A Brief Overview Of Music Amps

Stereo amps are at the very center of every home theater product. As the quality and output power demands of today’s loudspeakers increase, so do the demands of power amplifiers. It is challenging to select an amplifier given the large range of products and designs. I am going to describe some of the most common amp designs like “tube amps”, “linear amplifiers”, “class-AB” and “class-D” in addition to “class-T amplifiers” to help you comprehend some of the terms commonly utilized by amplifier suppliers. This guide should also help you figure out which topology is ideal for your specific application. The fundamental operating principle of an audio amplifier is fairly basic. An audio amplifier is going to take a low-level audio signal. This signal regularly originates from a source with a rather large impedance. It subsequently translates this signal into a large-level signal. This large-level signal may also drive loudspeakers with low impedance. As a way to do that, an amp employs one or more elements that are controlled by the low-power signal in order to create a large-power signal. Those elements range from tubes, bipolar transistors to FET transistors. A couple of decades ago, the most popular type of audio amplifier were tube amps. Tube amps make use of a tube as the amplifying element. The current flow through the tube is controlled by a low-level control signal. Thereby the low-level audio is converted into a high-level signal. One dilemma with tubes is that they are not extremely linear while amplifying signals. Aside from the original music, there are going to be overtones or higher harmonics present in the amplified signal. For that reason tube amplifiers have quite high distortion. However, this characteristic of tube amps still makes these popular. A lot of people describe tube amplifiers as having a warm sound versus the cold sound of solid state amps.

Another disadvantage of tube amplifiers, though, is the small power efficiency. The bulk of power that tube amplifiers use up is being dissipated as heat and merely a portion is being transformed into audio power. Moreover, tubes are pretty costly to build. Thus tube amplifiers have by and large been replaced by solid-state amplifiers which I am going to look at next.

The first generation types of solid state amps are referred to as “Class-A” amps. Solid-state amps use a semiconductor rather than a tube to amplify the signal. Regularly bipolar transistors or FETs are being utilized. In class-A amps a transistor controls the current flow according to a small-level signal. A number of amps make use of a feedback mechanism to reduce the harmonic distortion. If you need an ultra-low distortion amp then you might wish to investigate class-A amplifiers since they offer amongst the smallest distortion of any audio amps. Class-A amps, though, waste most of the energy as heat. For that reason they generally have big heat sinks and are quite bulky. Class-AB amps improve on the efficiency of class-A amplifiers. They utilize a number of transistors in order to split up the large-level signals into 2 separate regions, each of which can be amplified more efficiently. Because of the larger efficiency, class-AB amps do not require the same number of heat sinks as class-A amps. As a result they can be manufactured lighter and less expensive. However, this topology adds some non-linearity or distortion in the region where the signal switches between those regions. As such class-AB amps generally have larger distortion than class-A amplifiers. To further improve the audio efficiency, “class-D” amplifiers employ a switching stage which is continually switched between 2 states: on or off. None of these two states dissipates energy within the transistor. As a result, class-D amps frequently are able to achieve power efficiencies higher than 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered to remove the switching signal and recover the audio signal. 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 amps.

Modern amplifiers incorporate internal audio feedback to minimize the level of music distortion. One kind of small amplifiers which employs this kind of feedback is known as “class-T” or “t amp”. Class-T amps feed back the high-level switching signal to the audio signal processor for comparison. These amps exhibit small music distortion and can be made extremely small.