To understand phase distortion synthesis, we must first go back to its basics. Casio company created phase distortion, or PD. This company engineers launched the original idea for the CZ series of synthesizers, which involved a Cosmo Synth System. Isao Tomita later perfected the Cosmo Synth System. He was a Japanese synthesis-composer and one of the electronic music pioneers. The first CZ series of synths was quite expensive, so Casio used digital synthesis without filters to make it more affordable.
More on the Basics
The phase distortion technique was first used to mimic the thin sound of analog filters. This technique involved eight different waveforms: a standard saw-tooth, a square waveform, a pulse waveform, a double-sine waveform, and a half-sine waveform, as well as three waveforms with fake filter resonance. The waveforms with fake filter resonance include triangle waveforms, trapezoidal waveforms, and saw-tooth waveforms. The CZ synth plays only one waveform at a time.
Phase Distortion Synthesis: The Works
PD synth operates by reading a sine wavetable stored in its memory. The most significant pieces of an initial linear frequency counter are under envelope control and then transformed into a second phase angle signal. This signal reads the sine wave and transforms it into diverse wave shapes depending on the wiring.
Phase distortion synthesis is common in frequency modulation synthesis within hardware synthesizers. Both forms of audio synthesis are alike, but they operate differently. With phase modulation synthesis, the oscillator modulator has its own period. In contrast, phase distortion synthesis modulates each cycle identically and applies an angular modulator of straight-line segments synched to the same period on time.
In addition…
Interactive phase distortion is an improved version of phase distortion that involves FM synthesis. It has multiple oscillators combined in several settings that modulate each other using either ring modulation or phase modulation.
If you want to learn more about other types of synthesis, please consult our entries on subtractive, granular, wavetable, additive, and physical modeling, linear arithmetic synthesis.
