Amplifiers provide the necessary power, measured in watts to drive the speakers.

If you are planning to go big with your car stereo you are going to need the power to match.

Rod Meagher Car Audio have an extensive range of amplifiers to accommodate from the most basic of car stereos, right through to window shattering spl applications.

Whether it be a mono for your subwoofer, a 2 channel for your speakers or even a 5.1 channel for a complete mobile media installation, we've got the gear to get you going. 

The "signal" is usually voltage or current. (so, an amplifier will generally increase the signal level).

In popular use, the term today usually refers to an electronic amplifier, often as in audio applications.

The relationship of the input to the output of an amplifier — usually expressed as a function of the input frequency — is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain.

A related device that emphasizes conversion of signals of one type to another (for example, a light signal in photons to a DC signal in amperes) is a transducer, or a sensor. However, a transducer does not amplify power.