Rectify Fuzz

A full-wave rectifier fuzz with the classic "octave-up" snarl. It folds the negative half of your signal up onto the positive half, doubling the apparent fundamental and adding the spitting, gated edge of a vintage octave fuzz. Runs as true stereo — both channels are shaped independently, so a stereo source keeps its image.

How it works

Rectification takes the absolute value of the signal, so the part that used to dip below zero now mirrors above it. That fold halves the waveform period, which your ear reads as an octave jump plus a thick crown of harmonics. Bias adds a DC offset before the fold: at center you get pure, symmetric full-wave rectification (cleanest octave-up); pushed to either edge the fold becomes partial and asymmetric, dialing in grittier, more broken textures. A leaky DC blocker quietly removes the offset afterward so nothing thumps downstream.

Controls

• Drive — input pre-gain from 1x to 5x. More drive means more signal slammed into the rectifier — louder, denser, more aggressive.
• Bias — the pre-rectify offset, -1 to +1. Center (0) is the pure octave-up sweet spot; sweep toward the edges to thin and fracture the tone into partial rectification.
• Mix — wet/dry blend, 0% to 100%. Back it off to fold in just a ghost of the octave over the clean signal.

Inputs & outputs

• In L / In R — the stereo audio to rectify; feed a mono signal to both for identical, centered output.
• Drive / Bias / Mix CV — voltage control over each knob; patch an LFO or envelope to sweep the bias for shifting, vocal-like fuzz timbres, or to swell the drive and wet/dry blend over a phrase.
• Out L / Out R — the processed stereo pair.

Tips

• Center the Bias and feed a clean sine or bass for the purest octave-up effect — the rectified fold is loudest and most musical there.
• Modulate Bias CV with an LFO or envelope to make the fuzz breathe between clean octave and broken splatter.
• Low Mix values turn it into a subtle harmonic exciter rather than an all-out fuzz.