Spectral Posterize

A spectral effect that quantizes the magnitude of every frequency bin to a small set of evenly-spaced levels — the audio equivalent of crushing an image down to a few colours. The result ranges from a subtle metallic shimmer to a stark, pixelated "1-bit" render of the spectrum.

How it works

Spectral Posterize runs your signal through an FFT and, frame by frame, finds the loudest bin, normalizes every bin against it, then rounds each bin's level to the nearest of N steps before scaling it back. Phase is untouched, so the harmonic structure stays put while its energy is snapped to a coarse ladder. The left and right channels are analyzed independently against their own adaptive peak, so a true stereo source posterizes differently on each side and the image stays wide. Because it works in blocks, the output starts silent and swells in over the first instant of playback.

Controls

• Levels — how many magnitude steps survive, swept exponentially from 64 (subtle, nearly clean) down to 2 (binary — bins are either on or off). Fewer levels means harsher, more obviously digital posterizing.
• Drive — 1x to 8x gain applied before quantization, pushing quiet bins up past the lowest non-zero step so they survive instead of dropping out. Use it to keep detail alive at low Levels.
• Mix — dry/wet blend; fully wet by default.

Inputs & outputs

• In L / In R — the stereo signal to process; the two channels are quantized independently.
• Levels / Drive / Mix CV — voltage control over each matching knob; patch an envelope or LFO to make the spectrum dissolve and re-form.
• Out L / Out R — the processed stereo pair.

Tips

• Low Levels plus heavy Drive is the classic harsh "1-bit spectrum" sound; back Drive off for a cleaner, glassier quantization.
• Modulate Levels CV with a slow LFO to breathe between near-clean and fully crushed without touching the knob.
• Pull Mix back to layer the posterized spectrum under the dry signal for a gritty parallel texture.