Audio amplifiers are at the very center of each home theater product. As the quality and output power demands of modern loudspeakers increase, so do the requirements of stereo amps. There is a huge amount of amplifier designs and models. All of these differ regarding performance. I am going to describe a few of the most common amp terms such as "class-A", "class-D" and "t amps" to help you figure out which of these amplifiers is ideal for your application. Also, after reading this essay you should be able to comprehend the amplifier specs which manufacturers show. The fundamental operating principle of an audio amp is quite simple. An audio amp will take a low-level music signal. This signal typically comes from a source with a comparatively high impedance. It subsequently translates this signal into a large-level signal. This large-level signal may also drive speakers with low impedance. Determined by the kind of amp, one of several types of elements are utilized in order to amplify the signal like tubes and transistors.
An audio amp will convert a low-level music signal that often originates from a high-impedance source into a high-level signal which may drive a speaker with a low impedance. As a way to do that, an amp utilizes one or several elements that are controlled by the low-power signal to generate a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
Tube amps used to be widespread a number of decades ago. A tube is able to control the current flow in accordance to a control voltage which is attached to the tube. Tubes, on the other hand, are nonlinear in their behavior and are going to introduce a quite large amount of higher harmonics or distortion. Many people favor tube amps because those higher harmonics are frequently perceived as the tube amplifier sounding "warm" or "pleasant". Also, tube amplifiers have fairly low power efficiency and thus radiate much power as heat. Tube amps, though, a quite expensive to produce and for that reason tube amps have by and large been replaced with amps making use of transistor elements that are less expensive to make.
A drawback of tube amps is their low power efficiency. In other words, the majority of the power consumed by the amp is wasted as heat as opposed to being converted into music. Consequently tube amplifiers are going to run hot and need adequate cooling. In addition, tubes are fairly expensive to produce. Consequently tube amplifiers have generally been replaced by solid-state amplifiers which I will look at next.
To improve on the low efficiency of class-A amps, class-AB amplifiers employ a series of transistors that each amplify a distinct area, each of which being more efficient than class-A amps. Due to the larger efficiency, class-AB amplifiers do not require the same number of heat sinks as class-A amps. For that reason they can be made lighter and cheaper. Though, this topology adds some non-linearity or distortion in the region where the signal switches between those regions. As such class-AB amplifiers generally have larger distortion than class-A amps.
In order to further improve the audio efficiency, "class-D" amplifiers use a switching stage which is constantly switched between 2 states: on or off. None of these 2 states dissipates energy inside the transistor. Consequently, class-D amplifiers frequently are able to attain power efficiencies higher than 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered to remove the switching signal and get back the audio signal. Both the pulse-width modulator and the transistor have non-linearities that result in class-D amps having larger music distortion than other types of amps.
In order to further improve the audio efficiency, "class-D" amps use a switching stage which is constantly switched between 2 states: on or off. None of these two states dissipates energy inside the transistor. Therefore, class-D amps frequently are able to achieve power efficiencies higher than 90%. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component which has to be removed from the amplified signal by using 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 highest audio distortion of any audio amp. More recent audio amps include some type of mechanism to reduce distortion. One approach is to feed back the amplified audio signal to the input of the amplifier 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 amplifiers which employs this type 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 amps have small music distortion and can be manufactured extremely small.
An audio amp will convert a low-level music signal that often originates from a high-impedance source into a high-level signal which may drive a speaker with a low impedance. As a way to do that, an amp utilizes one or several elements that are controlled by the low-power signal to generate a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
Tube amps used to be widespread a number of decades ago. A tube is able to control the current flow in accordance to a control voltage which is attached to the tube. Tubes, on the other hand, are nonlinear in their behavior and are going to introduce a quite large amount of higher harmonics or distortion. Many people favor tube amps because those higher harmonics are frequently perceived as the tube amplifier sounding "warm" or "pleasant". Also, tube amplifiers have fairly low power efficiency and thus radiate much power as heat. Tube amps, though, a quite expensive to produce and for that reason tube amps have by and large been replaced with amps making use of transistor elements that are less expensive to make.
A drawback of tube amps is their low power efficiency. In other words, the majority of the power consumed by the amp is wasted as heat as opposed to being converted into music. Consequently tube amplifiers are going to run hot and need adequate cooling. In addition, tubes are fairly expensive to produce. Consequently tube amplifiers have generally been replaced by solid-state amplifiers which I will look at next.
To improve on the low efficiency of class-A amps, class-AB amplifiers employ a series of transistors that each amplify a distinct area, each of which being more efficient than class-A amps. Due to the larger efficiency, class-AB amplifiers do not require the same number of heat sinks as class-A amps. For that reason they can be made lighter and cheaper. Though, this topology adds some non-linearity or distortion in the region where the signal switches between those regions. As such class-AB amplifiers generally have larger distortion than class-A amps.
In order to further improve the audio efficiency, "class-D" amplifiers use a switching stage which is constantly switched between 2 states: on or off. None of these 2 states dissipates energy inside the transistor. Consequently, class-D amplifiers frequently are able to attain power efficiencies higher than 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered to remove the switching signal and get back the audio signal. Both the pulse-width modulator and the transistor have non-linearities that result in class-D amps having larger music distortion than other types of amps.
In order to further improve the audio efficiency, "class-D" amps use a switching stage which is constantly switched between 2 states: on or off. None of these two states dissipates energy inside the transistor. Therefore, class-D amps frequently are able to achieve power efficiencies higher than 90%. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component which has to be removed from the amplified signal by using 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 highest audio distortion of any audio amp. More recent audio amps include some type of mechanism to reduce distortion. One approach is to feed back the amplified audio signal to the input of the amplifier 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 amplifiers which employs this type 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 amps have small music distortion and can be manufactured extremely small.
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