Demands regarding audio power and audio fidelity of recent speakers and home theater systems are always growing. At the heart of these systems is the audio amp. Recent audio amplifiers have to perform well enough to meet those always increasing demands. It is difficult to choose an amp given the huge range of types and concepts. I will explain some of the most widespread amplifier designs like "tube amps", "linear amplifiers", "class-AB" and "class-D" along with "class-T amps" to help you understand several of the terms normally used by amp makers. This essay should also help you figure out which topology is best for your particular application.
The fundamental operating principle of an audio amplifier is fairly basic. An audio amp will take a low-level music signal. This signal typically originates from a source with a comparatively high impedance. It subsequently converts this signal into a large-level signal. This large-level signal can also drive loudspeakers with small impedance. The sort of element used to amplify the signal is dependent on what amplifier architecture is used. Some amps even employ several kinds of elements. Usually the following parts are utilized: tubes, bipolar transistors in addition to FETs.
In addition, tube amps have quite low power efficiency and consequently radiate much power as heat. Tube amps, though, a fairly costly to manufacture and as a result tube amplifiers have mostly been replaced with amps employing transistor elements that are less expensive to produce.
Also, tube amps have quite low power efficiency and therefore dissipate much power as heat. Yet another drawback is the high price tag of tubes. This has put tube amplifiers out of the ballpark for many consumer products. Because of this, the bulk of audio products nowadays utilizes solid state amps. I am going to explain solid state amplifiers in the following paragraphs.
Class-AB amplifiers improve on the efficiency of class-A amplifiers. They make use of a series of transistors in order to break up the large-level signals into two separate regions, each of which can be amplified more efficiently. The larger efficiency of class-AB amplifiers also has two other benefits. First of all, the necessary number of heat sinking is minimized. Therefore class-AB amps can be manufactured lighter and smaller. For that reason, class-AB amps can be manufactured cheaper than class-A amplifiers. Class-AB amplifiers have a drawback however. Each time the amplified signal transitions from a region to the other, there will be certain distortion produced. In other words the transition between those 2 regions is non-linear in nature. Consequently class-AB amps lack audio fidelity compared with class-A amps.
In order to further improve the audio efficiency, "class-D" amps use a switching stage which is constantly switched between two states: on or off. None of these 2 states dissipates energy within the transistor. As a result, class-D amps regularly 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 which has to be removed from the amplified signal by employing a lowpass filter. Due to non-linearities of the pulse-width modulator and the switching transistor itself, class-D amps by nature have amongst the highest audio distortion of any audio amplifier.
To resolve the problem of large music distortion, modern switching amplifier styles incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amps (also known as "t-amplifier") use this type of feedback mechanism and for that reason can be made very small whilst attaining low audio distortion.
The fundamental operating principle of an audio amplifier is fairly basic. An audio amp will take a low-level music signal. This signal typically originates from a source with a comparatively high impedance. It subsequently converts this signal into a large-level signal. This large-level signal can also drive loudspeakers with small impedance. The sort of element used to amplify the signal is dependent on what amplifier architecture is used. Some amps even employ several kinds of elements. Usually the following parts are utilized: tubes, bipolar transistors in addition to FETs.
In addition, tube amps have quite low power efficiency and consequently radiate much power as heat. Tube amps, though, a fairly costly to manufacture and as a result tube amplifiers have mostly been replaced with amps employing transistor elements that are less expensive to produce.
Also, tube amps have quite low power efficiency and therefore dissipate much power as heat. Yet another drawback is the high price tag of tubes. This has put tube amplifiers out of the ballpark for many consumer products. Because of this, the bulk of audio products nowadays utilizes solid state amps. I am going to explain solid state amplifiers in the following paragraphs.
Class-AB amplifiers improve on the efficiency of class-A amplifiers. They make use of a series of transistors in order to break up the large-level signals into two separate regions, each of which can be amplified more efficiently. The larger efficiency of class-AB amplifiers also has two other benefits. First of all, the necessary number of heat sinking is minimized. Therefore class-AB amps can be manufactured lighter and smaller. For that reason, class-AB amps can be manufactured cheaper than class-A amplifiers. Class-AB amplifiers have a drawback however. Each time the amplified signal transitions from a region to the other, there will be certain distortion produced. In other words the transition between those 2 regions is non-linear in nature. Consequently class-AB amps lack audio fidelity compared with class-A amps.
In order to further improve the audio efficiency, "class-D" amps use a switching stage which is constantly switched between two states: on or off. None of these 2 states dissipates energy within the transistor. As a result, class-D amps regularly 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 which has to be removed from the amplified signal by employing a lowpass filter. Due to non-linearities of the pulse-width modulator and the switching transistor itself, class-D amps by nature have amongst the highest audio distortion of any audio amplifier.
To resolve the problem of large music distortion, modern switching amplifier styles incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amps (also known as "t-amplifier") use this type of feedback mechanism and for that reason can be made very small whilst attaining low audio distortion.
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