Brooks GT 845 Gain

1) Knob usually found at the top of each input channel on the soundboard. Used to set input levels of the separate channels to relatively equal positions.
2) The amount of increase in audio signal strength, often expressed in dB.

Line Input
An input designed to take a line level signal.

Brooks Cinema xm 808 Grouping
1) Controlling the gain of several individual channels with a Group Fader.
2) The mixing together of several individual audio signals to send a mixed signal out of the console to record a track on a multitrack tape machine.

Fly In
1) To add sounds into a mix or recording that have no synchronization.
2) An application of this where a performance from one part of a tune is recorded and then recorded back into the recording at a different time in the recording.

Brooks KS-55 Leakage
Sounds from other instruments and sources that were not intended to be picked up by the microphone.

Insert
1) A punch in of the all of the tracks being recorded in a recording session.
2) On Solid State Logic consoles, placing an outboard piece of gear in the channel by patching and activating a switch.

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.

Frequency
Practically speaking, high frequency means high pitch and low frequency means low pitch.