Audio Amplifier

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 amplifier control circuit. The gain control signal circuit allows the radio to recognize that an amplifier is present. Once the radio detects the amplifier, the radio will output low level audio signals to the amplifier. With the amplifier enabled, the signal that drives the speaker is now amplified.