How Small Will They Get? The New Generation Super-Mini Audio Power Amplifiers

New generation super-miniature amplifiers are a result of the same miniaturization that has caused computers and cell phones to shrink. Products are shrinking at a rapid tempo. At the same time, manufacturers are packing in more and more features. You probably still recall the good old tube amps which would dominate the living room. While tube amps are even now well-liked amongst fanatics, audio amplifiers these days are 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. New developments in audio technology in regard to power efficiency of have allowed the development of a new generation of super-miniature audio amplifiers, such as Amphony's microFidelity Model 100. Even though these mini amps provide up to 50 Watts - plenty to drive a speaker to high volume, they are no larger than a deck of cards.

Past audio amplifiers with "Class-A" and "Class-AB" architectures have fairly low power efficiency. Only a small part of the consumed energy - typically in the order of 20% to 30% - is in fact transformed into audio by analog amplifiers. The remaining portion is radiated as heat. This requires that depending on the supported output power, analog audio amps have to afford extensive cooling which is achieved by using heat sinks. These heat sinks do not permit these amplifiers to be made very small.

The "Class-D" topology of digital amplifiers offers higher efficiency than analog amps. The efficiency normally ranges between 80% and 95%. This allows digital amps to be miniaturized. "Class-D" amplifiers employ a switching output stage. This stage introduces nonlinearities which creates audio distortion. This problem has had an influence on the triumph of digital amplifiers.

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 permits the amplifier to compensate for nonlinearities of the output switching stage and thus lower audio distortion to similar levels of analog amplifiers whilst preserving the audio efficiency of digital amplifiers.

These new generation miniature audio amplifiers open up applications where previous amplifiers would fail, such as speaker installations where space is premium, such as in-ceiling speakers and applications that connect speakers to a cable box or DVD/MP3 player.