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None of latest stereo products would be feasible without the aid of recent music amps which try to satisfy higher and higher requirements concerning power and music fidelity. There is a large quantity of amp designs and models. All of these differ when it comes to performance. I am going to describe a few of the most popular amplifier terms including "class-A", "class-D" and "t amps" to help you figure out which of these amps is ideal for your application. In addition, after understanding this essay you should be able to comprehend the amplifier specs that makers show.
The fundamental operating principle of an audio amplifier is fairly clear-cut. An audio amplifier is going to take a low-level music signal. This signal regularly originates from a source with a rather large impedance. It subsequently converts this signal into a large-level signal. This large-level signal can also drive speakers with low impedance. To do that, an amp uses one or several elements which are controlled by the low-power signal in order to generate a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
A few decades ago, the most popular type of audio amplifier were tube amplifiers. Tube amplifiers employ a tube as the amplifying element. The current flow through the tube is controlled by a low-level control signal. In that way the low-level audio is transformed into a high-level signal. Tubes, on the other hand, are nonlinear in their behavior and are going to introduce a fairly large level of higher harmonics or distortion. These days, tube amps still have a lot of followers. The primary reason is that the distortion which tubes bring about are frequently perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold".
The first generation models of solid state amps are generally known as "Class-A" amps. Solid-state amps utilize a semiconductor instead of a tube to amplify the signal. Usually 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. In terms of harmonic distortion, class-A amps rank highest among all types of audio amplifiers. These amps also typically exhibit quite low noise. As such class-A amps are perfect for quite demanding applications in which low distortion and low noise are essential. However, similar to tube amplifiers, class-A amps have quite low power efficiency and most of the power is wasted.
Class-AB amps improve on the efficiency of class-A amps. They utilize a number of transistors in order to split up the large-level signals into two distinct areas, each of which can be amplified more efficiently. Because of the larger efficiency, class-AB amplifiers do not require the same amount of heat sinks as class-A amplifiers. Consequently they can be manufactured lighter and less expensive. Nonetheless, this topology adds some non-linearity or distortion in the region where the signal switches between those areas. As such class-AB amps usually have higher distortion than class-A amps.
Class-D amps improve on the efficiency of class-AB amplifiers even further by making use of a switching transistor that is constantly being switched on or off. Thereby this switching stage barely dissipates any power and consequently the power efficiency of class-D amps usually surpasses 90%. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component that has 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 kinds of amplifiers.
Newer amplifiers incorporate internal audio feedback in order to minimize the amount of music distortion. One type of audio amplifiers which makes use of this kind of feedback is known as "class-T" or "t amplifier". 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 extremely small.
The fundamental operating principle of an audio amplifier is fairly clear-cut. An audio amplifier is going to take a low-level music signal. This signal regularly originates from a source with a rather large impedance. It subsequently converts this signal into a large-level signal. This large-level signal can also drive speakers with low impedance. To do that, an amp uses one or several elements which are controlled by the low-power signal in order to generate a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
A few decades ago, the most popular type of audio amplifier were tube amplifiers. Tube amplifiers employ a tube as the amplifying element. The current flow through the tube is controlled by a low-level control signal. In that way the low-level audio is transformed into a high-level signal. Tubes, on the other hand, are nonlinear in their behavior and are going to introduce a fairly large level of higher harmonics or distortion. These days, tube amps still have a lot of followers. The primary reason is that the distortion which tubes bring about are frequently perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold".
The first generation models of solid state amps are generally known as "Class-A" amps. Solid-state amps utilize a semiconductor instead of a tube to amplify the signal. Usually 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. In terms of harmonic distortion, class-A amps rank highest among all types of audio amplifiers. These amps also typically exhibit quite low noise. As such class-A amps are perfect for quite demanding applications in which low distortion and low noise are essential. However, similar to tube amplifiers, class-A amps have quite low power efficiency and most of the power is wasted.
Class-AB amps improve on the efficiency of class-A amps. They utilize a number of transistors in order to split up the large-level signals into two distinct areas, each of which can be amplified more efficiently. Because of the larger efficiency, class-AB amplifiers do not require the same amount of heat sinks as class-A amplifiers. Consequently they can be manufactured lighter and less expensive. Nonetheless, this topology adds some non-linearity or distortion in the region where the signal switches between those areas. As such class-AB amps usually have higher distortion than class-A amps.
Class-D amps improve on the efficiency of class-AB amplifiers even further by making use of a switching transistor that is constantly being switched on or off. Thereby this switching stage barely dissipates any power and consequently the power efficiency of class-D amps usually surpasses 90%. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component that has 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 kinds of amplifiers.
Newer amplifiers incorporate internal audio feedback in order to minimize the amount of music distortion. One type of audio amplifiers which makes use of this kind of feedback is known as "class-T" or "t amplifier". 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 extremely small.
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