5 Power amplifiers

5.6 Distortion

Distortion comes mainly in two forms, when it comes to power amplifiers. First there's amplitude distortion, which mostly occurs due to clipping (solid state 5.10 Solid state) or saturation (tube 5.11 Tube): this is distortion of the instantaneous signal level (=amplitude). Secondly, there's crossover distortion which occurs at the zero crossing point of the signal, which usually relates to a bias problem in class AB 5.9 Topologies amps. Crossover distortion has no connection to frequency crossovers 6.6 Crossovers.

Amplitude distortion increases with increasing signal levels, while crossover distortion decreases with increasing signal levels.

When it comes to bass guitar, distortion is a mixed bag. Amplitude distortion from a power amplifier is usually unwanted, but tube saturation is sought after by many bass guitar players. It puts a bit of "growl" into the sound. Crossover distortion is never favoured.

© Joris van den Heuvel 2001-2009