None of recent stereo systems would be possible lacking the aid of recent stereo amplifiers which strive to satisfy higher and higher demands regarding power and audio fidelity. There is a large amount of amplifier designs and types. All of these differ in terms of performance. I am going to describe some of the most popular amp terms such as "class-A", "class-D" and "t amps" to help you figure out which of these amps is ideal for your application. Furthermore, after understanding this guide you should be able to understand the amplifier specs which manufacturers issue.
The fundamental operating principle of an audio amplifier is rather simple. An audio amplifier is going to take a low-level audio signal. This signal typically comes from a source with a fairly high impedance. It subsequently translates this signal into a large-level signal. This large-level signal may also drive loudspeakers with low impedance. As a way to do that, an amplifier utilizes one or several elements which are controlled by the low-power signal in order to create a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
Tube amplifiers were commonly used several decades ago and employ a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Regrettably, tube amplifiers have a reasonably high level of distortion. Technically speaking, tube amplifiers are going to introduce higher harmonics into the signal. However, this characteristic of tube amps still makes these popular. A lot of people describe tube amps as having a warm sound as opposed to the cold sound of solid state amplifiers.
The first generation types of solid state amplifiers are generally known as "Class-A" amps. Solid-state amps utilize a semiconductor rather than a tube to amplify the signal. Regularly bipolar transistors or FETs are being used. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps make use of a feedback mechanism to reduce the harmonic distortion. If you require an ultra-low distortion amp then you may want to explore class-A amps as they provide amongst the lowest distortion of any audio amps. The main downside is that much like tube amps class A amps have quite small efficiency. Consequently these amplifiers need large heat sinks to dissipate the wasted energy and are typically rather large.
Class-AB amplifiers improve on the efficiency of class-A amps. They make use of a number of transistors to break up the large-level signals into 2 separate areas, each of which can be amplified more efficiently. As such, class-AB amps are usually smaller than class-A amplifiers. When the signal transitions between the two distinct areas, however, a certain amount of distortion is being produced, thereby class-AB amps will not achieve the same audio fidelity as class-A amplifiers.
To further improve the audio efficiency, "class-D" amps make use of a switching stage that is continually switched between two states: on or off. None of these 2 states dissipates energy inside the transistor. As a result, class-D amplifiers regularly are able to attain power efficiencies beyond 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. Usually a straightforward first-order lowpass is being utilized. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amps exhibiting larger music distortion than other types of amps.
New amps include internal audio feedback in order to minimize the level of music distortion. One kind of audio amps which makes use of 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 exhibit small audio distortion and can be manufactured very small.
The fundamental operating principle of an audio amplifier is rather simple. An audio amplifier is going to take a low-level audio signal. This signal typically comes from a source with a fairly high impedance. It subsequently translates this signal into a large-level signal. This large-level signal may also drive loudspeakers with low impedance. As a way to do that, an amplifier utilizes one or several elements which are controlled by the low-power signal in order to create a large-power signal. These elements range from tubes, bipolar transistors to FET transistors.
Tube amplifiers were commonly used several decades ago and employ a vacuum tube which controls a high-voltage signal in accordance to a low-voltage control signal. Regrettably, tube amplifiers have a reasonably high level of distortion. Technically speaking, tube amplifiers are going to introduce higher harmonics into the signal. However, this characteristic of tube amps still makes these popular. A lot of people describe tube amps as having a warm sound as opposed to the cold sound of solid state amplifiers.
The first generation types of solid state amplifiers are generally known as "Class-A" amps. Solid-state amps utilize a semiconductor rather than a tube to amplify the signal. Regularly bipolar transistors or FETs are being used. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps make use of a feedback mechanism to reduce the harmonic distortion. If you require an ultra-low distortion amp then you may want to explore class-A amps as they provide amongst the lowest distortion of any audio amps. The main downside is that much like tube amps class A amps have quite small efficiency. Consequently these amplifiers need large heat sinks to dissipate the wasted energy and are typically rather large.
Class-AB amplifiers improve on the efficiency of class-A amps. They make use of a number of transistors to break up the large-level signals into 2 separate areas, each of which can be amplified more efficiently. As such, class-AB amps are usually smaller than class-A amplifiers. When the signal transitions between the two distinct areas, however, a certain amount of distortion is being produced, thereby class-AB amps will not achieve the same audio fidelity as class-A amplifiers.
To further improve the audio efficiency, "class-D" amps make use of a switching stage that is continually switched between two states: on or off. None of these 2 states dissipates energy inside the transistor. As a result, class-D amplifiers regularly are able to attain power efficiencies beyond 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. Usually a straightforward first-order lowpass is being utilized. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amps exhibiting larger music distortion than other types of amps.
New amps include internal audio feedback in order to minimize the level of music distortion. One kind of audio amps which makes use of 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 exhibit small audio distortion and can be manufactured very small.