Cycle Instruments Intros Tetrachords 4-Track CV + MIDI Sequencer For Eurorack

Cycle instruments recently introduced Tetrachords, a CV and MIDI note sequencer for Eurorack systems.

In a departure from traditional XOX style sequencers, Tetrachords does not generate rhythms or clocks of its own. Rather, any trigger or gate source can be used to trigger each of the four tracks. Combined with the assignable CV IN MOD matrix, Tetrachords generates melodies and chords that are as straight or as ‘wonky’ as the CV signals being fed to it.

The module harnesses the musical concept of Tetrachords to build scales. On the front panel the eight notes of the scale are broken up into two groups of four. Two Tetrachords. The controls enable the harmonic relationship of the two groups of notes to be changed independently. In this way it is possible to create every scale and move smoothly between scales on the fly.

Their promo video, above, shows how users can control multiple tracks and move the tracks in musically related ways using simple gestures. The example also demonstrates the Tetrachords keyboard mode, which enables the interface to be used like a standard MIDI keyboard with the 8 large buttons corresponding to the 8 notes in the scale.

“Our goal with the Tetrachords was to create a device that enables the exploration of compositional ideas through intuitive gestures,” says Cycle Instruments co-founder Nick Lavers. “As users interact with the device, manipulating scales, chords, and the relationships between different voices, they begin to internalize the concepts of music theory that we used to build the module. All the theory is right there on the panel if you want it, but you can also just close your eyes and move your hands until you hear what sounds good.”


  • Tetrachords’ is a four-track, polyphonic sequencer that generates chords, arpeggios and melodies.
  • Note information is output via four CV outputs, 3.5mm MIDI jacks, USB C MIDI and i2C.
  • Rhythms are sent to the Tetrachords using the four trig inputs or via MIDI IN.
  • Nearly any parameter on the module can be modulated using the six assignable CV MOD inputs.
  • The device’s suite of connectivity means it can act as a bridge between a modular system and the rest of a studio.
  • The interface enables users to quickly and intuitively build chord progressions, basslines and melodies that can be musically manipulated using simple gestures.

Tetrachords is available now, in a limited run of 100 units, for $1200.00 AUD.

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