using the internal batteries (running at 9V) for an all in one portable box of delights.

Got a cheap Joyo JF-33 which seemed ideal as I can detach the pots and surface mount them to the top of the MT's front panel (eventually).
Connecting the synths VCA output directly from the board into the pedal worked fine.
Now connecting the pedals 9V battery connectors to the +/- on the inside of the MT's battery compartment makes it turn on however with the signal from the VCA going through but no effect from the pedal even when it's LED is o

I'm no electronics expert by any stretch but wondering if there's some other way I should be connecting the pedals negative somewhere else onto the board perhaps?

Also am I right in thinking if I do get the pedal working properly from the MT's internal batteries that breaking the VCA's direct signal to the main output and feeding the pedals output from there is going to be that easy? confused

thanks in advance
InDex
Hello all, I realize this is reaching back a ways but in response to young Zaphod (who plays it safe [sorry, that'll be my one and only name joke for a while.]) there was this video for external control of the VCF envelope: https://www.youtube.com/watch?v=cDWL5MSgoq0 there was some speculation in the comments section about using it to control the VCA envelope as well but I don't think that any consensus was reached in that area. Just thought I'd put it out there.

Cool, thanks for having this community, happy to be here. Sorry if my posts are a bit sloppy at first, it's been over 1.5 decades since last I said anything on the internets.
zaphod betamax
PLEASE IGNORE: FOUND IT!
sixart
Hello all! About to embark on my first modding journey thanks to your shared wisdom here. I wanted to add that I used a CTIA<->OMTP adapter to connect a TRRS headset splitter into the Monotribe for MIDI control. It was what I needed to connect with CV on the second ring of the TRRS.
zaphod betamax
Has anyone build a DIY MIDI OUT (only) for their monotribe?
In theory this would act as a CV(Hz/V) S_trig to MIDI adapter when connected to an MS-20???
shurikenyo
How about VCF...can we control the filter cutoff with CV from a eurorack LFO or ENV? Or will the monotribe blow up? internal power rail is 5V right...wonder if it can handle +-12V hmmm.....
zaphod betamax
Does anyone know where to get that little 5 pin? cable that connects
with the serial port on the Monotribe. I want to fab my own MIDI OUT (only)
and want to keep my DIY work as neat as possible.
zaphod betamax
Internal to the VCF is +3.3V, you would have to attenuate whatever signal.
Try tapping a signal into the wiper on the cutoff pot. Can't say how the Monotribe would react. Probably have to crowbar the signal so it does not exceed 3.3V.

shurikenyo wrote:
How about VCF...can we control the filter cutoff with CV from a eurorack LFO or ENV? Or will the monotribe blow up? internal power rail is 5V right...wonder if it can handle +-12V hmmm.....
CeeJay
zaphod betamax wrote:
Does anyone know where to get that little 5 pin? cable that connects
with the serial port on the Monotribe. I want to fab my own MIDI OUT (only)
and want to keep my DIY work as neat as possible.


Do you mean the 6 pin connector?
You need a JST PHR-6 2mm connector housing like this:
https://www.conrad.de/de/buchsengehaeuse-kabel-phr-jst-phr-6-rastermas s-2-mm-1-st-740728.html

And the matching crimp contacts or ready made crimped cables like this:
https://www.conrad.de/de/litze-gecrimpt-serie-ph-200-mm-808935-jst-748 475.html

Sorry, I have only the links to a german ekectronic shop, since I bought mine there.

For MIDI out you need only 3 cables and it's probably much easier to solder directly to the underside of the 6 pin serial connector.
zaphod betamax
I've also been told a PS2 mouse contains the same connector.
Have not been able to confirm this.
bitflip
zaphod betamax wrote:
Does anyone know where to get that little 5 pin? cable that connects
with the serial port on the Monotribe. I want to fab my own MIDI OUT (only)
and want to keep my DIY work as neat as possible.


This is the one i got - it fits perfect:

https://www.sparkfun.com/products/10361
zaphod betamax
Thanks! I realize now it is a 6 pin JST plug, I have been able ot find it on amazon.ca and mouse.ca.




bitflip wrote:
zaphod betamax wrote:
Does anyone know where to get that little 5 pin? cable that connects
with the serial port on the Monotribe. I want to fab my own MIDI OUT (only)
and want to keep my DIY work as neat as possible.


This is the one i got - it fits perfect:

https://www.sparkfun.com/products/10361
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