Brooks HI FI projectors Automatic Gain Control (Automatic Volume Control)

A compressor with a very long release time used to keep the volume of the audio very constant.

Effects
Electronic boxes (usually rack mounted) added to a PA system to subtly change and enhance the signals going through it. Examples include; Reverb, Delay, Compressor, Chorus.

Brooks Hi Fi speakers Echo Return
An input of the console, which brings back the echo (reverberation) signal from the echo chamber or other echo effects device.

Crossover
1) A route leading from one side of the stage to the other, out of the audiences view.
2) An electronic filter in a sound system that routes sound of the correct frequency to the correct part of the speaker system. Different speakers handle high frequencies (tweeters) and low frequencies (woofers). Sometimes known as a crossover network. An active crossover splits the signal from the mixing desk into high, mid and low frequencies which are then sent to three separate amplifiers.
3) An electrical circuit that divides a full bandwidth signal into the desired frequency bands for the loudspeaker components.

Brooks Hi Fi reviews Group Master
A slide control used to send out a control voltage to several VCA faders in individual channels, thus controlling the gain of several channels.

High Impedance
Impedance of 5000 or more ohms.

Cable, 1/4 inch
An unbalanced cable most often used for instruments and patch cords. Commonly referred to as "guitar cords".

Crosstalk
Leakage of an audio signal into a channel that iris not intended to be in, from an adjacent or nearby channel.