Preamplifier

A pre amplifier, with other spellings pre amp, preamp or preamplifier, with or without hyphens, is an amplifying circuit or unit. It amplifies the level of a weak signal in order to be able to be further processed.
Preamplifiers, or just preamps, are also stand alone units for various purposes. The most popular and searched for are for consumers but there are also units for research, science, industry and medical use.
Among those for audio to the right, preamps with tubes are commonly used. However often when the term tube preamplifier is used, it usually refers to a home stereo preamplifier.

A phono preamplifier can handle both MM and MC phono cartridges. It is either needed, if an MC cartridge is to be used and the (pre)amplifier has no MC-input, or if there is no phono input at all, as with many modern stereo amplifiers. Instead of replacing the amplifier, a phono preamplifier may be a simpler and cheaper option.

A microphone preamplifier, is used in nearly all computer soundcards. They are an essential part of recording studios. Usually in the front end of mixing boards but if not, or if better quality is desired, a stand alone unit gets neccessary. The most expensive have tubes. There are units with one, two, four or eight channels.

The guitar preamp is an essential thing to many guitar players. The gain is higher to get a sound with distortion or overdrive. Many of these use tubes.

A stereo preamplifier is like a stereo integrated amplifier but without a final amplifier inside.