MOD: Korg Monotribe Modification

[marmad]

Here's a video look at what causes the severe clicking and popping in the Monotribe, as well as a couple of things you can do to eliminate them.

BTW, I'm designing an internally-mounted board for the Monotribe which will include the following features:

Click/pop noise suppression caps shown in this video
Individual drum decay/gain circuitry I posted about previously
Amplified outputs for HH, snare, BD, and full rhythm section
Trigger outputs for HH, snare, and BD
1V/Oct CV Out (+4V range) w/adjustable offset
Gate Out (not Sync)
EG to Rhythm volume
EG/VCO2 select for VCA
3 new inputs to the VCF:

1) VCO2 - with following controls
a) LFO/Normal Range
b) Triangle/Square output
c) VCO1 CV on/off with +4 octaves tracking
d) Coarse/Fine Tune
e) Hard/Soft VCO1 Sync w/intensity
f) Volume

2) Sub-oscillator - with following controls
a) VCO1/VCO2 input
b) -1/-2 Oct select
c) Volume

3) Pulse width modulator - with following controls
a) VCO1/VCO2 input
b) VCO1/VCO2/EG modulation input
c) Inital pulse width
d) Modulation intensity
e) Volume

There will also be boards for the mounting of the switches/pots/jacks along the top/sides - although the control board can be used with your own placement of pots, etc.

The boards are being designed for 4 Monotribes belonging to a client, but there will be spares - so I'll post info here when finished. Anyone interested can pick up a set of the spare boards for a reasonable price.

[marmad]

I also came across a french forum with some good info on adding volume control to the individual SD,BD,HH. http://fr.audiofanzine.com/synthe-an...-kick,p.3.html

Interesting - but there is misinformation in the thread. For example, he writes "The small potentiometer on the Monotribe card manages the mix between synth and rhythm part." This is absolutely incorrect: the volume pot for the VCA comes before the mixer with the rhythm, so you can adjust the mix that way,

The potentiometer is to adjust the bias current of the differential amp of the VCA. All you will do by changing that is to reduce the overall volume of the synth while increasing the level of clicks and pops. Watch my video.

[marmad]

Here's a short video demonstrating the following features from my VCO2 mod for Monotribe: VCO2 control of VCA, VCO2 CV tracking, and soft/hard sync w/VCO1.

[playthatbeat]

@marmad - Your retro-fit board sounds like an excellent idea..

You are going to design the board for a short-run production? Please offer Your spares publicly, i know i want at least one! that's something i could not pass up.. The monotribe is such a fun machine, it FEELS like the TB303 of this generation.. I think You may be hitting upon the DEVILFISH mod for Monotribes with this hi hi..

As for the click issue, i'd been kinda used to it on notes, thinking about the most basic of kickdrum synths - a click with an LF boom, but now You shine such a bright light on it, it's the cause of the 'tripping' that just is not precise enough to be not irritating in loops involving kick and very subby bass. i was convinced this was down to my (usually excellent) master sequencer not being high enough resolution, and the usual overhead and lag from MIDI clock causing issues.. but, even if you just run a nice bass pattern from the tribe and sync it to something else that is running a nice pokey clicky-attack kickdrum, and You are working on something minimal, it's there, and it's infuriating...

[juicepatrol]

monotribe drum decay mod helping please

Noob here, I'm in the process of the drum decay mod and currently have only the hi hat done with a three way switch, one side with a resistor, other side is a non polar cap. On this forum I came across a very good set of instructions on using a log pot instead. The question I have is where is the location of the +5v on the PCB? I can see +3.3 but can't seem to find the+5. This may be fairly obvious but any help would be greatly appreciated.

[playthatbeat]

Where is this 5v mentioned Juicepatrol? From (without reading back) i remember only the sync pulse being 5v - gated ofc, in sync with the system clock.

Speaking of clocking - i tried to use mine at a session recently, syncing to some 90's gear, as You do, and it would NOT respond to incoming clock with the simple MIDI mod i had done. thinking it was borked, i left it as was. When i got home, i tested it again using my PC here (mbox2) and it was fine - syncing to the midi from nTrack. I thought that was that really - the simple mod was not up to syncing to oldschool 90's hardware.

BUT.. again the issue happened with the new midi to CV box i bought in, from http://www.edv-technik-ts.de/ - it was working fine on all functions EXCEPT sync. i could not get it to do some of the cool things like a gate per bar and SYNC 24.. BUT, it was due to some of the midi status settings in the master sequencer (still Voyetra Seq+ gold - banging since 1990!!) which i corrected.

The master sequencer was fine as a master clock source (NOT MTC - just midi sync) for 25+ years, all the gear that was connected synced fine, but it seems the NEW midi implementation, like in the monotribe and the MUC400 and MUC8xx from edv-technik require some tweaking at the clock master to get them running.

NOW, i can have sync 24 (and divisions), a START gate a STOP gate a RESET gate from my MUC, so i can control and reset all the step sequencers with a START of the midi sequencer, AND the monotribe syncs super tight.

Just while i am here, thought i would mention it - if Your monotribe will not START from your MIDI sequencer, mess with it's settings, it will work, it's just a bit odd when it comes to type of MIDI clock status, so it may or may not require CONTINUOUS status. I will be more specific when i am sitting in front of the SYNC page in the sequencer soon.

[Karg]

Clocking mod works very well!

Hi,

I applied marmad's mod to reduce the clicking and popping sounds and it really works miracles. It is just adding a capacitor and everything is gone now. Thanks a lot.
For everyone having problems finding the soldering points, I have published detailed photos on my blog.

, Karg

[playthatbeat]

Nice Karg, good pics and clear mission there..

I've made mine switchable, as i actually *like* the click for some things i do. yeh well, sometimes a good bit of rattle is fun, especially in minimal territory!

[Karg]

Nice Karg, good pics and clear mission there..

I've made mine switchable, as i actually *like* the click for some things i do. yeh well, sometimes a good bit of rattle is fun, especially in minimal territory!

Hey, thanks Actually, I made mine switchable as well. I am just way behind with my posts about the Monotribe. I added a µprocessor (Teensy) into mine, which takes care of MIDI and also MIDI over USB. The nice part of that is that I can use it to e.g. set individual MIDI channels, map all drum notes, implement a precise clock based on BPM, implement LFOs, and last but not least: switch the capacitor

[playthatbeat]

orite - the teensy USB project board looks like fun.. So what's the story there? I see You blogged about midification using it here: http://karg-music.blogspot.ie/2016/01/midification.html and specifically the monotribe here: http://karg-music.blogspot.ie/2015/0...tribe-fun.html - so You have taken this to the next level now?

Fine Blog BTW - i see we share time for the Alesis 3630 compressor also Man, Alesis were so Hit & miss in that period. They had TERRIBLE quality control. In fact, the only Alesis product i still own is that compressor and my circuit bent HR16, everything else had terrible build faults, including their high-end stuff, all of which i was an early adopter of. My 3630 is fine - no issues.. OK, it's no Aphex, but its worked fine since the 90's. I love it's hard sidechain and easy distortion Man it's a shitbox, but so what, sometimes You need a little shit in the chain