Wavefolder

What it is and how it works

A wavefolder doesn't cut the peaks that exceed a threshold: it flips them back. When the wave exceeds the limit, instead of staying flat it turns back downward; with more gain it folds several times. Each fold adds new slope reversals, hence many harmonics, with a bright, metallic, "vocal" timbre that is above all dynamic: the louder the input signal, the more harmonics come out. It is the basis of "West Coast" synthesis (Buchla with the 259's Timbre, Serge with the Wave Multipliers), as opposed to "East Coast" subtractive synthesis (Moog), which starts from rich waves and filters them.

With a sine wave, light folding produces a sound similar to a triangle/soft square wave; as the fold increases, high harmonics appear that move non-monotonically (some rise, others fall), with an effect similar to a filter that "talks".

Parameters one by one

• Fold / Drive / Gain: how far you exceed the threshold (number of folds). It is the main expressive control: modulating it with an envelope or LFO gives movement.
• Symmetry / Bias / Offset: shifts the wave up or down before the folding: asymmetric folds, even harmonics, more "nasal" timbre. It can generate DC: HP at 10–20 Hz after.
• Stages / Folds: number of stages in series (Serge, Buchla: 3–6).
• Shape: linear folding (triangular, harder) or sinusoidal (sine fold, softer).
• Mix: parallel with the clean signal.
• Pre-filter / Post-filter: an LP after the folder controls the highs (Buchla "low pass gate" approach: filter and VCA together, percussive and organic sound).
• Oversampling: indispensable; folding generates very high harmonics that cause aliasing.

Tools

• FL Studio stock: Distructor (Distortion module, Distructor model → Wave folder); Fruity WaveShaper (you can draw a curve that rises and then falls beyond the threshold: a static folder); in the stock synths, the internal waveshapers and distortions (Sytrus, Harmor) allow similar effects.
• Synths: Serum and Vital (distortion modes Lin. Fold / Sine Fold), Buchla Easel V in the V Collection (complex oscillator with Timbre), Make Noise and Eurorack modules (hardware), u-he Bazille.
• Effects: waveshapers with drawable curves (Fruity WaveShaper, Kilohearts Distortion and the like); check your saturator's manual to see whether it offers a fold or rectify mode.

When to use it and on what

• Mainly sound design, more than mixing:
• Basses: sine or triangle with envelope-modulated fold = a bass that "talks" (dubstep, neuro, techno). Keep the sub separate and clean (sine layer without folding below 100 Hz).
• Leads and plucks: fold + low pass gate = organic percussive sounds (Buchla style, ambient, IDM).
• Synthetic percussion: short sines with fold for metallic sounds and bells.
• Pads: light fold slowly modulated by an LFO for evolving textures.
• Effect on external sources (vocals, drums): unpredictable and noisy results; use it in parallel and with filters.

Starting settings

By genre

• Dubstep, neuro, riddim: complex basses with fold and multiband.
• Techno, IDM, experimental ambient: West Coast and synthetic percussion.
• Hyperpop: aggressive leads and basses.
• Pop: rare, only as color in sound design.

Wavefolder, clipper and saturation compared

For this reason the wavefolder is used as a "reverse" filter: instead of removing harmonics with a filter, you create them by modulating the fold. In the mix, treat it like a synth rich in highs: HP on the folded layer, de-esser or dynamic EQ if it pinches at 3–6 kHz, and space (reverb or delay) darker than usual.

Order in the patch

• Before the filter: the filter tames the folding (West Coast approach with low pass gate).
• After the filter: a folded resonant filter becomes very aggressive (dubstep sound design).
• After a compressor: more consistent timbre between loud and soft notes.

Common mistakes

• Fold on the sub: intermodulation and loss of the fundamental.
• Uncontrolled input level: the timbre changes with velocity or channel volume (sometimes intended, often not); put a compressor or limiter before if you want a stable timbre.
• Aliasing without oversampling.
• DC offset with shifted symmetry.

How to hear it

• On a 110 Hz sine wave, slowly raise the fold and watch the Fruity Parametric EQ 2 analyzer: the harmonics appear, alternate and "sing".
• Compare folding and hard clip at the same gain: the clip saturates and "stops", the folding keeps changing timbre.