Donnerstag, 28. Juli 2011

MONOMOD #2 --- Separating the drums from the mix

When looking closely at the main PCB you will find 4 soldering points that say BD Out, SD Frame Out, SD Out, HH Out. These are outputs of the different drum parts. The important thing on this is that they are not controlled by the drums volume knob. So if you turn that down you will still have signals of all 3 drum parts when you use these output connections.

One thing to mention here is that the different drum part outputs are not perfectly clean. That means that you hear a very small portion of the BD and the SD when connecting to the HH Output. And vice versa. But that did not bother me, because you can separate the drum section from the synth and add different effects on both. And thats a great benefit. Also you can mix the drums together in the way you want to have them mixed.

I've combined SD Frame and SD Noise so that i have 3 different outputs BD, SD, HH. I also connected the 3 output jacks in a special way.

  • If only the BD jack is used and the others are not plugged in, you get the complete drums mix on the DB jack.
  • If you plug into the SD jack the SD and HH signal is removed from the BD jack and you have one connection with only BD and one with SD and HH mixed together.
  • If you plug into HH the HH signal is disconnected from the SD jack and you can have BD/SD mix and HH separated.
  • If you plug in all three, you have BD, SD and HH separated from each other.
The main intentin on this was to get the most flexibility. So you can just get the drums mix separated form the synth, if you maybe have only two channels free on a mixing desk or your recording equipment, or you can have all four parts of the monotribe separated from each other and go ahead with an advanced mix.

I added a 3K resistor to each ouput channel. The connection of the jacks and the soldering points is straight forward.

Everything you do to your monotribe is at your own risk! Don't blame me if you destroy your gear!


  1. What's the purpose of adding the 3Kohm resistor to the output channels? It should be on the + wire and not the ground, correct?

    Cheers for your good work, one of the very few blogs that provides hands-on information for modding the monotribe... have you done any work on the Monotron? :)

  2. It's alway a good idea to add a resistor to the output of an audio signal so you don't ever have the chance to shorten that output with wahtever you plug into it. 3k worked nice for me. The Resistors I have wired to + wire, right.

    I have never done any mods to some other music instrument before. So these are the first one's. But I'm thinking about getting a Monotron and modding that thing to add it to my rig.

  3. Any ideas on how to overcome the Signal to Noise issues with this mod? Having to increase gain on this channel to compensate, which is introducing a lot of line noise. Also, have you noticed the BD has a bit more 'pop' on the attack coming out from this line?

  4. Hi, I like the idea to independently use BD, SD and HH and be able to unite those channels the way you described! Could you give me a hint how you did it? :)

    btw, great work - I also like your recordings!!

  5. @DocWieler: I must admit that i have no signal to noise issues. so at that point i can't help you out. The pop is more at that point, right. I've no idea why. The point is that the BD all in all sounds not very great to me. It's very deep and has a lot of attack and I don't like that a lot.

    @PS: You have to use jacks that support turning one signal off when you plug something in. So you take 3 jacks and put the HH on the first one and at the same time connect the HH in from the jack to the jack switch that will brek the connection when you plug something in. That you connect to the SD jack and so on. This way you can combine your separate outputs in a flexible way.

  6. Hi again, Klaus. I am building an external box with all your mods and midi in capabilities (just to give to everything the right space) and I am using instead of your configuration, a rig of 4 rotary switches that can route every drum out to any of the output jacks for maximum flexibility). I am trying also to have a "mute" option so that the selected drum channel won't return in the original output signal flow. any idea on how can I do it? Is it safe to shorten directly to the ground? should I put a resistor between the line and the ground? any other suggestions?
    about the punchier sound, I understand that the resistors are useful, but they act as a high-pass filter, so that's the reason for your brighter sound in bass freqs.
    my question (connected to my previous one) is: if the line goes directly to the ground, can it provoke a damage to the circuit? or the purpose of the resistor is just to prevent issues with external circuits(e.g. power amps, leeking mixers etc.)?
    finally, i used a log pot for the decay mod. but it acts as you depicted to be a lin pot. the only problem is that i measured values in centered pot position, and it gives different values. this means that my pot is a real log pot, not a lin one. could you please check yours? I know that there are different labels around the world (a,b,c), so if you used a lin pot, it would be the case co correct your instructions. btw,i will try with lin pots,and i'll let you know.
    thanks for your attention

  7. please check the pot. for me it worked a 2.2k LIN pot (more precise in the entire range) and a resistor of 270 ohm (longer -non endless-decay.if i want back the original sound, I just disconnect the box)

  8. With the log pot it's the thing that you can use it in two ways. so you should try both ways and you will hear a difference! the cool thing about using log pots is that your range of the decay is far more controllable than with a lin pot.

