Photo: Marsha Vdovin.

As they did with the monotron synthesizer, Korg has quietly released schematics for its the analog drum synthesis portion of its monotribe synth and step-sequencing rhythm machine. You just see the bits that make the drum sounds, but that’s the interesting and modifiable part.

In order to grab the download, you’ll need to fill out a form with your name and address, saying you acknowledge you’re voiding the warranty and that you won’t turn around and sue Korg. That address doesn’t get used for anything, though, so long as you uncheck the “newsletter” box. Once you do, you get a high-res PDF (low-res image above) with the schematics, marked public. (Liability I know is an important issue. You never know; you might swallow the drum circuits and then sue Korg for feeling ill afterwards. Or something. Ask a lawyer.)

As for the design itself, it’s a notably simple design by Hiroaki Nishijima, an elegantly-minimal set of analog circuits for producing sound. As such, it should be ripe for modification. In fact, the first thing I’d be inclined to do is, rather than void a monotribe’s warranty, simply breadboard this circuit, which would make for exceedingly easy variations on the same basic layout. You might even wind up with something else. (One nice touch in the design: look at how the noise source is cleverly – and necessarily – linked to hat and snare sounds.)

Mods have also worked with MIDI – a port is hidden on the board – but apparently with sometimes-disappointing timing results. More promising is the thought of new drum sounds, and even some breadboarded drum circuits outside the monotribe itself.

And that’s what I think is admirable about Korg’s approach: in the earlier days of sound and music electronics, publishing these kinds of schematics was the norm. As opposed to today’s litigious age, it was more or less assumed that straightforward ideas would be copied and modified. Korg hasn’t said they’re encouraging that kind of behavior, but by releasing the schematics, they at least acknowledge that they’re unafraid of that potential scenario. The point is, you wouldn’t come up with a cloned monotribe – you’d simply learn something about analog drum synthesis, then move on to something that’d be quite different. Korg remains the company with the wherewithal to produce the thing en masse, anyway. It’s not open source hardware, mind, so there’s a gray area as far as your ability to use the circuit, but that shouldn’t stop you from wiring this up and learning from it.

Ultimately, my guess is we’ll hear some new drum sounds out of this, and that’s exciting.

Find the schematics at:

More on modifying monotribe:

An extensive, extensive post on MIDI modifications – how to do it, physically and electronically, as well as some of the limitations (which in turn partly explain why this didn’t ship with MIDI):
Monotribe, MIDI and me [Game Boy musician nitro2k01’s blog]

Video from above:

And one post on drum mods (I expect there are others, if you wish to share in comments):
MONOTRIBE drum mod and peek inside

In the interest of fairness, Chris Randall posted what I thought was a thought-provoking review of the monotribe. Keeping in mind Chris was apparently a great fan of the simpler, cheaper, smaller monotron synth – and produced an album with it / see link at bottom – his review of the monotribe and its bare-bones analog drums was pretty brutal.

See his original thoughts:
Monotribe Mini-Review…

…followed by some criticism of the monotribe in, oddly enough, an iOS-themed story:

Chris isn’t one to mince words or be especially diplomatic, but it’s worth reading what he has to say. He also predicts I’ll like … something just like this story. But it’s worth considering all sides of this little box. And despite what Chris says about my own perspective, I still believe for real modification, open source hardware is best – not that all hardware need be open source, but rather that for hardware you want people to modify, the open source license is a useful tool. I also think that it’s okay to just use gear and not always modify it; playing instruments is great, too, speaking even personally. That said, I still think Korg releasing schematics is a big deal, and I’m enjoying getting inside this particular design. And for the record, Chris still put some monotribe sounds into his music.

See also:
Electronic Sounds and Satisfying Limits: Chris Randall Talks About Making Capacitor, Resistor EPs

  • awesome.

  • Lematt

    Nice ! Now, Korg, bring back the real big analog synth !!!! MS20 with presets !

  • Nice.
    I've been triggering mine with just a piezo on my kick drum;

  • But that's just the rhythm section… Would've been nice if they had released schematics for the oscillator and filter etc. But since these very points are marked on the board, I'm guessing that they already decided beforehand what to release and not, unless the omission of the other things is an oversight. monomodder has already documented these points. Fairly simple: Just *** decay to ground through a potentiometer or resistor.

    What strikes me with the noise part of the schematic is how simple the "VCA" is. And when I see this, I understand why there's so much noise bleed-through. They just rely on the transistor to be conductive when you put a DC current through it. Elegant in all its simplicity, but imperfect.

    And likewise, the BD/SD frame circuit is simply a resonant filter that trigger with a click. No surprises there.

    I'm planning to reverse engineer more of the design, for example to see if you can do something about that horrible click that happens when you release a note. However, I won't be able to do that until at least two weeks from now, but stay tuned.

  • Take a step back.  Is it not a little funny that, in a world of endless banks of samples, people feel the need to mod the monotribe?  My thought is: If you really wanted more flexible drum sounds… maybe this isn't the device for you.  Its appeal lies in its simplicity alone.

    And the fun of making crazy patterns with the oscillator, of course.

    – c

  • Chad: Simplicity, sure, but also hackability. Monotron and now to some degree 'tribe was marketed as a hackable device. I think it's nice if you want to tinker around with electronics but not build something from scratch.

