[IC] General Midi (GM) euro module - any interest?

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fitzgreyve
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[IC] General Midi (GM) euro module - any interest?

Post by fitzgreyve » Sun Mar 15, 2020 6:32 am

I'm in the early stages of designing a euro general midi module using the SAM2695 datasheet

Ideally I'd go for a yamaha DB50XG, but the are long out of print (so expensive), too big (in euro terms), and consume significant power.

problem with the SAM2695 for DIY is that it's a QFN44 package - problematic to solder by hand, so ideally this needs to be based on a pre-made module

So, I'll probably be going with a euro packaging of the DreamBlaster Synth S2 General MIDI Daughterboard - currently EUR 35.00 plus shipping and vat (which puts it at eur 60.50 shipped to the UK, slightly cheaper chinese version available on ebay!)

probable spec:
- ideally 6HP module (may need to be 8HP if all the options below included)
- L and R out on separate jacks (buffered, with possible output volume control if space allows)
- MIDI in - i tend to use deltron 690 series for midi connectors datasheet
- possible midi in TRS jack if space available
- possible midi thru if space available
- midi input activity led (again, if space allows)
- power: SAM2896 needs about 20ma +5V (derived from +12v), plus a few more mA for buffers etc.
- probably some SMT components (again, a space issue) - but nothing smaller than 0805 and SOIC
- panel black FR4 or black on silver Aluminium.

For clarity, the SAM2695 doesn't need any microprocessor/arduino/rasp-pi to operate, just the normal midi input circuitry, and ideally some audio output buffering.

Is this a "one off", or would anyone else be interested ? panel preferences ?
Under developement:
- Nothing at the moment!
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Re: [IC] General Midi (GM) euro module - any interest?

Post by StrangeCaptain » Sun Mar 15, 2020 10:52 am

Noob Q:
do GM have CV/Gate out?

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fitzgreyve
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Re: [IC] General Midi (GM) euro module - any interest?

Post by fitzgreyve » Sun Mar 15, 2020 11:00 am

No, this is just midi to audio, no cv or gate.

Expert sleepers "General CV" module probably uses the same core DSP IC with CV/gate in - more faciltiies, but not DIY.
Under developement:
- Nothing at the moment!
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https://fitzgreyve2.blogspot.com/

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Re: [IC] General Midi (GM) euro module - any interest?

Post by weasel79 » Sun Mar 15, 2020 11:56 am

in general i think this is a very interesting idea, but looking at the midi implementation of the sam chip it would kind of a wasted opportunity to not include a little MCU that reads some CVs to alter the sounds.
if you just do midi control only, then why have it in a modular surrounding anyways?

generalizing, i think there's a ton of untapped potential in (ab)using general midi rompler chips, but you will only generate siginificant interest if you do something extraordinary with it.

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Re: [IC] General Midi (GM) euro module - any interest?

Post by forestcaver » Sun Mar 15, 2020 12:08 pm

Looks intersting and fun
My thoughts:
If midi in, audio out, no cv, then why eurorack? Eurorack hp and power is expensive!
The board you linked is really expensive compared to the chip and doesnt look like it adds any real functionality - unless I am missing something?
QFN is not that hard to hand solder (done quite a lot of them by hand and I’m not very skilled...)

Looks like it could be a fun,cheap, standalone synth... ???? Nice idea....

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Re: [IC] General Midi (GM) euro module - any interest?

Post by ixtern » Mon Mar 16, 2020 7:29 am

I have a working prototype of such module (GM/GS) with much better DreamBlaster_X2 and Arduino Mega Mini controller.

My module can be directly controlled from the MIDI keyboard or sequencer, 16-channel 81 voices polyphony, may have loaded different sound banks (although there are not so many coz it's proprietary format), and has controlled by encoders/MIDI some parameters for every channel, like Attack/Decay/Release, Reverb time, Filter Resonance.
IMG_20200316_131537.jpg
ArduinoSequencer.pdf
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Last edited by ixtern on Mon Mar 16, 2020 12:51 pm, edited 1 time in total.

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Re: [IC] General Midi (GM) euro module - any interest?

Post by resynthesize » Mon Mar 16, 2020 10:57 am

interested, but agree with other posters that providing some level of CV/gate control would make this a lot more fun.

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Re: [IC] General Midi (GM) euro module - any interest?

Post by EATyourGUITAR » Mon Mar 16, 2020 11:41 am

do you have a hand held hot air reflow station? you really don't want to spend $35 on that PCB. you can get the hot air machine for $60.
WWW.EATYOURGUITAR.COM <---- MY DIY STUFF

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Re: [IC] General Midi (GM) euro module - any interest?

