Power amps are at the very center of every home theater product. As the quality and output power demands of modern speakers increase, so do the requirements of music amps. With the ever increasing number of models and design topologies, such as "tube amps", "class-A", "class-D" in addition to "t amp" types, it is getting more and more difficult to select the amp which is perfect for a particular application. This article is going to describe some of the most common terms and clarify some of the technical jargon that amplifier manufacturers often use.
Tube amplifiers were frequently used a few decades ago and use a vacuum tube that controls a high-voltage signal in accordance to a low-voltage control signal. Tubes, however, are nonlinear in their behavior and are going to introduce a rather large amount of higher harmonics or distortion. Nowadays, tube amplifiers still have many followers. The primary reason is that the distortion that tubes produce are often perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold".
A couple of decades ago, the most widespread type of audio amplifier were tube amps. Tube amplifiers utilize 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 transformed into a high-level signal. One drawback with tubes is that they are not extremely linear whilst amplifying signals. Aside from the original audio, there are going to be overtones or higher harmonics present in the amplified signal. Hence tube amps have rather high distortion. A lot of people favor tube amps because those higher harmonics are often perceived as the tube amplifier sounding "warm" or "pleasant".
The first generation versions of solid state amps are known as "Class-A" amps. Solid-state amps employ a semiconductor instead of a tube to amplify the signal. Usually bipolar transistors or FETs are being utilized. In class-A amps a transistor controls the current flow according to a small-level signal. A few amps utilize a feedback mechanism in order to reduce the harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest amid all kinds of music amplifiers. These amplifiers also usually exhibit quite low noise. As such class-A amps are perfect for quite demanding applications in which low distortion and low noise are essential. Class-A amplifiers, however, waste the majority of the energy as heat. Consequently they frequently have big heat sinks and are quite heavy.
Solid-state amplifiers utilize a semiconductor element, such as a bipolar transistor or FET instead of the tube and the earliest kind 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. If you need an ultra-low distortion amplifier then you may want to explore class-A amplifiers since they provide amongst the smallest distortion of any audio amps. Class-A amplifiers, however, waste most of the power as heat. As a result they frequently have big heat sinks and are quite heavy.
To further improve the audio efficiency, "class-D" amps utilize a switching stage which is constantly switched between two states: on or off. None of these two states dissipates energy inside the transistor. As a result, class-D amplifiers regularly are able to attain power efficiencies beyond 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered in order to remove the switching signal and recover the music signal. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amps exhibiting larger audio distortion than other types of amps.
Class-D amps improve on the efficiency of class-AB amps even further by making use of a switching transistor that is always being switched on or off. Thus this switching stage hardly dissipates any energy and thereby the power efficiency of class-D amps usually exceeds 90%. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Usual switching frequencies are in the range of 300 kHz and 1 MHz. This high-frequency switching signal has to be removed from the amplified signal by a lowpass filter. Commonly a simple first-order lowpass is being utilized. 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. Newer amps include internal audio feedback to minimize the level of music distortion. One kind of audio amplifiers which utilizes this kind of feedback is known as "class-T" or "t amp". Class-T amplifiers feed back the high-level switching signal to the audio signal processor for comparison. These amplifiers have low audio distortion and can be manufactured very small.
Tube amplifiers were frequently used a few decades ago and use a vacuum tube that controls a high-voltage signal in accordance to a low-voltage control signal. Tubes, however, are nonlinear in their behavior and are going to introduce a rather large amount of higher harmonics or distortion. Nowadays, tube amplifiers still have many followers. The primary reason is that the distortion that tubes produce are often perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold".
A couple of decades ago, the most widespread type of audio amplifier were tube amps. Tube amplifiers utilize 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 transformed into a high-level signal. One drawback with tubes is that they are not extremely linear whilst amplifying signals. Aside from the original audio, there are going to be overtones or higher harmonics present in the amplified signal. Hence tube amps have rather high distortion. A lot of people favor tube amps because those higher harmonics are often perceived as the tube amplifier sounding "warm" or "pleasant".
The first generation versions of solid state amps are known as "Class-A" amps. Solid-state amps employ a semiconductor instead of a tube to amplify the signal. Usually bipolar transistors or FETs are being utilized. In class-A amps a transistor controls the current flow according to a small-level signal. A few amps utilize a feedback mechanism in order to reduce the harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest amid all kinds of music amplifiers. These amplifiers also usually exhibit quite low noise. As such class-A amps are perfect for quite demanding applications in which low distortion and low noise are essential. Class-A amplifiers, however, waste the majority of the energy as heat. Consequently they frequently have big heat sinks and are quite heavy.
Solid-state amplifiers utilize a semiconductor element, such as a bipolar transistor or FET instead of the tube and the earliest kind 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. If you need an ultra-low distortion amplifier then you may want to explore class-A amplifiers since they provide amongst the smallest distortion of any audio amps. Class-A amplifiers, however, waste most of the power as heat. As a result they frequently have big heat sinks and are quite heavy.
To further improve the audio efficiency, "class-D" amps utilize a switching stage which is constantly switched between two states: on or off. None of these two states dissipates energy inside the transistor. As a result, class-D amplifiers regularly are able to attain power efficiencies beyond 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered in order to remove the switching signal and recover the music signal. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amps exhibiting larger audio distortion than other types of amps.
Class-D amps improve on the efficiency of class-AB amps even further by making use of a switching transistor that is always being switched on or off. Thus this switching stage hardly dissipates any energy and thereby the power efficiency of class-D amps usually exceeds 90%. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Usual switching frequencies are in the range of 300 kHz and 1 MHz. This high-frequency switching signal has to be removed from the amplified signal by a lowpass filter. Commonly a simple first-order lowpass is being utilized. 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. Newer amps include internal audio feedback to minimize the level of music distortion. One kind of audio amplifiers which utilizes this kind of feedback is known as "class-T" or "t amp". Class-T amplifiers feed back the high-level switching signal to the audio signal processor for comparison. These amplifiers have low audio distortion and can be manufactured very small.
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