Chebysynth

Chebysynth is a 16-note polyphonic MIDI synthesizer for Voltage Modular which uses additive synthesis, adding nine harmonics to a base frequency at different levels, to generate a range of timbres.

In addition to static harmonic volume control, represented by the traditional row of sliders, the synth has two envelope generators, which generate the usual Attack-Decay-Sustain-Release (ADSR) envelope curves. The first controls the amplitude of each note played. The second controls a boost or cut applied to each harmonic in the series, enabling the timbre of the note to be modulated by the envelope while it is playing.

Each note played can be voiced by up to eight harmonic oscillators, which may be varied slightly in pitch and stereo position creating a rich and dynamic sound. The “pitch spread” and “stereo spread” knobs evenly distribute a range of variation across the voices, while the “pitch drift” knob controls the amount of random pitch variation applied to each voice. A vibrato effect with controllable speed and depth is applied equally to all voices.

For more distorted or metallic tones, similar to those produced by FM synthesis, a “feedback” knob controls the amount of the harmonic-enriched signal produced by each oscillator that is fed back into the fundamental tone from which the harmonics are generated (using Chebyshev polynomials, as in Vulpus Labs’s popular Chebz oscillator).

The MIDI mod wheel is assignable to either the feedback amount, the vibrato depth, or the amount of harmonic modulation applied by the harmonic envelope.