Sound reinforcement system
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A sound reinforcement system is an electromechanical system for accurately amplifying, reproducing, and sometimes recording audio, so that persons not near the original source may experience the sound as if they were.
The configuration of such a system depends on its intended application. A sound system, or public address system or PA system, typically has microphones, an amplifier, loudspeakers, and controls to mix the signals coming from the various micorphones or other input sources (such as phonograph turntables or tape recorders).
In the most basic of sound reinforcement systems, sound from a source enters a microphone, which is connected to an amplifier, which is connected to a loudspeaker enclosure. In professional live applications, additional equipment is often used. For example, in applications where multiple microphones or input sources are required, a mixing console (which enable sound engineers or disc jockeys to adjust the volume for each microphone or source individually) may be placed in the signal path, after the microphones. In quality critical situations, equipment such as an equalizer may be placed in the signal path before the amplifier. Quality sound reinforcement often requires the use of electronic audio measuring devices, such as an FFT analyzer, to optimize the system's performance in any given space.
Larger systems can have dozens of speakers and draw hundreds of kilowatts of power in order to reinforce what is being done on the stage, and to propagate audio across the entire listening area. Ideally, a sound reinforcement system should be designed, installed, and operated by a competent audio engineer.
Signal path
Most of the time when talking about sound reinforcement, you are talking about large format systems. The signal path for these types of systems is as follows:
Signal enters the chain via a directly connected instrument or a transducer (microphone) which is plugged into the multicore cable (often called a "snake") where it is split to carry the signal to the Front of the House and to the monitor consoles. Once in a channel on the console this signal can be equalized, panned and amplified. One might also patch it into an external effect processor present in the channel. Then signal will be routed internally in the console to a summation buss from where it will be output to the amplifiers. The amplifier will amplify the signal on the order of magnitudes greater, after which it is sent to another transducer (most likely a loudspeaker) for listening.