If locally powered, this can also be termed an active loudspeaker, meaning it contains an audio amplifier that can drive power to the speaker drivers.

One acts as a combination mixer-oscillator, one as an audio amplifier, and two as intermediate-frequency amplifiers.

A crude but simple example of this concept can be observed in the volume control of an audio amplifier.

In fact, they were in most respects conventional audio amplifier designs with unusual power supply circuits.

Some units of this phone made a slight hissing noise when connected to an external audio amplifier.

At either end of the 10in-wide aluminium enclosure sit two tiny speakers that are driven by a lively built-in amplifier.

It has a built-in amplifier, so you can just plug in your headphones and go.

It features 88 progressively-weighted keys, plus a built-in amplifier driving the on-board stereo speakers.

The guitar's case had a small built-in amplifier and the guitar itself had a very short-scale 18-fret neck, which proved popular with beginners.

Active subwoofers include a built-in amplifier.