Korg X-911 modification into a --> MS-911

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SMS303
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Korg X-911 modification into a --> MS-911

Post by SMS303 » Sun Mar 14, 2010 5:03 pm

I have the luxery for owning 2 Korg X-911's and a friend did point me to the MS-911 mods. Unfortunaly we can't find any modification schematics.

Image into --> Image

Specs:
This is a Korg X-911 that I have re-built to a modular synth. The original X-911 Guitar Synth actually contains much more than is obvious on the front panel:

# 1 pre-amp, dist unit, P-V converter and envelope follower/trig detector
# 1 multi-waveform, multi-octave output MS-20-style VCO with both lin and log CV
# 1 MS-20-style VCF
# 3 MS-10-style VCF:s (discrete KORG35) used by the Bass, Tuba and Trumpet presets.
# 8 VCA:s
# 9 simple EG:s

I have made most of these modules accessable at the front panel and layed out like a modular synth. The synth is then packed into a chassis that fits nicely in my MS-rack. The modules are pre-patched like the original 911. VCF 3 and 4 also have a LPF/HPF switch. The modules are:

# 1 x External Signal Processor: Input level, Range, Portamento knobs. Input, Dist out, Env out, Trig out, Hz/V out jacks.
# 1 x VCO: Octave, Coarse, Fine, CV1, CV2, 8" PWM, 16" PWM knobs. Hz/V, V/oct, CV1, CV2, 8" PWM, 16" PWM inputs, 16" sqr, saw, pulse, 8" sqr, saw, pulse, 4" sqr, saw output jacks.
# 4 x VCF: Cutoff, Resonance and Env CV knobs. LPF/HPF switch on VCF 3 and 4. Input, output, Env and CV jacks.
# 2 x Active filter: Tone knob, Input and output jacks.
# 6 X VCA: Input and output jacks.
# 2 x AR Envelope: Attack and Release knobs, Trig in, output jacks.
# 3 x D Envelope: Decay knob, Trig in, output jacks.
# 1 x 8 input mixer: Level knobs, input jacks.
# 1 x Output module/VCA: Volume and CV knobs, CV in and out

I'm no technician and can't tell if there other mods possible.
The X-911 schematics are free and easy foundable on the net.

I think of these extra's (if possible):
- 8x Output module/VCA: Volume and CV knobs, CV in-/out instead 1 output module/vca
- filter notch out
- volume attuenator for the distortion out
- ??????????????..............

Like i said, i'm no technician, so if someone can help me with a modification schematic i would appreciate much! :tu:
------------> Jaime Murray does Capua.... ------------------------------------------>

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Post by Tim Stinchcombe » Sun Mar 14, 2010 5:57 pm

Wow, that looks real nice - it is giving me ideas for my X-911 (which was a speculative buy, and I haven't even powered it up yet...).

It appears most of the links from the various blogs are dead, but Google is your friend, and it didn't take long to find 'ericg's' site:
http://hem.bredband.net/elmuced/ericg.htm
with the MS-911 page:
http://hem.bredband.net/elmuced/x911.htm
Contacting him would probably be the best place to start - contact details on the 'contact' page!

And, damn!, this looks good:
http://hem.bredband.net/elmuced/ms_sys.htm

Tim

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Post by SMS303 » Sun Mar 14, 2010 6:16 pm

Thanks for the reply Tim! :tu:

The specs were copy'd from synthforum.nl and i hadn't seen the website before.
I will contact Eric G. and ask if i can have a copy of the mod schematics.... me hope soo! :hail:

Currently i'm PM-ing with another Dutch guy to overthink the possibillities of the X911.
I hope we'll soon have an idea of all the work, design a frontplate and how we will do all the work.

If the costs for materials are reasonable there are at least 3 Dutchmen, including me, who wants to modificate their X911's

I hope the costs for some frontplates are reasonable too. Otherwise we have to wait until there are 5 or 10 persons
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Post by dougt » Mon Mar 15, 2010 3:58 am

Yeah I remember coming across the MS-911 years ago before the page went down. I have kept my X-911 thinking I'd modularize it some day so I would be interested in a front panel too. Hope you can get the mod schems out of Eric G. If not you can probably figure it all out if you have the X-911 schems.

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Post by Pozor » Mon Mar 15, 2010 3:20 pm

+1 more Dutchman

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Post by SMS303 » Wed Mar 17, 2010 12:37 am

Received from Erik G. :)
Erik G. wrote:You are welcome to do so! :-)
I am sorry but I have only the original schematics with hand drawn changes on it. Not very complete I'm afraid.
/Eric
Many thanks Eric for the authorisation and starting this amazing project :tu:

The more technical Dutchguy did found outthat the X911 do own 1 VCO and waveshapers, which do shape/bound the wave into those used by the instruments. Hopely there shall be at least 1 waveshaper unused and that waveshaper can be used for a simple waveshaper modul :despair:
----------------------------------------------------------------------------------

