B.A.C.H. is a four-voice generative composition instrument designed for Eurorack systems and for controlling MIDI instruments.

Choose a compositional language, define its constraints, then listen as the form unfolds. A phrase can move between the voices of a canon, branch like an L-system, evolve through a cellular automaton or follow a chord progression. Repetition establishes points of reference. Transformations gradually renew the musical material.

Twelve languages are available: fugue, canon, probability, tintinnabuli, minimalist processes, cellular automata, L-systems, fractal sequences, pattern transformation, combinations of several engines, and two rhythm-oriented approaches: Groove and Groove Mix.

Eight controls shape the material, its memory, its development, its transformations, its density, its tension, the relationships between the voices and its performance. These parameters remain accessible while playing, and each has an attenuated CV input.

The four tracks provide Gate, Pitch and velocity signals, as well as MIDI notes on configurable channels. An optional 64-position harmonic progression can be used to follow a chord sequence. The Break function introduces temporary silences, suspensions, fragments and reconstructions.

B.A.C.H. can run from its internal clock, follow an external Clock signal or synchronise to MIDI clock. It stores 128 presets on an SD card. The musician composes the rule as much as the music that emerges from it.