Audio amplifiers are at the very core of each home theater system. As the quality and output power demands of today's speakers increase, so do the requirements of power amplifiers. With the ever increasing quantity of models and design topologies, including "tube amplifiers", "class-A", "class-D" as well as "t amp" designs, it is becoming more and more demanding to select the amplifier that is best for a particular application. This guide will explain a few of the most widespread terms and spell out a few of the technical jargon which amp suppliers frequently use.
The main operating principle of an audio amplifier is fairly clear-cut. An audio amplifier is going to take a low-level music signal. This signal typically originates from a source with a fairly large impedance. It subsequently converts this signal into a large-level signal. This large-level signal can also drive speakers with small impedance. Depending on the kind of amp, one of several kinds of elements are used in order to amplify the signal such as tubes as well as transistors.
Tube amplifiers used to be common several decades ago. A tube is able to control the current flow according to a control voltage that is connected to the tube. Tubes, though, are nonlinear in their behavior and will introduce a rather large amount of higher harmonics or distortion. Today, tube amplifiers still have many fans. The primary reason is that the distortion which tubes bring about are often perceived as "warm" or "pleasant". Solid state amps with low distortion, on the other hand, are perceived as "cold". Furthermore, tube amplifiers have rather low power efficiency and thereby dissipate a lot of power as heat. Tube amps, on the other hand, a rather costly to make and thus tube amps have mostly been replaced with amps utilizing transistor elements that are less costly to build.
Solid state amplifiers replace the tube with semiconductor elements, typically bipolar transistors or FETs. The earliest kind of solid-state amplifiers is often known as class-A amplifiers. In class-A amps a transistor controls the current flow according to a small-level signal. A number of amps utilize a feedback mechanism to reduce the harmonic distortion. If you require an ultra-low distortion amplifier then you might want to explore class-A amps since they offer amongst the lowest distortion of any audio amplifiers. The major downside is that much like tube amplifiers class A amps have quite small efficiency. Because of this these amplifiers require large heat sinks in order to radiate the wasted energy and are typically fairly heavy.
The first generation types of solid state amplifiers are generally known as "Class-A" amps. Solid-state amplifiers make use of a semiconductor instead of a tube to amplify the signal. Generally bipolar transistors or FETs are being used. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps utilize a feedback mechanism to minimize the harmonic distortion. Regarding harmonic distortion, class-A amplifiers rank highest amongst all types of power amplifiers. These amps also regularly exhibit very low noise. As such class-A amps are perfect for extremely demanding applications in which low distortion and low noise are crucial. Yet, similar to tube amplifiers, class-A amplifiers have very small power efficiency and the majority of the power is wasted.
Class-AB amplifiers improve on the efficiency of class-A amps. They employ a series of transistors in order to split up the large-level signals into two distinct regions, each of which can be amplified more efficiently. As such, class-AB amps are generally smaller than class-A amps. Class-AB amps have a drawback however. Each time the amplified signal transitions from one region to the other, there will be certain distortion produced. In other words the transition between these two areas is non-linear in nature. Therefore class-AB amps lack audio fidelity compared with 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. Thus this switching stage hardly dissipates any energy and therefore the power efficiency of class-D amps typically surpasses 90%. The switching transistor, which is being controlled by a pulse-width modulator generates a high-frequency switching component that has to be removed from the amplified signal by utilizing a lowpass filter. The switching transistor and also the pulse-width modulator typically exhibit fairly large non-linearities. As a consequence, the amplified signal is going to have some distortion. Class-D amplifiers by nature have higher audio distortion than other kinds of audio amps. More recent audio amplifiers incorporate some type of means to minimize distortion. One approach is to feed back the amplified music signal to the input of the amp in order to compare with the original signal. The difference signal is then utilized to correct the switching stage and compensate for the nonlinearity. One kind of audio amplifiers which utilizes this kind of feedback is called "class-T" or "t amplifier". Class-T amps feed back the high-level switching signal to the audio signal processor for comparison. These amps exhibit small audio distortion and can be manufactured extremely small.
The main operating principle of an audio amplifier is fairly clear-cut. An audio amplifier is going to take a low-level music signal. This signal typically originates from a source with a fairly large impedance. It subsequently converts this signal into a large-level signal. This large-level signal can also drive speakers with small impedance. Depending on the kind of amp, one of several kinds of elements are used in order to amplify the signal such as tubes as well as transistors.
Tube amplifiers used to be common several decades ago. A tube is able to control the current flow according to a control voltage that is connected to the tube. Tubes, though, are nonlinear in their behavior and will introduce a rather large amount of higher harmonics or distortion. Today, tube amplifiers still have many fans. The primary reason is that the distortion which tubes bring about are often perceived as "warm" or "pleasant". Solid state amps with low distortion, on the other hand, are perceived as "cold". Furthermore, tube amplifiers have rather low power efficiency and thereby dissipate a lot of power as heat. Tube amps, on the other hand, a rather costly to make and thus tube amps have mostly been replaced with amps utilizing transistor elements that are less costly to build.
Solid state amplifiers replace the tube with semiconductor elements, typically bipolar transistors or FETs. The earliest kind of solid-state amplifiers is often known as class-A amplifiers. In class-A amps a transistor controls the current flow according to a small-level signal. A number of amps utilize a feedback mechanism to reduce the harmonic distortion. If you require an ultra-low distortion amplifier then you might want to explore class-A amps since they offer amongst the lowest distortion of any audio amplifiers. The major downside is that much like tube amplifiers class A amps have quite small efficiency. Because of this these amplifiers require large heat sinks in order to radiate the wasted energy and are typically fairly heavy.
The first generation types of solid state amplifiers are generally known as "Class-A" amps. Solid-state amplifiers make use of a semiconductor instead of a tube to amplify the signal. Generally bipolar transistors or FETs are being used. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps utilize a feedback mechanism to minimize the harmonic distortion. Regarding harmonic distortion, class-A amplifiers rank highest amongst all types of power amplifiers. These amps also regularly exhibit very low noise. As such class-A amps are perfect for extremely demanding applications in which low distortion and low noise are crucial. Yet, similar to tube amplifiers, class-A amplifiers have very small power efficiency and the majority of the power is wasted.
Class-AB amplifiers improve on the efficiency of class-A amps. They employ a series of transistors in order to split up the large-level signals into two distinct regions, each of which can be amplified more efficiently. As such, class-AB amps are generally smaller than class-A amps. Class-AB amps have a drawback however. Each time the amplified signal transitions from one region to the other, there will be certain distortion produced. In other words the transition between these two areas is non-linear in nature. Therefore class-AB amps lack audio fidelity compared with 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. Thus this switching stage hardly dissipates any energy and therefore the power efficiency of class-D amps typically surpasses 90%. The switching transistor, which is being controlled by a pulse-width modulator generates a high-frequency switching component that has to be removed from the amplified signal by utilizing a lowpass filter. The switching transistor and also the pulse-width modulator typically exhibit fairly large non-linearities. As a consequence, the amplified signal is going to have some distortion. Class-D amplifiers by nature have higher audio distortion than other kinds of audio amps. More recent audio amplifiers incorporate some type of means to minimize distortion. One approach is to feed back the amplified music signal to the input of the amp in order to compare with the original signal. The difference signal is then utilized to correct the switching stage and compensate for the nonlinearity. One kind of audio amplifiers which utilizes this kind of feedback is called "class-T" or "t amplifier". Class-T amps feed back the high-level switching signal to the audio signal processor for comparison. These amps exhibit small audio distortion and can be manufactured extremely small.
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