Stereo amps are at the very core of every home theater product. As the quality and output power requirements of today’s loudspeakers increase, so do the requirements of music amps. There is a large amount of amplifier concepts and models. All of these vary in terms of performance. I am going to describe a few of the most common amp terms such as “class-A”, “class-D” and “t amps” to help you figure out which of these amps is ideal for your application. In addition, after reading this article you should be able to understand the amp specifications that producers issue. The basic operating principle of an audio amp is fairly clear-cut. An audio amp is going to take a low-level music signal. This signal usually originates from a source with a comparatively large impedance. It subsequently converts this signal into a large-level signal. This large-level signal may also drive loudspeakers with small impedance. Determined by the type of amp, one of several kinds of elements are used in order to amplify the signal such as tubes as well as transistors.
Tube amps used to be popular some decades ago. A tube is able to control the current flow in accordance to a control voltage which is attached to the tube. Sadly, tube amplifiers have a reasonably high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. On the other hand, this characteristic of tube amps still makes these popular. Many people describe tube amplifiers as having a warm sound versus the cold sound of solid state amplifiers.
Besides, tube amps have quite low power efficiency and therefore dissipate a lot of power as heat. Also, tubes are rather expensive to manufacture. Thus tube amplifiers have by and large been replaced by solid-state amps which I will glance at next. The first generation types of solid state amplifiers are referred to as “Class-A” amps. Solid-state amplifiers utilize a semiconductor instead of a tube to amplify the signal. Typically bipolar transistors or FETs are being used. In a class-A amp, the signal is being amplified by a transistor which is controlled by the low-level audio signal. Class-A amps have the lowest distortion and usually also the smallest amount of noise of any amplifier architecture. If you require ultra-low distortion then you should take a closer look at class-A models. The major downside is that just like tube amplifiers class A amplifiers have quite low efficiency. Because of this these amplifiers need large heat sinks in order to radiate the wasted energy and are typically quite heavy. Class-AB amps improve on the efficiency of class-A amplifiers. They use a number of transistors in order to split up the large-level signals into two separate regions, each of which can be amplified more efficiently. As such, class-AB amplifiers are typically smaller than class-A amps. When the signal transitions between the 2 separate areas, however, a certain level of distortion is being generated, thus class-AB amplifiers will not achieve the same audio fidelity as class-A amplifiers. In order to further improve the audio efficiency, “class-D” amplifiers use a switching stage which is constantly switched between 2 states: on or off. None of these 2 states dissipates power inside the transistor. Therefore, class-D amplifiers frequently are able to attain power efficiencies beyond 90%. The switching transistor, which is being controlled by a pulse-width modulator generates a high-frequency switching component that needs to be removed from the amplified signal by using a lowpass filter. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amplifiers exhibiting bigger audio distortion than other types of amps.
To solve the dilemma of large audio distortion, modern switching amp designs incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. One kind of mini audio amplifiers that employs this type of feedback is called “class-T” or “t amp”. Class-T amplifiers feed back the high-level switching signal to the audio signal processor for comparison. These amplifiers have small music distortion and can be made very small.
Exactly How Do Bluetooth Music Receivers Compare With Bluetooth Loudspeakers? 