Overdrive (music)

Distortion (music)

A well-used "Turbo Distortion" guitar effect pedal made by Boss

Distortion and overdrive are forms of audio signal processing used to alter the sound of amplified electric musical instruments, usually by increasing their gain. Distortion is most commonly used with the electric guitar, but may also be used with other electric instruments. Guitarists playing electric blues originally obtained an overdriven sound by turning up their vacuum tube-powered guitar amplifiers to high volumes. While overdriven tube amps are still used to obtain overdrive in the 2010s, especially in genres like blues and rockabilly, a number of other ways to produce distortion have been developed since the 1960s, such as distortion effect pedals.

The effects alter the instrument sound by clipping the signal, adding sustain and harmonic and inharmonic overtones and leading to a compressed sound that is often described as "warm" and "dirty", depending on the type and intensity of distortion used. The terms distortion and overdrive are often used interchangeably; where a distinction is made, "distortion" is used to denote a more extreme version of the effect than "overdrive". "Fuzz" is a term used to describe a particular form of distortion originally created by guitarists using faulty equipment (such as a misaligned valve tube, see below), which has been emulated since the 1960s by a number of "fuzzbox" effects pedals.

Distortion, overdrive, and fuzz can be produced by effects pedals, rackmounts, pre-amplifiers, power amplifiers, speakers and (since the 2000s) by digital amplifier modeling devices and audio software. These effects are used with electric guitars, electric basses (fuzz bass), electronic keyboards, and more rarely as a special effect with vocals. While distortion is often created intentionally as a musical effect, musicians and sound engineers sometimes take steps to avoid distortion, particularly when using PA systems to amplify vocals or when playing back prerecorded music.