ABSTRACT
A compressor works like an automatic volume control. It uses the envelope of a signal to control the signal’s level, keeping the output volume relatively constant even when the input volume changes.
For most of the history of film and TV sound, compressors-and their close cousins, limiters-were used sparingly. Distortion-free compressors were hard to build, so their use was restricted to technical necessities like avoiding high-frequency problems.1 But in the late 1960s, relatively clean units started to appear on the market, and soon they were considered essential tools-first in music production, then to increase loudness at radio and TV transmitters, and finally in postproduction.
