Presence (amplification)
Encyclopedia
In an amplifier
, a presence control controls "presence". A presence control boosts the upper mid-range frequencies. Thus by increasing the presence with the presence control, the sounds of voices and such instruments 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, sometimes several, each connected to an individual sound channel.
Presence controls can also be found on electric guitar
amplifiers. The first presence control on a Fender amplifier, for example, appeared in 1954 on the Twin
. In 1955 it appeared on the Pro-Amp, the 3/10 Bandmaster
, and the 4/10 Super
. 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 on high frequencies. The effect varied according to amplitude
.
Later Fender amplifiers used a different presence control. The presence control on the 1975 Super Twin did not modify the negative feedback loop, but was a real equalization
control, controlling the 3.9kHz frequency range. It had the ability to both amplify and reduce ("boost" and "cut" in amplification terminology), unlike the earlier presence control. It was active equalization.
In a 3-way loudspeaker system, with tweeter
, woofer
, and mid-range speaker
, a presence control is simply a volume control for the mid-range speaker.
Amplifier
Generally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
, a presence control controls "presence". A presence control boosts the upper mid-range frequencies. Thus by increasing the presence with the presence control, the sounds of voices and such instruments 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, sometimes several, each connected to an individual sound channel.
Presence controls can also be found on electric guitar
Electric guitar
An electric guitar is a guitar that uses the principle of direct electromagnetic induction to convert vibrations of its metal strings into electric audio signals. The signal generated by an electric guitar is too weak to drive a loudspeaker, so it is amplified before sending it to a loudspeaker...
amplifiers. The first presence control on a Fender amplifier, for example, appeared in 1954 on the Twin
Fender Twin
The Fender Twin is a guitar amplifier made by Fender. It was introduced in 1952, two years before Fender began selling Stratocaster electric guitars. The amps are known for their characteristically clean tone....
. In 1955 it appeared on the Pro-Amp, the 3/10 Bandmaster
Fender Bandmaster
The Fender Bandmaster was a musical instrument amplifier made by Fender. It was introduced in 1953 and discontinued in 1974. This page focuses solely on the Bandmaster...
, and the 4/10 Super
Fender Super
The Fender Super was a guitar amplifier made by Fender. It was originally called the Dual Professional and was introduced in 1947. The Dual Professional included two 10" Jensen speakers. It was renamed the Super in fall of 1947.-See also:*Fender Super Reverb...
. 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 on high frequencies. The effect varied according to amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
.
Later Fender amplifiers used a different presence control. The presence control on the 1975 Super Twin did not modify the negative feedback loop, but was a real equalization
Equalization
Equalization, is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in sound recording and reproduction but there are many other applications in electronics and telecommunications. The circuit or equipment used...
control, controlling the 3.9kHz frequency range. It had the ability to both amplify and reduce ("boost" and "cut" in amplification terminology), unlike the earlier presence control. It was active equalization.
In a 3-way loudspeaker system, with tweeter
Tweeter
A tweeter is a loudspeaker designed to produce high audio frequencies, typically from around 2,000 Hz to 20,000 Hz . Some tweeters can manage response up to 65 kHz...
, woofer
Woofer
Woofer is the term commonly used for a loudspeaker driver designed to produce low frequency sounds, typically from around 40 hertz up to about a kilohertz or higher. The name is from the onomatopoeic English word for a dog's bark, "woof"...
, and mid-range speaker
Mid-range speaker
A loudspeaker driver that produces the frequency range from approximately 300–5000 hertz is known as a mid-range.Midrange drivers are usually cone types or, less commonly, dome types, or compression horn drivers...
, a presence control is simply a volume control for the mid-range speaker.