The Harmony Synth takes your input signal and runs it through a fuzz section then two fully analog phase-locked loop based harmony synthesizers. The fuzz and harmony signals are then run through a resonant lowpass filter and a switchable amplitude tracking section. Individual level controls are available for the Fuzz, Harmony 1, and Harmony 2 signals plus a clean Instrument signal to blend your input with the synthesized voices.
The harmony synthesis circuits are (mostly) monophonic and identical to each other except for the interval selections available. The Range control adjusts the center frequency of the synthesizers and changes both the tracking range and tonal quality of the voices. It allows for them to be set to allow proper tracking, upward octave glitching, lower octave glitching, and anything in between. Faux polyphony can even be achieved by setting one voice with low Range to track low notes and another with high Range to track high notes. It's analog and not perfect but there are lots of tricks possible with just little tweaks of the Range.
Intervals available are:
Harmony 1: one octave down (-12 semitones), a perfect fifth shifted down one octave (-5 semitones), a perfect fourth (+5 semitones), a perfect fifth (+7 semitones), a major sixth (+9 semitones), and an octave up (+12 semitones)
Harmony 2: two octaves down (-24 semitones), one octave down (-12 semitones), a perfect fifth (+7 semitones), a major third shifted up one octave (+16 semitones), two octaves up (+24 semitones), and a perfect fifth shifted two octaves up (+31 semitones)
The Amplitude Tracking control allows the synthesized signals to follow the dynamics of your input signal. For stringed instruments, this means you get attack and decay that mimic the behavior of your strings. For everything, this means that the synthesized voices will follow swells, tremolo, and anything else that modulates your input amplitude.
Internal trimpots allow for adjustment of Instrument volume, Fuzz gate threshold, and a master volume control for the synthesized voices and fuzz. These can be adjusted to accommodate a great deal of input sources from the weakest guitar pickups to high-output synthesizers.
Internal voltage doubling allows for use of a standard center-negative 9VDC power supply while running internal components at 18V differential power for maximum headroom. The pedal is built with full-size Alpha potentiometers, Switchcraft jacks, Cliff bypass switch (wired for true bypass, naturally), low-noise metal film resistors, and tantalum decoupling and ceramic tone-shaping capacitors.
The Harmony Synth is an entirely new circuit developed here in Portland, OR. Everything from circuit design to PCB etching to silkscreening is done in-house for complete control over the quality of every effect.