How Tiny Will They Get? – The New Generation Super-Mini Audio Amps

Latest models of audio super-mini amplifiers prove that audio technology has gone the same path as computer technology and cell phones. Products are shrinking at a rapid tempo. At the same time, vendors are packing in more and more features. 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 package no larger than a DVD player. New developments in audio technology in regard to power efficiency of have permitted the development of a new generation of super-miniature audio amplifiers, such as Amphony’s microFidelity Model 100. Even though these amps are as small as a deck of cards, they are capable to deliver up to 50 Watts power and easily drive a speaker to full volume.

“Class-A” and “Class-AB” amplifier topologies were the two most important amplifier architectures of previous audio amplifiers. These technologies have relatively low power efficiency. Analog audio amplifiers by nature only convert a small percentage of the power they consume – normally in the order of 20% to 30% – into audio whereas a large part is dissipated as heat. Analog amplifiers therefore need considerable cooling which is done by heat sinks that are often bulky and prevent the amplifier from being made very small.

“Class-D” amplifiers are based on a digital design which offers larger power efficiency than “Class-A” or “Class-AB” amplifiers – normally in the order of 80% to 95%. Consequently only a small portion is wasted as heat which was the key in being able to miniaturize audio amplifier designs. One major problem which has slowed the progress of “Class-D” amplifiers is audio distortion which is caused by nonlinearities of the switching output stage.

Newer amplifier technologies have emerged such as “Class-T” and newer “Class-D” architectures. These technologies, such as the one used in Amphony’s Model 100 provide for a feedback of the output signal to the amplifier input. This feedback enables the amplifier to compensate for nonlinearities of the output switching stage and thus lower audio distortion to similar levels of analog amplifiers while preserving the audio efficiency of digital amplifiers.

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