There are many audio effects created by multiplying and/or adding a scalar (single number) to each sample of a signal. Examples include: linear gain change, DC offset, polarity inversion, amplitude normalization, digital summing, amplitude fades, amplitude modulation, and stereo panning.
Effects based on this type of processing are categorized as linear effects. The other category of effects is called non-linear effects. Non-linear processing is based on any method other than scalar multiplication and addition.
Distortion audio effects process signals using a non-linear function. There are many audio effects that belong to the distortion category including: overdrive, fuzz, bit crushers, and aural exciters. Additionally, many audio technologies process signals in a non-linear manner such as guitar tube amplifiers, saturated analog tape, and transformers in an audio console. Distortion effects can also be created digitally.
This section will explore various types of distortion effects, starting with full-wave rectification.