We locked down our synth architecture this week, and decided to switch from a true 6-voiced polyphonic synthesizer to a paraphonic synthesizer. We determined that the io usage and complexity from 6 true analog voices was too complex and risky to implement, and after testing paraphonic synthesizers we determined that the sound was good enough. Basically, paraphonic synthesizers work by using a single global “gate” where the filter envelopes of each note are synchronized, and resets only after all notes are released. This is different than a true polyphonic instrument, but acceptable for playing chords and monophonic melodies
For hardware, this means we’re using one VCF chip, one i2s stereo DAC, and one additional DAC for controlling the parameters of the VCF chip. We may implement two voices in hardware to create a “duophonic” synthesizer, which would allow true stereo patches and a small level of polyphony.