Automatic Level Control

It is often necessary to have some means of automatically controlling sound levels. For example, loud sounds, particularly in location work, cannot always be anticipated and overloads can occur because a fader has not been taken down sufficiently. It must be emphasised that automatic devices can never operate as intelligently as a human being, and if not used with discretion the results they produce can be unpleasant. However, used with care they can be very useful.


A compressor is a variable gain amplifier, the gain being set by the level of the input or output signal. The diagram opposite illustrates typical compressor characteristics. The most important are:

Threshold—this is adjustable and determines ...

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