Korg Monotribe modifications thread

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DBM
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Post by DBM » Fri Aug 05, 2011 11:33 pm

Sir Ruff wrote:
Veqtor wrote:[video][/video]

I got to see the "holy fuck" moment first hand! :tu:
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

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nitro2k01
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Post by nitro2k01 » Sat Aug 06, 2011 12:45 am

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:
Image

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.
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Post by DGTom » Sat Aug 06, 2011 1:15 am

:omg:

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 :omg:

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Post by nitro2k01 » Sat Aug 06, 2011 1:50 am

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.
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Post by DGTom » Sat Aug 06, 2011 2:43 am

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 :D

An analog Reset in & access to this double speed clock + drum section clock in would be awesome!

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Post by aksen » Sat Aug 06, 2011 2:49 am

:omg: :deadbanana:

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...

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Post by bartleby » Sat Aug 06, 2011 3:10 am

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?

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Post by Veqtor » Sat Aug 06, 2011 3:31 am

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...

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Post by nitro2k01 » Sat Aug 06, 2011 3:33 am

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.
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Post by bartleby » Sat Aug 06, 2011 3:57 am

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? :)
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.
Last edited by bartleby on Sat Aug 06, 2011 4:02 am, edited 1 time in total.

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Post by darenager » Sat Aug 06, 2011 5:42 am

DGTom - You can sync a stock monotribe to the Leploop using either of the Leploop gate outputs - works great :tu:

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Post by DGTom » Sat Aug 06, 2011 6:48 am

darenager wrote:DGTom - You can sync a stock monotribe to the Leploop using either of the Leploop gate outputs - works great :tu:
Thats what makes it so appealing :D

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

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Post by Veqtor » Sat Aug 06, 2011 11:07 am

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?

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Post by dykehouse » Sat Aug 06, 2011 1:03 pm

Some unbelievable modifications really opening this bad boy up...nice work!

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Post by DBM » Sun Aug 07, 2011 2:18 am

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 ?
Last edited by DBM on Sun Aug 07, 2011 2:23 am, edited 2 times in total.

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Post by DBM » Sun Aug 07, 2011 2:18 am

Btw thanks for your work here I love the sound of it , I just prefer to play with keys . Keep up the great work !

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Post by DBM » Sun Aug 07, 2011 5:26 pm

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 :doh:

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Post by nitro2k01 » Sun Aug 07, 2011 5:51 pm

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.
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Post by bcmonke » Sun Aug 07, 2011 5:57 pm

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

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Post by nitro2k01 » Sun Aug 07, 2011 6:13 pm

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.
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Post by DBM » Sun Aug 07, 2011 6:31 pm

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 :)
Last edited by DBM on Sun Aug 07, 2011 6:33 pm, edited 1 time in total.

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Post by bcmonke » Sun Aug 07, 2011 6:32 pm

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.

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Post by DBM » Wed Aug 10, 2011 9:31 am

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 ?

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Post by nitro2k01 » Wed Aug 10, 2011 9:50 am

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
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Post by DBM » Wed Aug 10, 2011 9:56 am

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 .

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