In an

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power su ...

, a presence control boosts the upper mid-range frequencies to make the sounds of voices and instruments with similar tonal ranges seem more "present". On television production studio's sound desk, there can be several presence controls, for several different, switchable, frequencies. There is a limit to the flexibility of such controls, and they are sometimes insufficient. If the degree of mis-match between microphones is great, simply increasing presence is not enough, and instead a sound engineer will use a

graphic equalizer Equalization, or simply EQ, in sound recording and reproduction is the process of adjusting the volume of different frequency bands within an audio signal. The circuit or equipment used to achieve this is called an equalizer. Most hi-fi eq ...

, sometimes several, each connected to an individual sound channel. Presence controls can also be found on

electric guitar An electric guitar is a guitar that requires external electric Guitar amplifier, sound amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar. It uses one or more pickup (music technology), pickups ...

amplifiers. The first presence control on a Fender amplifier, for example, appeared in 1954 on the

Twin Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of Twin Last Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two ...

. In 1955 it appeared on the 1/15 Pro-Amp, the 3/10

Bandmaster A bandmaster is the leader and conductor of a band, usually a concert band, military band, brass band or a marching band. British Armed Forces In the British Army, bandmasters of the Royal Corps of Army Music now hold the rank of staff ...

, the 2/10

Super Super may refer to: Computing * SUPER (computer program), or Simplified Universal Player Encoder & Renderer, a video converter/player * Super (computer science), a keyword in object-oriented programming languages * Super key (keyboard butto ...

, and the 4/10 Bassman. The original Fender presence control acted upon the amplifier's negative-feedback loop. As the level of "presence" was increased, so more and more of the higher frequencies in the negative-feedback loop were dumped to ground, leaving the low and mid-range frequencies. Increasing the presence resulted in there being less and less

negative feedback Negative feedback (or balancing feedback) occurs when some function (Mathematics), function of the output of a system, process, or mechanism is feedback, fed back in a manner that tends to reduce the fluctuations in the output, whether caused ...

on high frequencies. The effect varied according to

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of am ...

. Later Fender amplifiers used a different presence control. The presence control on the 1975 Fender Super Twin did not modify the negative feedback loop, but was an

active Active may refer to: Music * ''Active'' (album), a 1992 album by Casiopea * "Active" (song), a 2024 song by Asake and Travis Scott from Asake's album ''Lungu Boy'' * Active Records, a record label Ships * ''Active'' (ship), several com ...

equalization circuit, controlling the 3.9 kHz frequency range. It had the ability to both amplify (boost) and attenuate (cut), unlike the earlier presence control. In a 3-way loudspeaker system, with

tweeter A tweeter or treble speaker is a special type of loudspeaker (usually dome, inverse dome or horn-type) that is designed to produce high audio frequencies, typically from 2,000 to 20,000 Hertz, Hz. The name is derived from the high pitched sound ...

woofer A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 up to 200 Hz. The name is from the onomatopoeic English word for a dog's deep bark, " woof" (in contrast to a ' ...

, and

mid-range speaker A mid-range speaker is a loudspeaker driver that reproduces sound in the frequency range from 200 to 2,000 Hz. Mid-range drivers are usually cone types or, less commonly, dome types, or compression horn drivers. The radiating diaphragm o ...

, a presence control is simply a volume control for the mid-range speaker.{{cite encyclopedia, article=presence control, encyclopedia=Modern Dictionary of Electronics, author=Rudolf F. Graf, pages=586, publisher=Newnes, year=1999, isbn=0-7506-9866-7

References

Tone, EQ and filter Pitch (music)