An amplifier is a device which increases the amplitude of an electrical signal. Amplitude represents the "strength" of a signal, so amplification effectively means increasing signal strength.
In audio and video work there are several common types of amplifier. Some example are described below.
- Power amplifier: Large amplifier used in sound reinforcement systems. Usually has few (if any) controls other than on/off and level.
- Line amplifier: Small amplifier used to boost a mic-level signal to line-level.
- Powered mixer: A unit that combines a sound mixer and amplifier.
- Distribution amp (DA or VDA): Amplifier designed to take a video signal and amplify it enough o be sent to multiple sources. Also used to adjust the video and chroma levels.
- Proc amp: Processing amplifier, used to selectively adjust different parts of a video signal,e g. balancing colours.