a amplifer that will boost the signal before it gets to your mixer or recorder (hints PRE)
a small device that boosts the electronic signal to the amplifier and can increase the fullness of the tone
a specialized amplifier designed to bring bring a signal to the right level for the mixing board/amplifier to deal with it
Preamplifier. Converts an electrical signal from a CD player or other music source into a stronger signal to drive a power amplifier. Also controls the source selection, volume, and treble and bass response.
Used only in higher end amplifiers, or in situations that require the sound to have more done with it, like when receiving cell phone signals, or anything else that begins really quiet. The pre amp makes the sound loud enough for the power amp to pick it up without distorting it.
A circuit unit which takes a small signal and amplifies it sufficiently to be fed into the power amplifier for further amplification. A pre-amp includes all of the controls for regulating tone, volume, and channel balance.