A preamplifier, also referred to as a preamp, is a device typically used along with sound equipment to help improve the overall quality of sound. In order to accomplish this, the preamplifier helps prepare the main amplifier, which increases the power and sound of the equipment, for receiving the electronic signal. Through the help of the preamplifier and the main amplifier, the sound is not altered in quality, but it is much louder.

A preamplifier and main amplifier may be used for a home audio system of for live band performances. They may also be used in a music recording studio or built into a music mixing desk. A preamplifier may also be used with a television in order to improve antenna or satellite communication.

In order to prepare the main amplifier for the electronic signal it receives, the preamplifier emits a low level signal to line level. The preamplifier is often part of a turntable, pickup, transducer, or turntable. In the case of a home sound system, the preamplifier may simply switch to various line level sources in order to control the volume without truly amplifying the sound.

In the typical audio system, a preamplifier only supplies a voltage gain, which is generally somewhere between ten millivolts to one volt. The preamplifier does not, however, provide current. Rather, the second amplifier, which is referred to as the power amplifier, supplies the necessary current to the speakers.

A preamplifier may be incorporated into a sound system in a variety of ways. It may be placed inside the housing of the power amplifier that it corresponds with, or it may have its own housing. The preamplifier may also be kept close to the source of its electrical signal while maintaining a distance from the power amplifier, such as when it is near a hi-fi entertainment system or when it is part of the home computer. If the preamplifier has its own housing and is to be used with the sound system of a band, it may be anchored to microphones, turntables, an electric bass, or an electric guitar.