  • Peter Kirn

    @nitro2k01/@Chad: I look at it a little differently. Basically, you've got a simple circuit here that you can learn from and modify. The primary reason to do so would be to learn something, to experience the way in which this circuit produces a sound. There's no musical reason you need this particular circuit, no. That said, there's also no reason you need to look at this schematic and mod the monotribe; you could just as easily lay it out on a breadboard, so … while I'm sure KORG isn't going to say this … you don't actually need a monotribe for this schematic to be useful.
    People are doing interesting mods, of course, and then I think it's just convenient that you have the housing and other bits there for you.
    The oscillator and filter section are identical to the monotron as far as I know, so you can just refer back to those schematics for that section. 
    Everything else is just going to be on the microcontroller. I can draw you a schematic of that. It'd look like this:
    So that's why those bits weren't released. Not much point. 😉 And anyway, the analog bits are plenty interesting, so this is more than enough to play around with.

    (there's a reason why we release *source code* on the MeeBlip and not just a schematic … you have to know what's going on inside the black box of the microcontroller!)

  • Aaron

    Korg kicks ass and has a good set of balls on them for doing this sort of thing with their products. It shows they know their market pretty well. It also gives hope to the idea that they'll do some larger analogue products.

  • Elbas Basslee

    NICE!!! I'm really starting to feel a 'Bromance' between Korg and I. So far I've done the Midi mod and am EXTREMELY pleased with the results (Haven't stopped the acidic basslines for days), but because I use a Distortion pedal on the output for the synth, I haven't really been able to use the drums unless I multitrack. This weekends project is the Drum Output Mod to provide for a separate drum mix. Oh yeah, and the MonotribeKaossPad3 combo is pure villany!!! Ready to rave with only 2 boxes?? Yep…

  • Peter: Sort of what I wanted to say but didn't have time. No matter how you use it, the monotribe is meant to be inspiring in one way or the other.

    Lee de la Bass, the Electric Bass: Hope I'll hear the result of that later…

  • I think this is good, because the drum section is the weaker side of the monotribe compared to its synth section. While it would be nice to add further control to the synth & filter (and cleaner input/output stages), the drum sounds are lackluster and the sequencing rather humdrum. So now there's potential to tap into the drum section, beef it up and add more control for variation in the rhythm..and possibly separate outputs! Perfect!

  • strunkdts

    one again Korg prove theyre the leaders and the cool guys of the big three.

    Now, if only they would release a super version of the ESX with 8 outs, analog synth, multiple rows of step sequencer and gigs memory.

    Oooooh, baby!

  • greg

    Open Source? Puh-leeze. There is nothing interesting in the licensing of the monotribe's design, and the proud "all rights reserved" and legal release to get the schematic confirms that doubt.

    When people make instruments sans planned obsolescence, they call it a "service manual," and those come out (quietly) a few weeks after the product's release, too. No shortage of those.
    Cheers on Nitro for the midi.

  • James Grahame

    Greg: We're in a modern Dark Age where things like service manuals are rare. Korg's release of the schematic indicates that they're willing to share their designs with the DIY community. It benefits us, because we can mod their products and it benefits the company through increased sales.

    The legal release to get the schematic is a bit daft, because I most certainly didn't have to agree to any legalese to get a copy of the pdf, and one could easily circumvent copyright by making slight design changes and recreating the schematic.

  • greg, James: I don't think their worry is copyright, but warranties. "Anyone" could reverse engineer the noise circuit and more, and even so the schematic is copyright Korg with or without a slew of legalese.

    Software companies are known for putting a bunch of legalese in the end use license to force the user to only use the software under certain conditions, but even so these license agreements have been thrown out by courts as invalid; it's not reasonable that the user should read all that text. And again, this is a case of simple copyright, so you don't need that.

    What they're actually worried about is warranty and legal responsibility. The text in both the schematic and on the download page is a hints this. If they didn't put that note there, someone might claim that Korg should repait his monotribe after his failed modification. It was sanctioned by Korg, after all. Or worse, someone's house burns down because of a failed modification. (Extreme, but the principle holds true.) If there was no agreement/warning text, someone might claim that Korg is liable. You need to take these precautions as a big company.

    And that says more about the U.S. legal system than it does about Korg.

  • Also, why do all the comments, including mine, posted today 9/8 or 9/9 (depending on your time zone) say Sep 2? I think we haz a bug!

  • Preftempopkek

    здравствуйте. меня маг попросил, когда будет результат от его работы (я заказывала приворот), оставить отзыв о его работе. лучше всего на форуме моего города , района, чтобы знали что в интернете есть действительно сильный и настоящий маг. с привеликим удовольствием это делаю. я обращалась к магу александру цынь. спасибо вам александр все произошло как вы и говорили , еще раз спасибо.
    альбина, россия, СПб

  • I have one of these, I really like it for the money and I’m impressed that Korg is encouraging mods. Got the schematics and was poking around the Google for more info.

  • I have one of these, I really like it for the money and I’m impressed that Korg is encouraging mods. Got the schematics and was poking around the Google for more info.

  • Adam

    The sounds these things can produce are endless. Combined with some effects, you can make any kind of synth- keyboard- guitar- theremin- bass sound you can imagine. I’ve been messing around with the monotribe, kaoss pad quad, and a multitrack recorder for about a year now. It’s always fun and direct.

    Check out some of the things I’ve come up with on the monotribe.

  • Adam

    The sounds these things can produce are endless. Combined with some effects, you can make any kind of synth- keyboard- guitar- theremin- bass sound you can imagine. I’ve been messing around with the monotribe, kaoss pad quad, and a multitrack recorder for about a year now. It’s always fun and direct.

    Check out some of the things I’ve come up with on the monotribe.