The ULTIMATE (S)MS-911!?!?:
# 1 x External Signal Processor: Input level in + knob, Input level out 2x + knob, Range cv in + knob, range cv out 2x , Portamento cv in + knob, Portamento cv out 2x, Dist. cv in + knob, Dist 1x in Dist. 2x output + knob, Env 2x out, Trig 2x out, Hz/V 2x out

# 1 x VCO: Octave knob, Coarse knob , Fine knob, (hard + soft) sync input, FM in + knob, FM mod in + knob
Hz/V in, V/oct in, CV in 1 + knob , CV in 2 + knob, 8" cv in PWM + knob, 16" cv in PWM + knob
outputs: 16" sqr, saw, pulse, 8" sqr, saw, pulse, 4" sqr, saw output

# multiples: 4x 1 in 3out

# VCF 1: MS20 style: cv in Cutof + knob, cv in Resonance + knob, Input, Output; LPF, HPF, Bandpass, Notch
# VCF 2 + 3 MS-10 style: cv in Cutof + knob, cv in Resonance + knob, Input, Output; LPF, HPF, Bandpass, Notch
# VCF 4: cv in Cutoff + knob, cv in Resonance + knob. LPF/HPF switch on VCF 4. Input, output

# 2 x Active filter: cv in Tone + knob, in-output, (waveshapers/filters layerable???)

# 4 X lin. VCA: cv 1 + knob , cv 2 + knob , gate in, audio input + knob, 2x audio output + knobs
# 1 X cv mixer: voor 4x lin. vca's

# 2 x 4 input mixer: Level + output knobs, inputs , outputs.

# 2 x AR Envelope: cv in Attack +knob, cv in Release + knob, Trig in, re-trig in, output, 3 switch (slow/normal/fast)
# 3 x D Envelope: cv in Decay + knob, Trig in, re-trig in, output, 3 switch (slow/normal/fast)

# 2 X exp. VCA: cv in 1 + knob , cv in 2 + knob , gate in, audio input + knob, 2x audio output + knobs, cv out

I hope a more technical wiggler shall studie the schematics to conclude if the X-911 will house all the options?

So far are at least 5 person are serious into this project. Hopely we will reach 10 to start a small batch. :banana:
------------> Jaime Murray does Capua.... ------------------------------------------>

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Post by SMS303 » Thu Mar 25, 2010 12:28 am

Erik G. if you read this: Your schematic files are very usefull :tu:

The techn project so far:
The 2 technical guys do meet every monday and are studying the schematic files from Erik. At second meeting they discovered, Erik added buffers but nothing for grounding. It seems they have to solve this first, as far my techn. knowlegde goes.

Extra (pre-assambled) modules:
With my ultimate SMS911 specs idea, i was playing with the thought to add a cv-mixer from MMM. So he told by PM; Yes you can integrate without problems the CVM-1 into the system.

Realizing this project:
If the costs for the materials (= frontpanel, over 120 in-outputs, most of them incl. attuenator) are reasonable a small batch (10-15 or more) is upcoming!

The power for this project is ordering all at once, and have more discount.....
(even for international peeps by avoiding fee's, unless you won't take the risk)

So...... if you own a X911 and do like this project...
KEEP UPDATED BY THIS THREAD...

and my poor English :)
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lombrose
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Post by lombrose » Thu Mar 25, 2010 8:59 am

Oooops, I have one!!!


:bananaguitar:
:nana:
:banana:

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Post by SMS303 » Sat Mar 12, 2011 9:48 am

This project would be a long... very long term project...

You can find very good readable schematics via Rapidshare:
http://rapidshare.com/files/452186563/K ... _GREY_.pdf
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Post by Tim Stinchcombe » Sat Mar 12, 2011 10:07 am

SMS303 wrote:This project would be a long... very long term project...

You can find very good readable schematics via Rapidshare:
http://rapidshare.com/files/452186563/K ... _GREY_.pdf
:tu: Way, way better than either the previous pdf or jpegs I found off the net - thanks! Really must get around to firing my X-911 up one day...

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Post by SMS303 » Sat Mar 12, 2011 10:22 am

Tim Stinchcombe wrote::tu: Way, way better than either the previous pdf or jpegs I found off the net - thanks! Really must get around to firing my X-911 up one day...
Your welcome :tu:

These are the OTA based VCF schematics....
I haven't seen the Korg35 ic so far in the schematics...

Later when i'm at home i'll add the modification notes from Erik G., which are based on the Korg35 ic.

I was over-enthousiast about this project when i opened this topic..
But i'll keep this project in mind and will start probarly next year with it...
When i have more experiences by the Best of CGS/Serge projects :)

Edit: hittin' the 250th posts made me a Wiggler with Experience :nana:
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Post by Tim Stinchcombe » Sat Mar 12, 2011 10:51 am

SMS303 wrote:These are the OTA based VCF schematics....
I haven't seen the Korg35 ic so far in the schematics...
You get both! Sure on page 7, the Synthe VCF is based around the OTA filter, LM13600 IC8. But on page 6 there are three VCFs based around the same structure as the Korg35, only using discrete components: check out Q3-Q7; Q9-Q13; and Q15-Q19. :hyper:
Edit: hittin' the 250th posts made me a Wiggler with Experience :nana:
My second green goo birthday is very soon...like tomorrow :party:

Tim

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Post by Low-Gain » Sat Mar 12, 2011 12:24 pm

If you want, i can create a page on my website
to document your findings so it can be easily found.
PM me if you want.
My site is going under a large conversion over to wordpress at the moment,
but it's not difficult to toss together a simple page w/ the files, info etc,

This is great stuff!! it makes me regret selling my x-911 years ago.
I'll have to find another one.

