ABSTRACT
Microphones are transducers that typically have very low output signal levels. A voltage gain of 1000 (60 dB) or more may be required to bring the signals up to standard line levels, hence the name preamplifier. Amplifiers for such low-level signals are prone to problems unique to high-gain, low-noise electronic circuits. Microphone preamplifiers are available as stand-alone devices or as part of simple mixers or complex recording consoles. In this section, we will limit our discussion to preamplifiers and mixers intended for use with professional microphones that have balanced, low-impedance outputs.