Post by av500 » Tue Mar 17, 2020 6:04 am

fitzgreyve wrote:
Sun Mar 15, 2020 6:32 am
I'm in the early stages of designing a euro general midi module using the SAM2695

Is this a "one off", or would anyone else be interested ? panel preferences ?
I designed a Eurorack "MIDI" module a few years back using the VS1053B chip. I put MIDI in quotes since it does not have MIDI-in, who needs MIDI in Eurorack anyway ;)

instead you control the General MIDI instrument or drum voice using pots and CVs and V/oct and gate, since the chip is polyphonic you can layer several instruments on top of each other, tuning them all using pitch bend or spreading them octaves apart. if you "sort" the GM instruments a bit you can get some smooth blends between voicings. and of course you can get mayhem with random CVs :)

When ES came out with "General CV" I basically shelved it.

here is a video and a soundcloud snippet, I can post some pics tonight...



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Re: [IC] General Midi (GM) euro module - any interest?

Post by S0210 » Fri Apr 10, 2020 10:18 am

fitzgreyve wrote:
Sun Mar 15, 2020 6:32 am
I'm in the early stages of designing a euro general midi module using the SAM2695 datasheet
Ideally I'd go for a yamaha DB50XG, but the are long out of print (so expensive), too big (in euro terms), and consume significant power.
problem with the SAM2695 for DIY is that it's a QFN44 package - problematic to solder by hand, so ideally this needs to be based on a pre-made module
So, I'll probably be going with a euro packaging of the DreamBlaster Synth S2 General MIDI Daughterboard - currently EUR 35.00 plus shipping and vat (which puts it at eur 60.50 shipped to the UK, slightly cheaper chinese version available on ebay!)
[...]
What about a 3U 16HP module?

Image

Actually Serge (from DreamBlaster) is consideting a new Eurorack module. (Not this one.) Reaching out to him for technical advices could be a good idea.

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Re: [IC] General Midi (GM) euro module - any interest?

Post by Sandrine » Fri Sep 18, 2020 11:28 pm

I just DIY'ed a SAM2695, it is possible to do a QFN48 0.4mm breakout!
Was well worth it too, here's my little voyage over the past couple of days...


I have 3 more so going to pop one into my GM MIDI module and get rid of that scrappy VS1053 I put in there. BTW Drums are worth it by themselves, very nice chip!

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Re: [IC] General Midi (GM) euro module - any interest?

Post by Sandrine » Sat Sep 19, 2020 9:04 am

So, I was thinking about what kind of module this would need to be to be feasable
The one I have built (soon to get this chip) has a sequencer built in and a 64Mbit (8 meg) EEPROM for recording stuff as MIDI but as this chip isn't in it yet, doesn't take advantage of any of the features.

The SAM2695 also has a mic input, I'm assuming for a sort of karaoke rig? That can have echo applied so that would be an input.
Echo slave times (3) can be programmed L/R which is great for ping-pong & rhythmics..
A formula of CC val * 3 yields a 3mS resolution for syncing to a clock which is close enuff
There's EQ bands, spacial/chorus (5 controls)/reverb(with room sizes)/echo FX that could be CV controlled, as well as some standard stuff like glide, sustain, vibrato, pitch shift, etc. but there's a tuning structure that may be of interest to scala users (+/-64 cents via sysex)

Then there's a whole other bank of instruments which I haven't tried yet, most have the same names but must be different somehow. There's also 5 drum sets
Oddly though, it doesn't respond to Cut/Rez (CC74/71) messages which is a bit disappointing so the EQ probably takes the place of those. As the EQ is variable band I suppose it would sound similar at least to the 5khz range, but no Q control so assume Q=1?

The mic+echo control is different from the instrument echo so creating a feedback patch could make some decent echo FX (up to 320mS) with the resulting output panned stereo & spacialized (L/R delay) which might be a decent feature to put on the panel

Well just my thoughts....
I'll post an update once the SAM2695 is in my proper MIDI module!

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Re: [IC] General Midi (GM) euro module - any interest?

Post by fitzgreyve » Sun Sep 20, 2020 11:11 am

Sandrine wrote:
Fri Sep 18, 2020 11:28 pm
I just DIY'ed a SAM2695, it is possible to do a QFN48 0.4mm breakout!
I like your approach of using the 3D print template for positioning.
Under developement:
- Nothing at the moment!
---------------------------------------
https://fitzgreyve2.blogspot.com/

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