MIdrum 2 X2 S3

The drummachine of the Anushri by Mutable Instruments is great. Olivier Gillet later expanded on it with his Grids.
My MIdrum is the concept of these generative drums, translated into a compact midi-drummachine.

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

Compared to my original MIdrum, two things have changed:

  1. This second version is based on Grids (hence the 2).
    • Interpolate between 25 drumpatterns
    • 32nd note step resolution
  2. This version has 6 drum-channels (hence the X2).

Compared to the previous MIdrum2 X2 this one is smaller

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.

Left
This version has 6 drum-channels.
The 12 faders and pots control channel specific parameters in groups of 2.
The first fader sets the Density for channel 1 (BD), the pot above adds to that a random amount.
The second fader scales the velocity for this first channel. The pot above 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

Middle:
4bit turning switch to select* Midi channel: 1=1; A = 10; 0 = 16
Left switch:

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

Right Switch:

  1. Midi thru on**
  2. Midi thru off
  3. Midi thru off

Top Grey pushbutton: reads and *activates the switches above. It also sends CC#120 (All sound off).
Black pushbutton = Stop: MIDI sync: Stop
Red pushbutton = Start: MIDI sync: Start
Grey/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.

** Midi thru will try to merge incoming midi messages with the generated drums (and clock) and repeat them on the midi out. This will work for simple note on and off messages, but as soon as continous messages are received the internal midi-clock will suffer severely.

Right:
Right Pot = Groove: 12 o'clock: straight, turn counterclockwise for 16T, turn clockwise for 8T [updated every quarter note]
Left fader = X & Right fader = Y: select a position on the drummap. [updated every step]

Led: visual bar and beat indicator for your non-midi-syncable-bandmate: Bar=Red & Beat=Green

Control board (7 x 17 cm)

  • 12 Pots
  • 12 Faders (30 mm travel)
  • 1 duo-color led
  • 1 switch 4bit
  • 4 buttons
  • 2 slide switches
  • 2 Pots
  • 2 faders (45 mm travel)

Motherboard (9 x 17 cm)

  • 2x 4067 (beneath Control board)
  • 6n137
  • Arduino Nano V3.0
  • bridge rectifier
  • LM7805

The adapter input is standard guitar pedal format accepting anything about 9Vdc any polarity, it even functions at about 9Vac, just make sure the LM7805 doesn't get fingerburning hot (fingerwarming hot is ok).

Video

MIdrum 2 on YouTube

Code
MIdrum at Github

Please.

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.