Editing Sound reinforcement system (section)

==Basic concept==
[[Image:Basic PA.svg|thumb|right|300px|A basic sound reinforcement system that would be used in a small music venue. The main [[loudspeaker]]s for the audience are to the left and right of the stage. A row of [[Foldback (sound engineering)|monitor speakers]] pointing towards the onstage performers helps them hear their singing and playing. The audio engineer sits at the back of the room, operating the [[mixing console]], which shapes the sound and volume of all of the voices and instruments.]]

A typical sound reinforcement system consists of; input [[transducer]]s (e.g., [[microphone]]s), which convert [[sound energy]] such as a person [[singing]] into an electric signal, [[Audio signal processing|signal processors]] which alter the signal characteristics (e.g., [[Equalization (audio)|equalizers]] that adjust the bass and treble, [[Dynamic range compression|compressors]] that reduce signal peaks, etc.), [[amplifier]]s, which produce a powerful version of the resulting signal that can drive a [[loudspeaker]] and output transducers (e.g., loudspeakers in [[speaker cabinet]]s), which convert the signal back into sound energy (the sound heard by the audience and the performers). These primary parts involve varying numbers of individual components<ref name="sound-equipment-1">[https://trungchinhaudio.vn/am-thanh-hoi-truong.html Audio Systems - Loudspeakers, Amplifiers, Signal Processors, Mixers, Music Source & Microphones] {{webarchive|url=https://web.archive.org/web/20120108002100/http://www.soundsinc.co.uk/sound-equipment.php|date=2012-01-08}}. Retrieved on 2024-07-24.</ref> to achieve the desired goal of reinforcing and clarifying the sound to the audience, performers, or other individuals.

===Signal path===
Sound reinforcement in a large format system typically involves a signal path that starts with the signal inputs, which may be instrument [[Pick up (music technology)|pickups]] (on an [[electric guitar]] or [[electric bass]]) or a microphone that a vocalist is singing into or a microphone placed in front of an instrument or [[guitar amplifier]]. These signal inputs are plugged into the input jacks of a thick [[Audio multicore cable|multicore cable]] (often called a ''snake''). The snake then delivers the signals of all of the inputs to one or more [[mixing console]]s.

In a coffeehouse or small nightclub, the snake may be only routed to a single mixing console, which an audio engineer will use to adjust the sound and volume of the onstage vocals and instruments that the audience hears through the main speakers and adjust the volume of the [[Foldback (sound engineering)|monitor speakers]] that are aimed at the performers.

Mid- to large-size performing venues typically route the onstage signals to two [[mixing console]]s: the [[front of house]] (FOH), and the [[stage monitor system]], which is often a second mixer at the side of the stage. In these cases, at least two [[audio engineer]]s are required; one to do the main mix for the audience at FOH and another to do the monitor mix for the performers on stage.

Once the signal arrives at an input on a mixing console, this signal can be adjusted in many ways by the sound engineer. A signal can be [[Equalization (audio)|equalized]] (e.g., by adjusting the bass or treble of the sound), [[Dynamic range compression|compressed]] (to avoid unwanted signal peaks), or [[Panning (audio)|panned]] (that is sent to the left or right speakers). The signal may also be routed into an external [[effects processor]], such as a [[reverb]] effect, which outputs a ''wet'' (effected) version of the signal, which is typically mixed in varying amounts with the ''dry'' (effect-free) signal. Many electronic [[effects unit]]s are used in sound reinforcement systems, including [[digital delay]] and [[reverb]]. Some concerts use [[pitch correction]] effects (e.g., [[AutoTune]]), which electronically correct any out-of-tune singing.

Mixing consoles also have additional ''sends'', also referred to as ''auxes'' or ''aux sends'' (an abbreviation for "auxiliary send"), on each input channel so that a different mix can be created and sent elsewhere for another purpose. One usage for aux sends is to create a mix of the vocal and instrument signals for the monitor mix (this is what the onstage singers and musicians hear from their [[Foldback (sound engineering)|monitor speakers]] or [[in-ear monitor]]s). Another use of an aux send is to select varying amounts of certain channels (via the aux send knobs on each channel), and then route these signals to an effects processor. A common example of the second use of aux sends is to send all of the vocal signals from a [[rock band]] through a reverb effect. While reverb is usually added to vocals in the main mix, it is not usually added to electric bass and other [[rhythm section]] instruments.

The processed input signals are then mixed to the master faders on the console. The next step in the signal path generally depends on the size of the system in place. In smaller systems, the main outputs are often sent to an additional equalizer, or directly to a [[power amplifier]], with one or more loudspeakers (typically two, one on each side of the stage in smaller venues, or a large number in big venues) that are connected to that amplifier. In large-format systems, the signal is typically first routed through an equalizer then to a [[Audio crossover|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 signals. Low-frequency signals are sent to amplifiers and then to [[subwoofer]]s, and middle and high-frequency sounds are typically sent to amplifiers which power full-range [[Loudspeaker|speaker]] cabinets. Using a crossover to separate the sound into low, middle and high frequencies can lead to a "cleaner", clearer sound (see [[bi-amplification]]) than routing all of the frequencies through a single full-range speaker system. Nevertheless, many small venues still use a single full-range speaker system, as it is easier to set up and less expensive.