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Post by SMS303 » Sat Mar 12, 2011 9:24 pm

Erik G's notes in zip:
http://rapidshare.com/files/452275180/Korg_MS911.zip
------------------------------------------------------------------------------------
Resonance control:
I don't have a schematic for it. But I can tell you that I have used exactly the same resonance control as in MS-20 version 2. The main filter in 911 uses the same filter as MS-20 ver. 2 and you can find the MS-20 schematics anywhere on the web. Just insert the extra OPamp, pot and diodes and you will have a full resonance control.
Good luck!
Erik/

MS20 Schematics:
http://rapidshare.com/files/452275031/K ... M13600.pdf
http://rapidshare.com/files/452275067/K ... matics.pdf

Parts:
324n - Quad Low-Power Op Amp
358 - Dual Op Amp
393 - Dual Comparator
4011 - Quad 2-Input NAND Gate
4013 - Dual D-Type Flip-Flop
4066 - Quad Bilateral Switch
4069 - Hex Inverter
4558 - Dual Op Amp
7815 - (Nec 14315) - Voltage regulator
CA3140E - MOSFET Inp./Bipolar Outp. Op Amp - (offset selected)
RC4200 - Analog Multiplier
TL071 - Low-Noise JFET Op Amp
LM13600N - Dual OTA
Last edited by SMS303 on Sat Mar 12, 2011 9:45 pm, edited 1 time in total.
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double post....

Post by SMS303 » Sat Mar 12, 2011 9:34 pm

double post .... :bang:
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Post by Low-Gain » Sat Mar 12, 2011 10:34 pm

I'll download this stuff tomorrow morning and get it up on my server and put together a simple information page.
From there we can up-date as more info is found.

I plan to have a section on my site for synth modification documentation so this will be perfect!

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Post by SMS303 » Sat Mar 12, 2011 10:39 pm

Low-Gain wrote:I'll download this stuff tomorrow morning and get it up on my server and put together a simple information page.
From there we can up-date as more info is found.

I plan to have a section on my site for synth modification documentation so this will be perfect!
Great! Don't forget mention Erik G.
He's the one who modified his X911 :)
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Post by Low-Gain » Sat Mar 12, 2011 10:55 pm

Absolutely!!!

:sb: :sb:

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Post by Reese P. Dubin » Mon Mar 14, 2011 12:44 pm

I got a 911 a few months back, and have a question.

Does the INSTRUMENT section have a MUCH higher volume than the SYNTHE section. mine is probably 2x as loud (at least) and makes mixing the sections nigh on impossible.

This has made it kind of difficult to figure out if anything else is not functioning properly.

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Post by maskull » Mon Mar 14, 2011 7:58 pm

Does anyone know the size of the X-911 PCB?

I'm trying to figure out if I can fit this in a 3U Eurorack case...it would be an insane amount of HP...

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Post by SMS303 » Mon Mar 14, 2011 8:22 pm

Havent opened the X911 and I dont know the exact dimensions of the pcb's. :despair:

I dont expect they will fit directly at the frontpanel with spacers. It seems pc board KM229 has almost same innersize as the X911, see page 10 of the schematics ;)

I think they will easily fit when maunted 90degrees at the back of the frontpanel. This will eat lot of backspace. A 19" four or 5U panel plus housing is imo considerable. :)
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Post by dougt » Mon Mar 14, 2011 10:12 pm

SMS303 wrote:This project would be a long... very long term project...

You can find very good readable schematics via Rapidshare:
http://rapidshare.com/files/452186563/K ... _GREY_.pdf
No longer available. :( Can someone who got it send it to me or re-post it?

Thanks,
Doug

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Post by Low-Gain » Mon Mar 14, 2011 11:23 pm

dougt wrote:
SMS303 wrote:This project would be a long... very long term project...

You can find very good readable schematics via Rapidshare:
http://rapidshare.com/files/452186563/K ... _GREY_.pdf
No longer available. :( Can someone who got it send it to me or re-post it?

Thanks,
Doug
I'll have it hosted on my website soon> Sorry been super swamped.

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Post by SMS303 » Mon Mar 14, 2011 11:34 pm

dougt wrote: No longer available. :( Can someone who got it send it to me or re-post it?
Thanks,
Doug
MS20:
http://rapidshare.com/files/452605261/K ... M13600.pdf

X911:
http://rapidshare.com/files/452605351/K ... _GREY_.pdf
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Post by jamb » Mon Nov 07, 2011 10:11 am

hey does anyone still have the eric g x-911 schematic?

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