A Short Comparison Of Power Amps
None of recent audio products would be possible lacking the help of latest power amps which strive to satisfy higher and higher requirements regarding power and audio fidelity. With the ever increasing quantity of models and design topologies, such as "tube amps", "class-A", "class-D" along with "t amplifier" types, it is getting more and more complex to choose the amp which is ideal for a specific application. This guide is going to describe a few of the most popular terms and clarify some of the technical jargon that amp makers regularly utilize.
Simply put, the principle of an audio amplifier is to convert a low-power music signal into a high-power music signal. The high-power signal is great enough to drive a loudspeaker adequately loud. Determined by the kind of amplifier, one of several kinds of elements are used to amplify the signal including tubes and transistors.
Tube amplifiers used to be popular several decades ago. A tube is able to control the current flow according to a control voltage which is attached to the tube. One drawback with tubes is that they are not very linear when amplifying signals. Aside from the original audio, there will be overtones or higher harmonics present in the amplified signal. Consequently tube amps have quite large distortion. These days, tube amplifiers still have many fans. The main reason is that the distortion which tubes produce are often perceived as "warm" or "pleasant". Solid state amplifiers with small distortion, on the other hand, are perceived as "cold".
The first generation types 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. Generally bipolar transistors or FETs are being utilized. 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 minimize the harmonic distortion. If you require an ultra-low distortion amp then you may want to explore class-A amps since they provide amongst the smallest distortion of any audio amps. Class-A amplifiers, on the other hand, waste most of the energy as heat. For that reason they typically have large heat sinks and are fairly bulky.
To improve on the low efficiency of class-A amplifiers, class-AB amplifiers utilize a series of transistors which each amplify a distinct area, each of which being more efficient than class-A amplifiers. As a result of the higher efficiency, class-AB amplifiers do not require the same amount of heat sinks as class-A amplifiers. For that reason they can be made lighter and less costly. Nonetheless, this topology adds some non-linearity or distortion in the region where the signal switches between those areas. As such class-AB amplifiers typically have larger distortion than class-A amplifiers.
Class-D amplifiers are able to achieve power efficiencies higher than 90% by employing a switching transistor that is continually being switched on and off and therefore the transistor itself does not dissipate any heat. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal has to be lowpass filtered to remove the switching signal and get back the audio signal. 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.
In order to resolve the problem of high music distortion, new switching amp styles incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. A well-known topology that utilizes this type of feedback is known as "class-T". Class-T amps or "t amps" achieve audio distortion that compares with the audio distortion of class-A amps while at the same time offering the power efficiency of class-D amps. Therefore t amps can be made extremely small and still achieve high audio fidelity.
Simply put, the principle of an audio amplifier is to convert a low-power music signal into a high-power music signal. The high-power signal is great enough to drive a loudspeaker adequately loud. Determined by the kind of amplifier, one of several kinds of elements are used to amplify the signal including tubes and transistors.
Tube amplifiers used to be popular several decades ago. A tube is able to control the current flow according to a control voltage which is attached to the tube. One drawback with tubes is that they are not very linear when amplifying signals. Aside from the original audio, there will be overtones or higher harmonics present in the amplified signal. Consequently tube amps have quite large distortion. These days, tube amplifiers still have many fans. The main reason is that the distortion which tubes produce are often perceived as "warm" or "pleasant". Solid state amplifiers with small distortion, on the other hand, are perceived as "cold".
The first generation types 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. Generally bipolar transistors or FETs are being utilized. 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 minimize the harmonic distortion. If you require an ultra-low distortion amp then you may want to explore class-A amps since they provide amongst the smallest distortion of any audio amps. Class-A amplifiers, on the other hand, waste most of the energy as heat. For that reason they typically have large heat sinks and are fairly bulky.
To improve on the low efficiency of class-A amplifiers, class-AB amplifiers utilize a series of transistors which each amplify a distinct area, each of which being more efficient than class-A amplifiers. As a result of the higher efficiency, class-AB amplifiers do not require the same amount of heat sinks as class-A amplifiers. For that reason they can be made lighter and less costly. Nonetheless, this topology adds some non-linearity or distortion in the region where the signal switches between those areas. As such class-AB amplifiers typically have larger distortion than class-A amplifiers.
Class-D amplifiers are able to achieve power efficiencies higher than 90% by employing a switching transistor that is continually being switched on and off and therefore the transistor itself does not dissipate any heat. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal has to be lowpass filtered to remove the switching signal and get back the audio signal. 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.
In order to resolve the problem of high music distortion, new switching amp styles incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. A well-known topology that utilizes this type of feedback is known as "class-T". Class-T amps or "t amps" achieve audio distortion that compares with the audio distortion of class-A amps while at the same time offering the power efficiency of class-D amps. Therefore t amps can be made extremely small and still achieve high audio fidelity.
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