Pitch Shifter

A varispeed pitch shifter that raises or lowers the pitch of whatever you feed it. It is the lo-fi, characterful kind — think tape sped up or slowed down, not a transparent studio harmonizer — so it adds grit and motion as well as transposition.

How it works

Audio is written into a short circular buffer at a fixed rate, then read back out at a variable rate. Read faster than you write and the pitch rises; read slower and it falls. Because the read pointer chases the write pointer around a fixed loop, holding a shift produces the familiar varispeed glitches and zipper artifacts — part of the charm. The shift is a linear rate offset rather than true semitone tracking, so this is not a 1V/oct device.

Controls

  • Shift — how far the pitch moves: up speeds playback for a brighter, higher sound; down slows it for a darker, lower one, eventually freezing into a held drone at the bottom. Small moves around center do most of the work; the control saturates well before the dial's extremes.
  • Mix — blends the dry input against the shifted voice, from 0% fully dry up to 100% fully wet. Leave it wide open for straight transposition, or pull it back to tuck a slightly detuned copy under the original for chorus, doubling, and thickening.

Inputs & outputs

  • In L / In R — the audio you want to shift. Mono? Just use L — that one signal is processed once and sent to both outputs. Patch a stereo pair and each side gets its own buffer and read pointer through the shared knobs, so a wide source stays wide through the shift.
  • Shift / Mix CV — voltage control over the two knobs; patch an LFO into the pitch CV for vibrato and wobble or an envelope for tape-stop dives, and modulate Mix to swell the shifted voice in and out under the dry signal.
  • Out L / Out R — the pitch-shifted signal. With stereo in but only L cabled, the channels fold to mono automatically so nothing goes missing.

Tips

  • Send a slow envelope or ramp into PTCH for dramatic tape-stop and pitch-dive effects.
  • Push Shift to its lowest reach to freeze the read pointer into a drone or glitch texture, then modulate PTCH to coax it back to life.