Monotribe midi mod


I was wondering, how difficult can be to make a midi in/out mod in the monotribe, with all the needed features, like the miditribe, but self made?
Anybody has experience with that and could help in this, or it is to difficult?

yeah, I’ve made and sold hundreds of them. What do you want to know

I was just about to say “ask Altitude”

so… I would like to know all, where should we start from? :smiley:
Ok, first, thanks.
Sorry to disappoint you, but I am new to diy. Maybe you have read my posts already but in case you did not: I will start soldering audio cables in one month, then I will build a nebulophone, then the shruthi. This is the project. The shruthi is actually here, waiting…
Well. I have this monotribe which I cannot use much without midi, especially for the syncing.

I have visited this blog hoping to find some step by step guide like the one for the shruthi.
But apparently it is made by an expert for experts.

I think it would be a bit heavy for you if you have to explain everything to me step by step, so I would rather ask you what do you suggest me to read or to watch, to learn some things I need to know before I can do this mod.
And eventually later you could give me some help with what I still did not understand.
Of course you can also guide me step by step if you want :smiley:

But first of all, how difficult is it?

How about MIDI for the Monotron Duo? Haven’t seen anything out there yet.

@ piscone: find somone who can code midi and knows assembler for the TI uC thats in that thing, game on. It uses barely half the chip and all the pins have pads routed out almost asking for it. Its the only montotron that has a uC to quanitize the CV from the strip so I was hoping that they secretly built in midi but alas, that is not the case, sending midi to the TTL inputs does nothing

@Mr53: can you read a schematic? The midi in/out on the monotribe is the simplest of the simple midi circuits. All you need is the right parts (all 7 of them) and some prototype board

nope sir.
I can’t, but I can learn.
:slight_smile: so, if you tell me that it’s not difficult, I’ll search about schematics.
I see that the miditribe has got lot of components on the board, while you talk of seven, and I see that also the mod of game boy genius is essential.
do they all do the same with same quality?
same kind of midi messages, no noise, ability to receive and forward midi clock without adding delay?

All the kits are the same thing. There is no “brilliant design” involved here, this is the exact same type of midi input circuit that is found on every device that has a midi input and output. The midi functionality is built into the OS of the monotribe not this mod and there is a header on the MT circuit board specifically for midi i/o.

AM charges $70 for $4 worth of parts, its ridiculous. The whole reason I got into that biz is i called bullshit on their kit on Muff’s and someone dared me to come up with something better (which i did at half the cost). I’ll clean up my schematic for clarity and post it here shortly, if you can solder parts on to protoboard, then you can build this thing.

You can see my prototype on the right side here:

and the final board that just plugs in on top of the header

Hmm, this got me intrigued, what’s the other PCB with the big SMT cap? Never took the time to read up on possible mods for the Monotribe.

Individual drums out?

Well, Altitude, what can I tell, thanks :slight_smile:
I find “midiot” rather provocative. And I like it. It is your domain?

"if you can solder parts on to protoboard, then you can build this thing."
well, I would say, if I cannot solder on a protoboard, I should try to resell my Shruthi kit :slight_smile:

Wonderful, I will then midify my monotribe myself. Which sounds a bit redundant and cacophonous but you got it.


@pichenettes correct. You should know :slight_smile: The level of the individual drums is way below line level and that board boosts them up to match the level of the main out

@Mr53rg10 then you should be good to go. I’ll get the BOM and schem up tonight. The only tricky thing is the 2mm pitch connector that plugs into the MT mainboard. You need the right part and the right terminals and the terminals need a special tool to crimp correctly. You dont NEED this tool to do it though, you can just solder to the smaller part and crimp the bigger part with a generic tool (that will make more sense once you see the terminals)

@Jojjelito there are a bunch, u can see all my decay mods there (with resistors and wires). I’ve been meaning to do the caveman “osc off” mod which just shorts the waveform select switch to ground. I wish there was a more elegant way to do that but it works and I know several ppl that have done it without issue. There is also a gate level shifter mod to bump the drum gate outs to 5v instead of 3.3v that I’ve done

Mmm, by chance, have you ever sold modded Monotribe in Ebay?
When I was still a DIY ignorant I’ve let go a couple or three of modded monotribes with added midi in (no out, if I remember well) and knobs for the decay of the drums, and something else…
It was the same guy who did them all. I do not remember if he was German or not.

Thanks for the help.

No, i’ve built some on commission but never sold any on ebay. I know there were a few people offering built ones there.

@ altitude
thank you!
knowledge dropped…thumbs up
since i´m too a noob in electronics, i am very gratefull for the pics.
my MonoTribe has been MIDI-fied by another person, but it´s only the MIDI input.
also the guy messed it up a little, so no jamming on battery anymore…
still i managed to do the individual outs and the mods on the BD, SD, HH as well
unfortunately the outs are quiet and somewhat noisy…
have to find out how to cut the individual outs from the main jack.

ok, here is the schematic:

The output header corresponds to:

Pin 5: Midi in pin 4
Pin 4: Midi in pin 5
Pin 3: Midi out pin 4
Pin 2: Midi out pin 2
Pin 1: Midi out pin 5

(most midi connectors have numbers for the pins)

The connector for the 6 pin header on the MT

The crimp terminals for above connector

The way I hooked up the midi connectors was to use a 3.5mm TRS jack and wire that to a TRS cable that was cut in half with a midi connector on one end and the TRS pin on the other. This makes it a lot easier to mount the sockets to the case where you dont need to drill big holes for a full size midi socket

My install manual


The cables are just cables, right? I mean, a trs to midi cable is not slower than a midi to midi, right?

I will have to spend a time to understand the schematics.
All those symbols and letters should suggest me which components I must buy?
Or is it missing a list of needed parts?

Cables are just cables, midi is glacially slow by todays standards so you could use a coat hanger and have the same result. Midi connectors only use two pins of the DIN5 anyway so there is no reason to use any with more wires. Look in my manual and you will exactly how I set it up using the TRS cables, you wont find a midi to TRS cable though, you have to make it. You can use regular midi connectors as well but just make sure you pick a good spot with clearance inside the case

Parts list is trivial:

1x 10K
1x 220R
1x 100R

1x 100n (same as the Shruthi, the little radial yellow ones marked “104”)


6N137 (you dont need the surfacemount one)


All these parts can be found in the shurthi control board BOM if you’re looking for specific part numbers.

>you have to make it
no problem, I am prepared, I am ordering cable and connectors in Thomann to make audio cables, so I practice soldering before destroying my Shruthi kit, and I also save some money.

>All these parts can be found in the shurthi control board BOM if you’re looking for specific part numbers.
VERY good, you are a genius.
I like this forum every day more.


So, I am about to order in Reichelt:
6N 137
X7R-2,5 100N
1N 4148
and a protoboard, the UP 931HP
Is all ok or the protoboard is better another?
Do I miss something else, apart for the trs or midi connectors?
Then there is the connector for the 6 pin header on the MT and the crimp terminals for above connector but I confess I am having a hard time in understanding what to do with them.
I still had no time to learn how to read a schematic, but as I am doing an order in Reichelt finally with all what I need to solder cables and shruthi, I want to order all now.