None of today's audio systems would be achievable without the aid of recent music amplifiers that strive to satisfy higher and higher demands concerning power and audio fidelity. There is a large amount of amplifier designs and models. All of these differ when it comes to performance. I am going to explain some of the most popular amp terms like "class-A", "class-D" and "t amps" to help you figure out which of these amps is best for your application. Moreover, after reading this guide you should be able to comprehend the amp specs that makers publish.
The basic operating principle of an audio amp is rather simple. An audio amp is going to take a low-level music signal. This signal typically originates from a source with a comparatively high impedance. It then converts this signal into a large-level signal. This large-level signal may also drive speakers with small impedance. The type of element utilized to amplify the signal is dependent on which amp architecture is utilized. Some amps even utilize several types of elements. Typically the following parts are utilized: tubes, bipolar transistors plus FETs.
Besides, tube amplifiers have rather low power efficiency and consequently radiate a lot of power as heat. Moreover, tubes are quite expensive to manufacture. Therefore tube amps have generally been replaced by solid-state amps which I am going to look at next.
An additional drawback of tube amplifiers, however, is the small power efficiency. The majority of power which tube amps consume is being dissipated as heat and merely a portion is being transformed into audio power. Moreover, tubes are fairly costly to build. As a result tube amps have generally been replaced by solid-state amps which I am going to look at next.
In order to improve on the small efficiency of class-A amplifiers, class-AB amps utilize a number of transistors that each amplify a separate area, each of which being more efficient than class-A amplifiers. As such, class-AB amplifiers are generally smaller than class-A amps. Class-AB amplifiers have a downside though. Every time the amplified signal transitions from one region to the other, there will be certain distortion generated. In other words the transition between these two areas is non-linear in nature. Therefore class-AB amplifiers lack audio fidelity compared with class-A amps.
By employing a number of transistors, class-AB amps improve on the small power efficiency of class-A amplifiers. The operating region is split into two separate areas. These 2 areas are handled by separate transistors. Each of these transistors operates more efficiently than the single transistor in a class-A amplifier. The larger efficiency of class-AB amplifiers also has 2 other advantages. First of all, the necessary amount of heat sinking is reduced. Consequently class-AB amplifiers can be made lighter and smaller. For that reason, class-AB amps can be manufactured cheaper than class-A amplifiers. When the signal transitions between the two separate areas, though, a certain level of distortion is being created, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amplifiers.
Class-D amplifiers improve on the efficiency of class-AB amplifiers even further by employing a switching transistor that is always being switched on or off. Thus this switching stage hardly dissipates any power and consequently 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). Typical switching frequencies are in the range of 300 kHz and 1 MHz. This high-frequency switching signal needs to be removed from the amplified signal by a lowpass filter. Normally a simple first-order lowpass is being utilized. The switching transistor and in addition the pulse-width modulator typically have rather large non-linearities. As a consequence, the amplified signal is going to contain some distortion. Class-D amplifiers by nature have larger audio distortion than other types of audio amplifiers. More recent audio amps include some sort of means to minimize distortion. One method is to feed back the amplified music signal to the input of the amp to compare with the original signal. The difference signal is then utilized to correct the switching stage and compensate for the nonlinearity. One type of audio amplifiers which utilizes this kind of feedback is known as "class-T" or "t amp". 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 made extremely small.
The basic operating principle of an audio amp is rather simple. An audio amp is going to take a low-level music signal. This signal typically originates from a source with a comparatively high impedance. It then converts this signal into a large-level signal. This large-level signal may also drive speakers with small impedance. The type of element utilized to amplify the signal is dependent on which amp architecture is utilized. Some amps even utilize several types of elements. Typically the following parts are utilized: tubes, bipolar transistors plus FETs.
Besides, tube amplifiers have rather low power efficiency and consequently radiate a lot of power as heat. Moreover, tubes are quite expensive to manufacture. Therefore tube amps have generally been replaced by solid-state amps which I am going to look at next.
An additional drawback of tube amplifiers, however, is the small power efficiency. The majority of power which tube amps consume is being dissipated as heat and merely a portion is being transformed into audio power. Moreover, tubes are fairly costly to build. As a result tube amps have generally been replaced by solid-state amps which I am going to look at next.
In order to improve on the small efficiency of class-A amplifiers, class-AB amps utilize a number of transistors that each amplify a separate area, each of which being more efficient than class-A amplifiers. As such, class-AB amplifiers are generally smaller than class-A amps. Class-AB amplifiers have a downside though. Every time the amplified signal transitions from one region to the other, there will be certain distortion generated. In other words the transition between these two areas is non-linear in nature. Therefore class-AB amplifiers lack audio fidelity compared with class-A amps.
By employing a number of transistors, class-AB amps improve on the small power efficiency of class-A amplifiers. The operating region is split into two separate areas. These 2 areas are handled by separate transistors. Each of these transistors operates more efficiently than the single transistor in a class-A amplifier. The larger efficiency of class-AB amplifiers also has 2 other advantages. First of all, the necessary amount of heat sinking is reduced. Consequently class-AB amplifiers can be made lighter and smaller. For that reason, class-AB amps can be manufactured cheaper than class-A amplifiers. When the signal transitions between the two separate areas, though, a certain level of distortion is being created, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amplifiers.
Class-D amplifiers improve on the efficiency of class-AB amplifiers even further by employing a switching transistor that is always being switched on or off. Thus this switching stage hardly dissipates any power and consequently 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). Typical switching frequencies are in the range of 300 kHz and 1 MHz. This high-frequency switching signal needs to be removed from the amplified signal by a lowpass filter. Normally a simple first-order lowpass is being utilized. The switching transistor and in addition the pulse-width modulator typically have rather large non-linearities. As a consequence, the amplified signal is going to contain some distortion. Class-D amplifiers by nature have larger audio distortion than other types of audio amplifiers. More recent audio amps include some sort of means to minimize distortion. One method is to feed back the amplified music signal to the input of the amp to compare with the original signal. The difference signal is then utilized to correct the switching stage and compensate for the nonlinearity. One type of audio amplifiers which utilizes this kind of feedback is known as "class-T" or "t amp". 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 made extremely small.
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