Recent 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 getting smaller and smaller. In the past, tube amps would be commonplace and take up a big part of the living room. Tube amps still have their fair share of fanatics. Nonetheless they have been replaced by solid-state amps for the most part.
Modern solid-state amplifiers merge 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 regarding amplifier power efficiency, a new generation of super-miniature amps has become possible, such as the Amphony Model 100 microFidelity amp. Even though these amps are as small as a deck of cards, they are able to deliver up to 50 Watts power and without difficulty drive a speaker to full volume.
Past audio amplifiers with "Class-A" and "Class-AB" architectures have fairly low power efficiency. Only a small percentage 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 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 major drawback of "Class-D" amplifiers is the fact that digital "Class-D" amplifiers use a switching stage at the output which causes non-linearity and as a result some amount of distortion of the audio signal. This drawback has slowed the progress of digital amplifiers.
Some new amplifier technologies have emerged. Among those are "Class-T" and newer generation "Class-D" architectures. These types of new architectures, such as the technology used in Amphony's Model 100 use a feedback mechanism. The output signal is fed back to the amplifier input. This feedback permits the amplifier to compensate for nonlinearities of the output switching stage and consequently lower audio distortion to comparable levels of analog amplifiers while preserving the audio efficiency of digital amplifiers.
These latest miniature audio amplifiers open up applications where traditional amplifiers have failed. They are suited in particular for installations with minimum space, such as in ceiling speakers. Other applications include connecting speakers to a DVD/MP3 player or cable box.