Saturation

How nonlinearity adds second and third harmonics, rounds peaks, and changes perceived loudness.

Related

Electric guitarEqualizerBus

The question

Saturation is often used as a synonym for distortion. It does come from nonlinearity, but the aim is usually not damage, it is extra harmonics and rounded peaks that make a sound sit forward at the same loudness.

How it works

The signal passes through a curved transfer function, and a sine wave gains integer multiples of its frequency. A symmetric curve produces mostly third harmonic and sounds hard; an asymmetric one adds second harmonic and reads warmer. More input means more harmonics and soft peak clipping, so dynamics tighten naturally. Digital versions need oversampling, or high harmonics fold back as aliasing.

Settings and what you hear

Drive sets the level into the curve, mix controls dry and wet, and output trim stops the effect from being just louder. A light push solidifies a vocal; a heavy push makes cymbals sandy. Bass gains midrange presence after saturation.

What to listen for

Hear a clean sine or bass first, then add saturation and notice the new harmonics and rounded peaks. Use a small amount on drums and hear whether the kit gets denser rather than broken.

Common misconceptions

That saturation is a distortion pedal; that more drive is better without output compensation; that saturation hides mud.

Sources

• Udo Zölzer, DAFX — Digital Audio Effects, nonlinear processing chapter — background checked, not quoted
• Sound On Sound, saturation explained — harmonic behaviour checked, not quoted

Used for fact-checking only; all prose is original.