Overview
pd-101 is a recreation of Casio's CZ series of phase distortion synths from the mid-80s. The CZ never had a filter. It shaped sound by bending how it read through a sine wave, which gave it a bright, glassy, slightly hollow tone that's hard to get any other way.
We didn't want something "CZ-inspired". We wanted it to behave like the real thing. The envelopes, vibrato, key follow, ring mod and noise were all checked against a real CZ-1, and where the hardware does something odd, pd-101 does it too. Noise is pitch-jittered, not white. Envelope rates are slopes, not times. Vibrato is shared across voices the way the original does it.
It also loads real CZ patches. The factory bank was decoded straight from original CZ sysex dumps, so the brass, strings, organs and choirs you remember are all there.
Credits
pd-101 wouldn't exist without the people who documented the CZ before us:
- Casio's phase distortion patent, US 4,658,691, and the CZ-101, CZ-1 and CZ-3000 operation manuals and the CZ MIDI specification.
- kasploosh.com for "CZ Spelunking" and its deep dive into CZ envelopes.
- Jeff McClintock's KVR forum post explaining how the CZ noise circuit really works.
- Edisyn by Sean Luke, and ajwills72/cz101, for their notes on the CZ sysex format.
- Oli Larkin's VirtualCZ manual and Electric Druid's write-up on phase distortion.
Features
- Phase distortion with the eight classic CZ waveforms: saw, square, pulse, double sine, saw-pulse and three resonant waves.
- Two lines with all four CZ line modes (1, 2, 1+1' and 1+2'), plus joined waveforms that alternate two waves cycle by cycle.
- Ring and noise modulation modelled on how the hardware actually does them.
- Three 8-step envelopes per line for pitch (DCO), timbre (DCW) and level (DCA), with CZ rate and level behaviour.
- Key follow and velocity for timbre, level and pitch, as on the CZ-1.
- CZ vibrato with four shapes, rate, depth and delay, calibrated against hardware.
- Octave and detune with the CZ's octave, note and fine fields.
- Portamento, adjustable pitch-bend range and sustain pedal.
- Optional DAC emulation that models the CZ's output filter for a closer match to the hardware's brightness. Turn it off for a clean signal.
- 100 factory presets decoded from original CZ sysex: Brass Ens., String Ens., Jazz Organ, Female Chorus, Koto, Shakuhachi and the rest.
Changelog
Releases
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Initial version