The term microphone preamplifier can either refer to the electronic circuitry within a microphone, or to a separate device or circuit that the microphone is connected to. In either instance, the purpose of the microphone preamplifier is the same. A microphone preamplifier is a sound engineering device that prepares a

microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...

signal to be processed by other equipment. Microphone signals are often too weak to be transmitted to units such as

mixing console A mixing console or mixing desk is an electronic device for Audio mixing (recorded music), mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals fro ...

s and recording devices with adequate quality. Preamplifiers increase a microphone signal to line level (i.e. the level of signal strength required by such devices) by providing stable

gain Gain or GAIN may refer to: Science and technology * Gain (electronics), an electronics and signal processing term * Antenna gain * Gain (laser), the amplification involved in laser emission * Gain (projection screens) * Information gain in de ...

while preventing induced noise that would otherwise distort the signal.Ballou, 1987, pp. 506–507. For additional discussion of signal level, see

Gain stage In audio engineering, a gain stage is a point during an audio signal flow that the engineer can make adjustments to the level,Thompson, Dan (2005). ''Understanding Audio''. Berklee Press. . such as a fader on a mixing console or in a DAW. Gain st ...

. A microphone preamplifier is colloquially called a microphone preamp, mic preamp, micamp, preamp (not to be confused with a control amplifier in high-fidelity reproduction equipment), mic pre and pre.

Technical details

The output voltage on a dynamic microphone may be very low, typically in the 1 to 100 microvolt range. A microphone preamplifier increases that level by up to 70 dB, to anywhere up to 10 volts. This stronger signal is used to drive equalization circuitry within an audio mixer, to drive external audio effects, and to sum with other signals to create an audio mix for audio recording or for live sound.

Functions

In addition to providing gain for the microphone signal, a microphone preamplifier as found in a sound mixer or as a discrete component typically also provides power to the microphone in the form of either 24 or 48 volt Phantom power.

In use

A microphone is a

transducer A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and con ...

and as such is the source of much of the coloration of an audio mix. Most

audio engineer An audio engineer (also known as a sound engineer or recording engineer) helps to produce a recording or a live performance, balancing and adjusting sound sources using equalization, dynamics processing and audio effects, mixing, reproduction ...

s would assert that a microphone preamplifier also affects the sound quality of an audio mix. A preamplifier might load the microphone with low impedance, forcing the microphone to work harder and so change its tone quality. A preamplifier might add coloration by adding a different characteristic than the audio mixer's built-in preamplifiers. Some microphones, for example condensers, must be used in conjunction with an impedance matching preamplifier to function properly. Some preamplifiers exist as one part of a channel strip, which can include other kinds of audio recording devices such as

compressor A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor. Compressors are similar to pumps: both increase the pressure on a fluid and both can tr ...

s, equalization (EQ),

noise gate A noise gate or gate is an electronic device or software that is used to control the volume of an audio signal. Comparable to a compressor, which attenuates signals ''above'' a threshold, such as loud attacks from the start of musical notes, no ...

s, and enhancers.

References

* {{Music technology Audio amplifiers Microphones