Audio amplifier

An audio amplifier is an active device designed to amplify signals in the audio frequency range. Some audio amplifiers, such as microphone preamps or portable radio. may work with very small signal input. They need not always generate much output power and may be designed with integrated circuits or discrete components on printed boards.

Other audio amplifiers, such as for hi-fi or PA-systems, must develop large amounts of power output, sometimes thousands of watts.

In communication systems, two way radio etc, the frequency response of the audio circuits is restricted to a relatively narrow range, even less as of a telephone line which is less than 300 - 4kHz.

In hi-fi systems, a flat response is desired from 20Hz to even above the range of human hearing. In reality, the nature of even hi-fi speakers limit the performance, usually to a rounded off base below 40Hz but with a quite good response in the higher frequency responce, although being more or less flat depending of the design and quality.

Most audio amplifiers use transistors and/or integrated circuits like operational amplifiers or other specialized integrated circuits. Vacuum tubes were used before transistors became common in the late 60s but tube audio amplifiers are favored by audio enthusiasts and guitar players.

Audio amplifier types

The most popular type of power audio amplifiers are for hifi stereo systems, of which some of these are still being made with vacuum tubes, are shown below, with links within this site.

Car amplifier
Integrated amplifier
Mono amplifier
PA amplifier
Power amplifier
stereo amplifier
Subwoofer amplifier

Instrument amplifiers

The other type of power audio amplifiers are for instruments. These types are also with links within this site.

Acoustic amplifier
Bass amplifier
Guitar amplifier
keyboard amplifier