How Small Can They Get? The Latest Super-Mini Audio Amps

Latest types of audio super-mini amplifiers prove that audio technology has gone the same path as computer technology and cell phones. While the features are growing, the size of today's consumer products is becoming smaller and smaller. The majority of audio amplifiers would be tube amps in the past. Although a large number of fanatics still is fond of tube amplifiers, they have been substituted by solid state amps for the most part.

Modern solid-state amplifiers combine the conventional pre amp and power amp stages into a neat single box no larger than a DVD player. Thanks to latest developments in audio technology in terms of amplifier power efficiency, a new generation of super-miniature amps has become feasible, such as the Amphony Model 100 microFidelity amp. These mini amps use no more space than a deck of cards but deliver up to 50 Watts, which is sufficient to drive a speaker to high volume.

Past audio amplifiers with "Class-A" and "Class-AB" architectures have quite low power efficiency. Analog audio amplifiers by nature only convert a small portion of the power they consume - typically in the order of 20% to 30% - into audio while a large percentage is dissipated as heat. This requires that depending on the supported output power, analog audio amps have to offer extensive cooling which is accomplished by utilizing heat sinks. These heat sinks do not permit these amplifiers to be made very small.

The "Class-D" topology of digital amplifiers provides higher efficiency than analog amps. The efficiency typically ranges between 80% and 95%. This permits digital amps to be miniaturized. One main drawback of "Class-D" amplifiers is the fact that digital "Class-D" amplifiers use a switching stage at the output which creates non-linearity and therefore some amount of distortion of the audio signal. This disadvantage has slowed the advance of digital amplifiers.

More recent "Class-T" and newer "Class-D" amplifier architectures, such as Amphony's Model 100, incorporate a feedback mechanism where the output of the amplifier is fed back to the input. By using this feedback, the amplifier can compensate for nonlinearities of the output stage. This permits the distortion to be reduced to levels similar to analog audio amplifiers. At the same time the amplifier offers the high power efficiency of digital amplifiers.

These new generation miniature audio amplifiers are suited for a variety of new applications where previous audio amplifiers have failed. These applications include installations, such as in-ceiling installations, with minimum space or connecting speakers to a cable box or DVD/MP3 player where minimal space is important.