an electronic amplifier used to improve the signal-to-noise ratio of an electronic device. It boosts a low-level signal to an intermediate level before it is transmitted to the main amplifier
Sometimes shortened to: preamp
preamplifier in American English
(priˈæmpləˌfaɪər)
noun
in a radio, phonograph, etc., an auxiliary amplifier for boosting the voltage of a weak signal before it reaches the input of the main amplifier