Stereo amplifiers are at the very heart of each home theater product. As the quality and output power demands of today’s loudspeakers increase, so do the requirements of mini stereo amps. There is a big amount of amplifier designs and types. All of these vary regarding performance. I will explain some of the most popular amp terms such as “class-A”, “class-D” and “t amps” to help you figure out which of these amps is best for your application. Furthermore, after understanding this guide you should be able to comprehend the amp specs which producers show.
Simply put, the purpose of an audio amplifier is to translate a low-power music signal into a high-power audio signal. The high-power signal is big enough to drive a loudspeaker sufficiently loud. To do that, an amplifier uses one or more elements that are controlled by the low-power signal to create a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
Tube amplifiers were frequently used a couple of decades ago and utilize a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Sadly, tube amplifiers have a reasonably high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. Though, this characteristic of tube amps still makes these popular. A lot of people describe tube amps as having a warm sound versus the cold sound of solid state amps. A different drawback of tube amplifiers, however, is the low power efficiency. The bulk of power that tube amplifiers consume is being dissipated as heat and only a fraction is being converted into audio power. Yet another drawback is the big price tag of tubes. This has put tube amps out of the ballpark for the majority of consumer devices. As a result, the majority of audio products these days utilizes solid state amps. I am going to describe solid state amplifiers in the subsequent sections.
Solid-state amps utilize a semiconductor element, like a bipolar transistor or FET rather than the tube and the earliest kind is generally known as “class-A” amps. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps employ a feedback mechanism in order to reduce the harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest amongst all types of music amplifiers. These amps also typically exhibit quite low noise. As such class-A amplifiers are ideal for very demanding applications in which low distortion and low noise are vital. However, similar to tube amplifiers, class-A amplifiers have quite low power efficiency and the majority of the power is wasted.
Class-AB amps improve on the efficiency of class-A amplifiers. They employ a number of transistors in order to split up the large-level signals into two separate areas, each of which can be amplified more efficiently. Because of the larger efficiency, class-AB amplifiers do not need the same number of heat sinks as class-A amps. Therefore they can be made lighter and cheaper. When the signal transitions between the two separate regions, however, a certain level of distortion is being produced, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amplifiers.
Class-D amplifiers are able to attain power efficiencies higher than 90% by making use of a switching transistor which is continuously being switched on and off and therefore the transistor itself does not dissipate any heat. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Standard switching frequencies are between 300 kHz and 1 MHz. This high-frequency switching signal needs to be removed from the amplified signal by a lowpass filter. Normally a straightforward first-order lowpass is being utilized. Both the pulse-width modulator and the transistor have non-linearities that result in class-D amps having larger audio distortion than other types of amplifiers.
In order to resolve the problem of large audio distortion, new switching amplifier styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. A well-known architecture that uses this kind of feedback is generally known as “class-T”. Class-T amps or “t amps” achieve audio distortion which compares with the audio distortion of class-A amps while at the same time having the power efficiency of class-D amps. Thus t amps can be manufactured extremely small and still attain high audio fidelity.
The Best Way To Stream Audio To Bluetooth Music Receivers 