Sound reinforcement system
From Wikipedia, the free encyclopedia
A sound reinforcement system is an electromechanical system for accurately amplifying, reproducing, and sometimes recording audio, so that individuals distant from the original source may experience the sound as if they were close to the sound source.
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 microphones or other input sources (such as phonograph turntables or tape recorders).
In the most basic sound reinforcement system, sound from a source is picked up by a microphone, the sound signal is boosted using an amplifier, and then projected by a loudspeaker enclosure. In live sound applications, additional equipment is often used. For example, in applications where multiple microphones or input sources are required, a mixing console (which enables 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 and propagate audio across the entire listening area. Sound reinforcement systems need to be designed, installed, and operated by a trained audio engineer, who will be able reduce the risks inherent in the use of such a system, such as high sound pressure levels which may damage listeners' hearing.
[edit] Signal path
Sound reinforcement in a large format system typically uses the following signal path:
A 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.
The signal can be routed internally to either a summation bus, also known as a group, in order to allow the engineer to control the levels of several related signals at once. A good example of this is controlling several individually miked drums or backup singers. From here each signal is typically routed through the stereo masters on a console (left and right, or balance, pan, etc.). Additionally, each signal can be sent to separate outputs from the main console, typically referred to as Auxiliary sends, or "Auxes."
The next step in the signal path generally depends on the size of the system in place. In smaller systems, the main outputs would be sent to an additional equalizer, or directly to a power amplifier, with one or more loudspeakers (typically two) then connected to that amplifier. In large-format systems, the signal is first routed through an additional equalizer then to a crossover. A crossover splits the signal into multiple frequency bands, with each band being sent to separate amplifiers and speaker enclosures for low-, middle-, and high-frequency sounds.
Once the signal has reached the amplifiers it is typically no longer considered a "signal" per se, as the voltages and currents now present greatly exceed those experienced throughout the rest of the signal path.
[edit] See also
- Computer speaker
- Public Address system (PA system)
- Instrument amplifier
