Demands concerning audio power and audio fidelity of today's speakers and home theater systems are always increasing. At the core of those products is the audio amp. Modern audio amplifiers have to perform well enough to meet those ever growing requirements. It is tough to choose an amp given the big number of types and concepts. I am going to clarify some of the most common amp designs including "tube amps", "linear amps", "class-AB" and "class-D" and also "class-T amps" to help you comprehend a few of the terms regularly utilized by amp suppliers. This article should also help you figure out what topology is ideal for your specific application.
An audio amplifier will translate a low-level audio signal that often comes from a high-impedance source into a high-level signal that can drive a loudspeaker with a low impedance. As a way to do that, an amp employs one or several 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.
Several decades ago, the most common kind of audio amplifier were tube amps. Tube amplifiers 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. Unfortunately, tube amplifiers have a fairly high level of distortion. Technically speaking, tube amps are going to introduce higher harmonics into the signal. These days, tube amps still have many followers. The most important reason is that the distortion which tubes produce are frequently perceived as "warm" or "pleasant". Solid state amplifiers with small distortion, on the other hand, are perceived as "cold".
Solid-state amplifiers utilize a semiconductor element, like a bipolar transistor or FET rather than the tube and the earliest sort is known as "class-A" amps. 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 amplifiers rank highest among all types of audio amplifiers. These amplifiers also regularly exhibit quite low noise. As such class-A amplifiers are perfect for quite demanding applications in which low distortion and low noise are vital. Class-A amps, on the other hand, waste the majority of the energy as heat. Consequently they usually have big heat sinks and are fairly heavy.
The first generation types of solid state amplifiers are often known as "Class-A" amps. Solid-state amplifiers use a semiconductor instead of a tube to amplify the signal. Typically bipolar transistors or FETs are being used. The working principle of class-A amps is very similar to that of tube amps. The primary difference is that a transistor is being utilized instead of the tube for amplifying the music signal. The amplified high-level signal is sometimes fed back to minimize harmonic distortion. If you need an ultra-low distortion amp then you might wish to explore class-A amplifiers as they provide amongst the lowest distortion of any audio amplifiers. Class-A amplifiers, on the other hand, waste most of the power as heat. Consequently they typically have big heat sinks and are fairly heavy.
By using a series of transistors, class-AB amplifiers improve on the small power efficiency of class-A amps. The operating area is split into two distinct areas. These 2 regions are handled by separate transistors. Each of those transistors operates more efficiently than the single transistor in a class-A amp. As such, class-AB amplifiers are typically smaller than class-A amplifiers. Class-AB amplifiers have a disadvantage however. Each time the amplified signal transitions from a region to the other, there will be certain distortion generated. In other words the transition between these 2 areas is non-linear in nature. As a result class-AB amplifiers lack audio fidelity compared with class-A amps.
Class-D amplifiers are able to attain power efficiencies above 90% by employing a switching transistor that is constantly being switched on and off and therefore the transistor itself does not dissipate any heat. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component that needs to be removed from the amplified signal by making use of 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 largest audio distortion of any audio amp. More modern audio amps incorporate some sort of mechanism to minimize distortion. One method is to feed back the amplified music signal to the input of the amplifier in order to compare with the original signal. The difference signal is subsequently used in order to correct the switching stage and compensate for the nonlinearity. One kind of audio amps that uses this kind 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 amps exhibit small music distortion and can be manufactured extremely small.
An audio amplifier will translate a low-level audio signal that often comes from a high-impedance source into a high-level signal that can drive a loudspeaker with a low impedance. As a way to do that, an amp employs one or several 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.
Several decades ago, the most common kind of audio amplifier were tube amps. Tube amplifiers 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. Unfortunately, tube amplifiers have a fairly high level of distortion. Technically speaking, tube amps are going to introduce higher harmonics into the signal. These days, tube amps still have many followers. The most important reason is that the distortion which tubes produce are frequently perceived as "warm" or "pleasant". Solid state amplifiers with small distortion, on the other hand, are perceived as "cold".
Solid-state amplifiers utilize a semiconductor element, like a bipolar transistor or FET rather than the tube and the earliest sort is known as "class-A" amps. 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 amplifiers rank highest among all types of audio amplifiers. These amplifiers also regularly exhibit quite low noise. As such class-A amplifiers are perfect for quite demanding applications in which low distortion and low noise are vital. Class-A amps, on the other hand, waste the majority of the energy as heat. Consequently they usually have big heat sinks and are fairly heavy.
The first generation types of solid state amplifiers are often known as "Class-A" amps. Solid-state amplifiers use a semiconductor instead of a tube to amplify the signal. Typically bipolar transistors or FETs are being used. The working principle of class-A amps is very similar to that of tube amps. The primary difference is that a transistor is being utilized instead of the tube for amplifying the music signal. The amplified high-level signal is sometimes fed back to minimize harmonic distortion. If you need an ultra-low distortion amp then you might wish to explore class-A amplifiers as they provide amongst the lowest distortion of any audio amplifiers. Class-A amplifiers, on the other hand, waste most of the power as heat. Consequently they typically have big heat sinks and are fairly heavy.
By using a series of transistors, class-AB amplifiers improve on the small power efficiency of class-A amps. The operating area is split into two distinct areas. These 2 regions are handled by separate transistors. Each of those transistors operates more efficiently than the single transistor in a class-A amp. As such, class-AB amplifiers are typically smaller than class-A amplifiers. Class-AB amplifiers have a disadvantage however. Each time the amplified signal transitions from a region to the other, there will be certain distortion generated. In other words the transition between these 2 areas is non-linear in nature. As a result class-AB amplifiers lack audio fidelity compared with class-A amps.
Class-D amplifiers are able to attain power efficiencies above 90% by employing a switching transistor that is constantly being switched on and off and therefore the transistor itself does not dissipate any heat. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component that needs to be removed from the amplified signal by making use of 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 largest audio distortion of any audio amp. More modern audio amps incorporate some sort of mechanism to minimize distortion. One method is to feed back the amplified music signal to the input of the amplifier in order to compare with the original signal. The difference signal is subsequently used in order to correct the switching stage and compensate for the nonlinearity. One kind of audio amps that uses this kind 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 amps exhibit small music distortion and can be manufactured extremely small.
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