Brooks KS-55 Amplifier (Power amp, Head)

It's the part of the sound system that actually magnifies or "amplifies" the sound. In other words, it makes stuff louder.

Amplifier
Sound equipment that converts the low voltage, low current signal from a tape deck, mixer etc. into a higher current signal suitable for driving speakers. See Power Amplifier, Crossover.

Brooks Cinema XR 607 Central Processing Unit
1) The main "brain" chip of a computer that performs the calculations and execution of instructions.
2) The main housing of a computer that contains the "brain" chip as opposed to other pieces of the computer system such as keyboards, monitors, etc.

Level
Sets output volume of individual PA input channels. Usually positioned as sliders at the bottom of the soundboard.

Brooks Cinema KP 30 Compressor
A signal processing device that does not allow as much fluctuation in the level of the signal above a certain adjustable or fixed level.

Line Out (Output, Send)
Where a signal leaves the board or component.

Foot Switch
A switch placed on the floor and pressed by a musician to do various functions.

Delay
Outboard sound equipment that can momentarily stores a signal being sent to part of a P.A. system so that delayed reinforced sound reaches the audience at the same time as live sound from the stage.