    You should never shorten something directly to the ground if you have no schematic and don't know what you're exactly doing. You always should use a resistor instead. Otherwise the circuit may get damaged. I think a 1k resistor should be a good choice.

    For the brighter sound: I don't have a brighter sound, or maybe i did not listen good enough. Typically a high pass filter would need a capacitor in line with the drum output. If there is one in the schematic this will work as a hp filter. That's right! But i don't think it is. The very low end of the bassdrum is still there. Maybe you should connect your monotribe to a nice bass speaker and give it another try.

  9. How do I simply connect a jack to each drum sound?

    I tried connecting the drum sound outs (for example bd)
    to the "ground" pin and got no signal.
    I tried connecting it to the battery "+" and got
    terrible noise.

    Is adding a resistor enough, or where should I solder?

    Thank you for helping me with an advide!

  10. Hello,

    were do you add the 3k resistor? Inline between the mod point on the board and the jack or somewhere between signal and ground? I dont understand that.

  11. Hey,

    it's between the mod point on the board and the jack pin.

  12. If I'm trying to combine all drum sounds (BD, HH and SD Frame + Noise) into one 1/4 output, could I simply place a 3K resistor between each 'Out' and the 1/4 Audio Jack?

    BD Out---------3K--*
    HH Out---------3K--* 1/4 Audio Jack out
    SD Noise Out---3k--*
    SD Frame Out---3k--*

    -or should I connect all 'Out's to one single 3K resistor and then to the audio out?

    BD Out-----------*
    HH Out-----------* 1/4 Audio Jack out
    SD Noise Out-----*
    SD Frame Out-----*

  13. Hey.

    I wouldn't reccomend you to connect all outs to one 3K Resistor (version 2). This might lead to a sound influence between each of the 4 outputs. It is better to connect every out with a 3K Resistor (version 1). While the resistors will be placed in parallel the impedance on your 1/4 audio jack output will be at 750 Ohm. You should make sure to protect your audio gear that you will plug into that jack properly. So it's always a good advice to check the impedance reqirements of your following audio gear (mixing desk, ...). If you want to make sure that your following audio gear won't get damaged you should add another 1K Resistor between the sum of the 3 outputs (after the 3K Resistors) and the 1/4 jack.

    So good luck with your DIY. Hope that I could help you with your mod. If you screw up your stuff, I'm not responsible.


  14. How exactly did you figure the sum of the resistors to be 750 Ohms?
    (going by the formula I usually use to add resistors in parallel I arrive at a sum of 1K)

    In theory, if I were to add a 2.25K resistor(in series) after the sum of the three outputs--the output impedance of the audio jack would be at 3k, correct?
    Here's a drawing I made:

    Thanks for your guidance Ed!
    I'll do some research on the line mixer I'll be running it into--
    and no worries, I assume full responsibility for my modding actions.


  15. Dieser Kommentar wurde vom Autor entfernt.

  16. very very interesting one output for all drum sounds
    i put in my early todo list :>

    thanks ed.klaus and lightwolf

  17. @lightwolf:

    There is a very nice online calculator that can handle up to 10 resistor values in parallel.

    That's correct. If you add 2.25K in series you are at 3K.

  18. Would it be possible to post an image or schematic? It seems easy enough, but I love my monotribe and want to be sure before I begin modding.

  19. Is it possible to just jump the BD out to the headphone jack and have all three drum sounds coming out with out an resistors?

  20. BD 1k, SDF 2.2k, SDN 22k, HH 2.2k resistors on the outputs, combine SDF and SDN to a single output, or double the values to 2.2k, 4.7k, 47k, 4.7k. Is the SDNz really hot? This should attenuate it.

  21. Hi Ed, thank you for publishing all these mods and tricks. I'm going to do this mod, too. But I'm asking myself: Do you know of a way to mute the internal BD when something is plugged into the BD out?

  22. Hi,

    the only way I know of, is to mute all the drums from the main mix. To Just mute the BD out of the mix, I don't know a solution. Sorry.

  23. Hi Klaus, I just got one of these and would be very keen to do this mod. Could you email me some instructions to, and if you have any progress photo's those could be helpful too. I have a miditribe kit on the way and would like to do thius while I have the unit opened up

    Many thanks


  24. Hi Ed,

    I am up to modding the individual outs on my monotribe (after doing MIDI IO successfully, and thankfully!). Your information has helped me greatly in understanding basic electronics again.

    I am looking to do the 4 outs to one output as Lightwolf above has mentioned -

    Please help with the following calculation: In light of the Korg Schematics and resistors directly after the "Out" pads listed as 22K, 220K, 22K, 10K would lead to a total of 5.1163k then I should connect to a 1.2k resistor to lower the final output to 100ohm line level?

    I hope that makes sense and I hope your still playing with the monotribe!

    Thanks Ed - Good Work and Thanks for Sharing!