New generation super-miniature amplifiers are a result of the same miniaturization that has caused computers and cell phones to shrink. 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 replace by solid state amps for the most part. Today’s amps integrate traditional pre-amps and power amps and assemble everything neatly in a single package no larger than a VCR. A new generation of super-miniature amplifiers, such as the Amphony Model 100 microFidelity amp, has become possible due to new developments in audio technology regarding power efficiency. Even though these amps are as small as a deck of cards, they are capable to deliver up to 50 Watts power and without difficulty drive a speaker to full volume.
In the past, audio amplifiers would possess comparatively low power efficiency due to the "Class-A" and "Class-AB" architecture of analog amplifiers. 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 while a large portion is dissipated as heat. This requires that depending on the supported output power, analog audio amps have to provide substantial cooling which is accomplished by utilizing heat sinks. These heat sinks do not permit these amplifiers to be made very small.
"Class-D" amplifiers are based on a digital design which can provide larger power efficiency than "Class-A" or "Class-AB" amplifiers - normally in the order of 80% to 95%. As a result only a small portion is wasted as heat which was the key in being able to miniaturize audio amplifier designs. "Class-D" amplifiers use a switching output stage. click here This stage introduces nonlinearities which creates audio distortion. This difficulty 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. 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 provides the high power 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.