Microphone signals are often too weak to be transmitted to units such as mixing consoles and recording devices with adequate quality.
[1] For additional discussion of signal level, see Gain stage.
The output voltage on a dynamic microphone may be very low, typically in the 1 to 100 microvolt range.
Some microphones, for example condensers, must be used in conjunction with an impedance matching preamplifier to function correctly.
Some preamplifiers exist as one part of a channel strip, which can include other kinds of audio recording devices such as compressors, equalization (EQ), noise gates, and enhancers.