Microphone preamplifier
A microphone preamplifier is an electronic circuit which amplifies the weak signal voltage at the output of a microphone after the microphone impedance converter to usable values. Most of the time this preamplifier is located in the input of an analog or digital mixer or it is an external electronic device. Its technical name is often English Mic Preamplifier or Mic Pre Amp .
Disambiguation
This is differentiated from a so-called microphone amplifier , which in a condenser microphone follows the microphone diaphragm electrically and sits in the microphone body . This microphone amplifier is not a voltage amplifier in the usual sense. Its sole task is to adapt the signals from the high-impedance capacitor capsule for the very low-impedance, symmetrical transmission through the microphone cable. This is an impedance conversion (or current amplification) from the very high-resistance capacitor capsule larger than 1 Giga-Ohm to the low-resistance output value below 200 Ohm in studio technology.
The terms microphone amplifier as an impedance converter after the membrane in the microphone body and the word microphone preamplifier as a necessary voltage amplifier are often confused or not clearly distinguished, especially in hobby technology.
General
The state of the art since around 1960 has been transistor preamplifiers . Before that and during a transition period there were tube preamps . Amplifiers with transistors have an almost linear frequency response and are low in noise. Tubes have a greater inherent noise , have greater distortion and a significantly higher power consumption.
Sometimes transistor amplifiers are said to have cold sound properties, while tubes should have a warm sound ; however, there is often no factual evidence for this. They are still used today for subjective reasons. Technically, ideal preamplifiers shouldn't have a sound of their own, because sound results from measurable linear and non-linear distortion. With tube preamps, an imprint in the sound as a so-called sound philosophy (a kind of esotericism) is tolerated.
literature
- Fritz Kühne: Low-frequency amplifier with tubes and transistors. 13th edition, Franzis Verlag, Munich, 1970
- Gustav Büscher, A. Wiegemann: Little ABC of electroacoustics. 6th edition, Franzis Verlag, Munich, 1972, ISBN 3-7723-0296-3
- Thomas Görne: Sound engineering. 1st edition, Carl Hanser Verlag, Leipzig, 2006, ISBN 3-446-40198-9
