MIdrum UC33

A bigger MIdrum, based on a UC-33e by Evolution (M-Audio)

MIdrum is a rythmmachine outputting midi. A good explanation of the generative principle kan be found in the Manual of Grids.

Just to be absolutely clear: the idea of generative eigendrums is not mine.
I just thankfully use ideas and code by Olivier Gillet of Mutable Instruments.

This version has 6 drum-channels.
The fader sets the Density for a channel (BD), the pot above adds to that a random amount.
The middle row pot scales the velocity for the channel. The top pot selects the midi note number.

The first 3 channels are the same as those in Grids.
The second 3 channels are derived from the first 3 by calculating their density based on the density of the first 3:

  • Density 4 = ( Density 1 + Density 2 ) / 2
  • Density 5 = ( Density 1 + Density 3 ) / 2
  • Density 6 = ( Density 2 + Density 3 ) / 2

Led: visual bar and beat indicator for your non-midi-syncable-bandmate: Bar=Red & Beat=Green
Right Pot = Groove: 12 o'clock: straight, turn counterclockwise for 16T, turn clockwise for 8T [updated every quarter note]
Fader7 = X & Fader8 = Y: select a position on the drummap. [updated every step]
Fader9 = Modwheel

Top left red pushbutton: reads and activates the switches at the back. It also sends CC#120 (All sound off).
Top white pushbutton = Stop: MIDI sync: Stop
Bottom red pushbutton = Start: MIDI sync: Start
Bottom right white pushbutton = Tap: after tapping 4 times a new taptime is calculated. This new taptime will only be implemented after pressing Start once. So, while the MIdrum is running or not, you can tap 4 times to get the new tempo and press play once to update this new tempo.

4bit switch to select* Midi channel: 1=1; A = 10; 0 = 16
Power switch selects sync:

  1. Sync Ext
  2. Sync Int + Midi Clock messages(Clock+Start+Stop)
  3. Sync Int

I've kept most of the controls board of the uc33 including the 4 onboard cd4051.

The adapter input is standard guitar pedal format accepting anything about 9Vdc any polarity, it even functions at about 9Vac.

Code (similar)
MIdrum at Github


This page is presented for my personal enjoyment. I hope this page will also be an inspiration for diy-ers all over the world. This page is not meant to be a manual, so please don't contact me for guidance or support.
Thank you and enjoy.