None of recent music products would be achievable without the help of recent stereo amps which try to satisfy higher and higher demands regarding power and music fidelity. It is tricky to pick an amplifier given the large range of models and concepts. I am going to clarify a few of the most popular amplifier designs including "tube amplifiers", "linear amplifiers", "class-AB" and "class-D" and also "class-T amps" to help you understand some of the terms commonly utilized by amp producers. This essay should also help you figure out what topology is best for your specific application.
Tube amplifiers were frequently used a couple of decades ago and utilize a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. One problem with tubes is that they are not extremely linear while amplifying signals. Aside from the original audio, there are going to be overtones or higher harmonics present in the amplified signal. Therefore tube amps have rather high distortion. A lot of people prefer tube amplifiers because those higher harmonics are frequently perceived as the tube amp sounding "warm" or "pleasant".
Tube amplifiers were frequently used a number of decades ago and use a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Tubes, on the other hand, are nonlinear in their behavior and will introduce a rather large level of higher harmonics or distortion. However, this characteristic of tube amplifiers still makes these popular. A lot of people describe tube amps as having a warm sound versus the cold sound of solid state amps.
Solid-state amplifiers utilize a semiconductor element, like a bipolar transistor or FET as opposed to the tube and the first type is often known as "class-A" amps. The working principle of class-A amplifiers is very similar to that of tube amplifiers. The main difference is that a transistor is being used instead of the tube for amplifying the music signal. The amplified high-level signal is at times fed back in order to minimize harmonic distortion. Regarding harmonic distortion, class-A amps rank highest among all kinds of power amps. These amps also typically exhibit very low noise. As such class-A amplifiers are perfect for very demanding applications in which low distortion and low noise are important. Class-A amplifiers, however, waste the majority of the power as heat. Therefore they frequently have large heat sinks and are quite bulky.
By making use of a number of transistors, class-AB amplifiers improve on the small power efficiency of class-A amplifiers. The operating region is split into two separate areas. These 2 regions are handled by separate transistors. Each of those transistors works more efficiently than the single transistor in a class-A amplifier. As such, class-AB amps are usually smaller than class-A amplifiers. When the signal transitions between the 2 separate regions, however, a certain amount of distortion is being produced, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amps.
To further improve the audio efficiency, "class-D" amplifiers employ a switching stage which is constantly switched between 2 states: on or off. None of these 2 states dissipates energy within the transistor. Consequently, class-D amplifiers frequently are able to achieve power efficiencies beyond 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 largest audio distortion of any audio amp.
More recent audio amplifiers incorporate some kind of means in order to minimize distortion. One method 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 to correct the switching stage and compensate for the nonlinearity. One type of audio amps that makes use of this type of feedback is known as "class-T" or "t amplifier". Class-T amps feed back the high-level switching signal to the audio signal processor for comparison. These amps have low audio distortion and can be manufactured extremely small.
Tube amplifiers were frequently used a couple of decades ago and utilize a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. One problem with tubes is that they are not extremely linear while amplifying signals. Aside from the original audio, there are going to be overtones or higher harmonics present in the amplified signal. Therefore tube amps have rather high distortion. A lot of people prefer tube amplifiers because those higher harmonics are frequently perceived as the tube amp sounding "warm" or "pleasant".
Tube amplifiers were frequently used a number of decades ago and use a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Tubes, on the other hand, are nonlinear in their behavior and will introduce a rather large level of higher harmonics or distortion. However, this characteristic of tube amplifiers still makes these popular. A lot of people describe tube amps as having a warm sound versus the cold sound of solid state amps.
Solid-state amplifiers utilize a semiconductor element, like a bipolar transistor or FET as opposed to the tube and the first type is often known as "class-A" amps. The working principle of class-A amplifiers is very similar to that of tube amplifiers. The main difference is that a transistor is being used instead of the tube for amplifying the music signal. The amplified high-level signal is at times fed back in order to minimize harmonic distortion. Regarding harmonic distortion, class-A amps rank highest among all kinds of power amps. These amps also typically exhibit very low noise. As such class-A amplifiers are perfect for very demanding applications in which low distortion and low noise are important. Class-A amplifiers, however, waste the majority of the power as heat. Therefore they frequently have large heat sinks and are quite bulky.
By making use of a number of transistors, class-AB amplifiers improve on the small power efficiency of class-A amplifiers. The operating region is split into two separate areas. These 2 regions are handled by separate transistors. Each of those transistors works more efficiently than the single transistor in a class-A amplifier. As such, class-AB amps are usually smaller than class-A amplifiers. When the signal transitions between the 2 separate regions, however, a certain amount of distortion is being produced, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amps.
To further improve the audio efficiency, "class-D" amplifiers employ a switching stage which is constantly switched between 2 states: on or off. None of these 2 states dissipates energy within the transistor. Consequently, class-D amplifiers frequently are able to achieve power efficiencies beyond 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 largest audio distortion of any audio amp.
More recent audio amplifiers incorporate some kind of means in order to minimize distortion. One method 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 to correct the switching stage and compensate for the nonlinearity. One type of audio amps that makes use of this type of feedback is known as "class-T" or "t amplifier". Class-T amps feed back the high-level switching signal to the audio signal processor for comparison. These amps have low audio distortion and can be manufactured extremely small.
No comments:
Post a Comment