Tonic is an additive interval pitch sequencer that turns triggers into melodies.

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Tonic is an additive interval pitch sequencer that turns triggers into melodies.

Tonic is a clever but uncomplicated module which opens up new possibilities in a modular system. It’s a new concept and very different from a step sequencer, allowing a new way of thinking about musical sequences and melodies.

In a slim 6HP format it offers one adjustable and five fixed intervals. Each interval has a trigger input and manual trigger button. Freely combine intervals for more than four octaves chromatic range.

Demonstration Video

Instruction video


Tonic works by adding intervals. From top to bottom, the intervals are:

  • Adjustable -6 to +12 semitones
  • +16 semitones
  • +8 semitones
  • +4 semitones
  • +2 semitones
  • -1 semitone

The bottom interval is negative, the middle four are positive. The top, adjustable interval has a range from minus one half octave at fully counter-clockwise, to plus one octave at fully clockwise, with zero in the middle.

The default tuning gives you wholetone steps: +2, +4, +8 and +16 semitones. The bottom, negative interval drops the pitch by a semitone. By adding them up this provides a basic range of 32 semitones, not counting the adjustable interval.

Custom Tunings
Tonic is entirely analog, and the fixed intervals can be tuned with the five 23-turn precision trimpots on the back of the module.
The tunable range for each interval is, from top to bottom:

  • 0V to 2.15V
  • 0V to 2.15V
  • 0V to 1.55V
  • 0V to 1.55V
  • -1.55V to 0V

1V equals one octave by Eurorack convention. Tonic can just as easily be tuned to Equal Temperament, Just Intonation, Meantone, or microtonally.



  • Width: 6HP / 30.00mm
  • Height: 3U / 128.50mm
  • Depth: 25mm
  • Weight: 58g


  • 10-pin Doepfer/Eurorack
  • Reverse voltage protected
  • +12v: < 85mA
  • -12v: < 15mA


  • Outputs: <= 1k Ohm
  • Inputs: >= 100k Ohm

Open Hardware

Open Hardware Logo
Tonic is Open Hardware, published under the Gnu GPL.

The schematics and BOM are publicly available on GitHub.
Please send your patches to us as pull requests and bug reports as issues on GitHub.


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