The Groovesizer RED is a DIY 16-step sequencer and granular synth. REDIt’s based on the original Groovesizer mk1 Arduino project. It features 16 LEDs (one per step), 5 potentiometers, and 5 buttons, MIDI input and ouput on 5-pin DINs, MIDI sync in and out, and audio out (mono) on an 1/8″ jack. There are 32 user locations for saving patterns and patches. Up to 4 patterns can be chained together to create a 4 bar pattern. Note entry can be quantized to one of 12 pre-defined scales. Patterns can be triggered and transposed via MIDI. Notes can also be entered via an attached MIDI keyboard.

Here’s a video showing off the play modes of the Groovesizer RED.

This video demonstrates the 4 modes for the Groovesizer RED’s user banks.

This video demonstrates automation on the Groovesizer RED.

Features at a glance:


  • granular synth based on Auduino
  •  synth settings saved with pattern
  • Live Play mode (via MIDI keyboard)
  • automatable grain decay 1 (sounds similar to filter cutoff)


  • note entry for individual steps or groups of up to 4 steps at once
  • rests, ties, slides and accents for each step
  • pattern length from 1 – 16 steps
  • pattern retrigger
  • tap tempo
  • 6 play modes (forward, reverse, pendulum, random interval,  drunk, random)
  • pattern transpose (semitones or octaves)
  • adjustable note duration
  • swing/shuffle
  • MIDI in/out (note, clock sync, trigger)
  • MIDI note entry
  • MIDI transpose pattern
  • send automation via MIDI cc
  • note entry quantized to 12 preset or 4 user defined scales
  • 32 save locations arranged in 8 banks of 4 patterns
  • 4 play modes per bank (loop 1, loop 2, loop 4, random)