Audio Amplifier
WARNING: This page is about a different car, the 2003 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
The purpose of an amplifier is to increase the power of a voltage or current signal. The output signal of an amplifier may consist of the same frequencies as the input signal or it may consist of only a portion of the frequencies of the input signal, as in the case of a subwoofer or a mid-range amplifier.
When the radio is turned on, the radio sends a voltage signal to the audio amplifier via the radio on signal circuit. This enables the audio amplifier to amplify the low level audio signals from the radio. The audio amplifier then sends the speaker output to the appropriate speaker.