Optical compressor

A compressor whose gain reduction is controlled by a lamp and a light-dependent resistor, giving a slow, smooth and very natural response.

Because the resistor changes resistance gradually as the lamp brightens and dims, an optical compressor cannot react instantly, and that lag is exactly why it sounds musical: transients slip through before the compression arrives, and the release eases back rather than snapping. The result is a gentle smoothing that thickens sustain without squeezing the attack, which suits country, blues and clean funk playing. It is the design behind several of the most revered compressor pedals.

Example: A compressor that smooths a chord without eating the initial pick attack is likely to be an optical design.

Optical compressor

See also