Korg Monotribe modifications thread

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sixart
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Post by sixart » Thu Apr 27, 2017 2:35 pm

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
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Post by zaphod betamax » Tue May 23, 2017 12:41 pm

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???

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Post by shurikenyo » Sun Jun 04, 2017 7:24 am

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 :hmm:

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Post by zaphod betamax » Mon Jun 12, 2017 8:09 am

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.

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Post by zaphod betamax » Mon Jun 12, 2017 8:12 am

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 :hmm:

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CeeJay
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Post by CeeJay » Mon Jun 12, 2017 1:03 pm

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/buchsengehaeus ... 40728.html

And the matching crimp contacts or ready made crimped cables like this:
https://www.conrad.de/de/litze-gecrimpt ... 48475.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
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Post by zaphod betamax » Tue Jun 27, 2017 9:50 am

I've also been told a PS2 mouse contains the same connector.
Have not been able to confirm this.

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bitflip
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Post by bitflip » Wed Jun 28, 2017 8:51 pm

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
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Post by zaphod betamax » Thu Jun 29, 2017 11:48 am

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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syntherjack
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Post by syntherjack » Mon Nov 06, 2017 3:24 am

Hello,
I've read some Wigglers were looking for Korg Monotribe LFO output mod. I made it for my friend and documented here (waveform shots, no cats):

https://syntherjack.net/korg-monotribe-lfo-output/

The most important thing - the schematics. Use it for your own responsibility :)

Image

Hope you find it usefull,
Cheers
Jack
homepage :: syntherjack.net

zaphod betamax
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Post by zaphod betamax » Mon Nov 06, 2017 10:43 am

Not sure if this has been added: It is golden!

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Post by zaphod betamax » Thu Nov 23, 2017 10:42 am

Late to the party, but here is my 4 voice PolyTribe!
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Post by zaphod betamax » Thu Nov 23, 2017 6:09 pm

4 Monotribes playing Marriage of Figaro....
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bitflip
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Post by bitflip » Sat Nov 25, 2017 11:31 am

zaphod betamax wrote:Late to the party, but here is my 4 voice PolyTribe!
Literally woodshedding?! :hihi:

Sounds great, BTW!

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Post by Darkside » Tue Nov 28, 2017 4:29 am

Mine has been modified by a friend with the simple declicking solution and thus is now almost a new instrument. Before that it was short of impossible to record with it, but now it's a completely different story especially when controlling the Monotribe externally. Yes, at lower cutoff there are some thumps, but it's not that bad overall.

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thetaflux
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Post by thetaflux » Tue Dec 05, 2017 12:57 pm

Darkside wrote:Mine has been modified by a friend with the simple declicking solution and thus is now almost a new instrument. Before that it was short of impossible to record with it, but now it's a completely different story especially when controlling the Monotribe externally. Yes, at lower cutoff there are some thumps, but it's not that bad overall.
care to share how you de-clicked your MT?

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Post by Darkside » Fri Dec 08, 2017 8:21 am

Well, all the information about that mod comes from this very thread, so you just need to dig the depth of it. As I'm not all that knowledged in electronics myself and obviously don't want to give out any wrong data, I can say only, that the mod consists of only one cap and that's about it, not sure about the size though.

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vanianbulman
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Post by vanianbulman » Sat Dec 30, 2017 3:29 am

Vcs3 wrote:
Vcs3 wrote: Image
For personal use only, Monotribe MS20 style overlay in Illustrator format: https://www.dropbox.com/s/1v1hq7xub3zy0 ... 0_Final.ai

Enjoy!
Anyone have this file kicking around that wouldn't mind PMing me? I sent Vcs3 a message, but I'm not holding my breath that they'll be online any time soon.

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Re: Confirmed: VCO mute on Monotribe

Post by zaphod betamax » Wed Mar 07, 2018 10:19 am

Bump from the future.
The Black Wire is the Saw Waveform Out
The Red Wire is the Triangle Out
The Blue Wire is the Main Switch out to VCF
and not shown but the highest position of the switch
is the square wave out. This is the one I mute, as it is
easier to solder.


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.
:yay:
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

Image
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.

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Post by zaphod betamax » Fri Apr 06, 2018 9:00 am

Results on Experiment #23B: External ADSR control of Monotribe.

Feed CV from external Envelope via 10k resistor to wiper on Vcf cutoff.

Envelope=MS-20kit

Scene #1 EG1 with Attack/Release and positive going CV. Works great
Scene #2 EG2 Inverted with negative going CV. Works great.
Last edited by zaphod betamax on Fri Apr 06, 2018 9:14 am, edited 1 time in total.

zaphod betamax
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Post by zaphod betamax » Fri Apr 06, 2018 9:05 am

Any luck? I own 5, soon to be 6 Monotribes and I would like this overlay.
Thanks

vanianbulman wrote:
Vcs3 wrote:
Vcs3 wrote: Image
For personal use only, Monotribe MS20 style overlay in Illustrator format: https://www.dropbox.com/s/1v1hq7xub3zy0 ... 0_Final.ai

Enjoy!
Anyone have this file kicking around that wouldn't mind PMing me? I sent Vcs3 a message, but I'm not holding my breath that they'll be online any time soon.

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Post by zaphod betamax » Mon Apr 09, 2018 12:10 pm

an experiment.
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Post by zaphod betamax » Wed Jul 25, 2018 10:46 am


nicolas3141
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Post by nicolas3141 » Thu Aug 23, 2018 9:11 pm

This is an epic thread : )

I am quite keen to look at a more sophisticated declick option which leaves attack with a bit of a click, but completely declicks and dethumps the release. Has anyone done that? Should be possible with a couple of opamps forming an asymmetrical slew limiter between the envelope out and the vca in. Just wondering if anyone has tried anything similar before I start hacking my way in there.

Thanks

TMA-1
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Post by TMA-1 » Sun Oct 07, 2018 1:12 pm

Sort of a shot in the dark here...

I was recently trying to replace the ribbon with a longer one for more precise control of pitch and I seem to have fried something, I think the VCA. No idea what I could have done. I'll try to post a video later if anyone thinks they can help troubleshoot.

Symptoms: drums sound totally normal, no problems there whatsoever. However the synth voice is nearly inaudible (but it IS there, just whisper quiet). I also get very loud clicks whenever I trigger the synth with the ribbon. It's those clicks and the quietness of the VCO that leads me to believe the problem is with the VCA.

Edit: I should elaborate that when I say click, I don't mean the classic envelope attack click that we've been fighting with for years, I'm talking about a new click that is as loud as the bass drum or snare drum.

I did previously have the triangle wave mute mod installed on a switch, so I could run external audio through the filter. However I removed that while I was poking around this time replacing the ribbon.

Thanks all

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