MIdrum (english)

The drummachine of the Anushri is great. Grids took the concept even further. 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.

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.

Faders X and Y select a point on a drummap, using this position a drumpattern is generated. Each density fader adjust the density of f.e. bassdrums outputted. Using pot R1 you can add a bit of random BD density to your loop.
The Velocity faders scale the output velocity and pot N1 selects the midi-note-number.

Density BD: amount of BD each bar (0-100% positive)
R1 BD: adds random a bit of Density BD (0-100% positive)
Velocity BD: velocity scaled (0-125% give or take)
N1 BD: midi noot number
Same for SD and HH.
N2 SD: midi noot nummer
N3 HH: midi noot nummer
Every control Left is updated every 16th note.

C: 4bit turning switch to select* Midi channel: 1=1; A = 10; 0 = 16
Dips: Dipswitches*:

  1. Led tempo [off / on]
  2. Midi thru [off / on]**
  3. Midi sync int messages(Clock+Start+Stop) thru to Midi-out [off / on]
  4. Midi sync [ext / int]

Dip: reads and *activates C and Dips. It also sends CC#120 (All sound off).
Stop: MIDI sync: Stop
Start: MIDI sync: Start
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 continuous messages are received the internal midi-clock will suffer severely.

ModW: Modwheel. [updated 48 times per quarter note]
Groove: 12 o'clock: straight, turn counterclockwise for 16T, turn clockwise for 8T [updated every quarter note]
X & Y: select a position on the drummap (Anushri-style). [updated every step]

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

Control board (8 x 10 cm)

  • 6 Pots
  • 6 Faders
  • 1 Rotary switch 4bit
  • 1 Dipswitch 4bit
  • 4 buttons
  • 2 Pots
  • 2 faders

Both the rotary switch and the dipswitch are connected to the arduino using only 1 analog input each. This is done by use of the (smd) resistors. See the code for details on the values.

Motherboard (10 x 16 cm)

  • 4067 (beneath Control board)
  • 6n137
  • 1 two color led
  • 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).

MIdrum on YouTube

Prototype Synthforum meeting
MIdrum prototype (Dutch)

Mutable Instruments forum
Synthforum (Dutch)

MIdrum at Github

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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.