None of recent stereo systems would be possible without the help of modern stereo amplifiers which attempt to satisfy higher and higher requirements regarding power and audio fidelity. There is a large quantity of amp designs and types. All of these differ in terms of performance. I will explain some of the most popular amplifier terms including "class-A", "class-D" and "t amps" to help you figure out which of these amplifiers is ideal for your application. Moreover, after reading this article you should be able to comprehend the amplifier specifications that manufacturers publish.
The fundamental operating principle of an audio amplifier is fairly straightforward. An audio amp will take a low-level music signal. This signal usually originates from a source with a fairly large impedance. It then translates this signal into a large-level signal. This large-level signal can also drive loudspeakers with small impedance. Depending on the type of amplifier, one of several kinds of elements are utilized in order to amplify the signal such as tubes and transistors.
A couple of decades ago, the most widespread type of audio amp were tube amps. Tube amps use a tube as the amplifying element. The current flow through the tube is controlled by a low-level control signal. Thereby the low-level audio is transformed into a high-level signal. Tubes, though, are nonlinear in their behavior and will introduce a quite large amount of higher harmonics or distortion. A lot of people favor tube amplifiers since those higher harmonics are often perceived as the tube amplifier sounding "warm" or "pleasant". An additional downside of tube amplifiers, however, is the low power efficiency. The majority of power which tube amplifiers consume is being dissipated as heat and merely a portion is being transformed into audio power. Moreover, tubes are pretty costly to produce. Therefore tube amplifiers have by and large been replaced by solid-state amps which I will glance at next.
In addition, tube amps have fairly low power efficiency and therefore radiate a lot of power as heat. Yet one more downside is the high price tag of tubes. This has put tube amps out of the ballpark for many consumer devices. Consequently, the majority of audio products nowadays uses solid state amplifiers. I will describe solid state amps in the following paragraphs.
The first generation types of solid state amps are generally known as "Class-A" amps. Solid-state amps employ a semiconductor as opposed to a tube to amplify the signal. Typically bipolar transistors or FETs are being utilized. In a class-A amp, the signal is being amplified by a transistor which is controlled by the low-level audio signal. Class-A amps have the smallest distortion and usually also the lowest amount of noise of any amplifier architecture. If you require ultra-low distortion then you should take a closer look at class-A types. The major drawback is that just like tube amps class A amps have extremely low efficiency. Because of this these amplifiers require large heat sinks in order to dissipate the wasted energy and are usually rather heavy.
Class-D amplifiers improve on the efficiency of class-AB amplifiers even further by utilizing a switching transistor which is always being switched on or off. Thereby this switching stage barely dissipates any energy and thereby the power efficiency of class-D amps frequently exceeds 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal has to be lowpass filtered in order to remove the switching signal and recover the music signal. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amps exhibiting bigger audio distortion than other kinds of amplifiers.
Newer amps include internal audio feedback in order to minimize the amount of audio distortion. One kind of audio amps that makes use of this type of feedback is known as "class-T" or "t amplifier". 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 fairly straightforward. An audio amp will take a low-level music signal. This signal usually originates from a source with a fairly large impedance. It then translates this signal into a large-level signal. This large-level signal can also drive loudspeakers with small impedance. Depending on the type of amplifier, one of several kinds of elements are utilized in order to amplify the signal such as tubes and transistors.
A couple of decades ago, the most widespread type of audio amp were tube amps. Tube amps use a tube as the amplifying element. The current flow through the tube is controlled by a low-level control signal. Thereby the low-level audio is transformed into a high-level signal. Tubes, though, are nonlinear in their behavior and will introduce a quite large amount of higher harmonics or distortion. A lot of people favor tube amplifiers since those higher harmonics are often perceived as the tube amplifier sounding "warm" or "pleasant". An additional downside of tube amplifiers, however, is the low power efficiency. The majority of power which tube amplifiers consume is being dissipated as heat and merely a portion is being transformed into audio power. Moreover, tubes are pretty costly to produce. Therefore tube amplifiers have by and large been replaced by solid-state amps which I will glance at next.
In addition, tube amps have fairly low power efficiency and therefore radiate a lot of power as heat. Yet one more downside is the high price tag of tubes. This has put tube amps out of the ballpark for many consumer devices. Consequently, the majority of audio products nowadays uses solid state amplifiers. I will describe solid state amps in the following paragraphs.
The first generation types of solid state amps are generally known as "Class-A" amps. Solid-state amps employ a semiconductor as opposed to a tube to amplify the signal. Typically bipolar transistors or FETs are being utilized. In a class-A amp, the signal is being amplified by a transistor which is controlled by the low-level audio signal. Class-A amps have the smallest distortion and usually also the lowest amount of noise of any amplifier architecture. If you require ultra-low distortion then you should take a closer look at class-A types. The major drawback is that just like tube amps class A amps have extremely low efficiency. Because of this these amplifiers require large heat sinks in order to dissipate the wasted energy and are usually rather heavy.
Class-D amplifiers improve on the efficiency of class-AB amplifiers even further by utilizing a switching transistor which is always being switched on or off. Thereby this switching stage barely dissipates any energy and thereby the power efficiency of class-D amps frequently exceeds 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal has to be lowpass filtered in order to remove the switching signal and recover the music signal. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amps exhibiting bigger audio distortion than other kinds of amplifiers.
Newer amps include internal audio feedback in order to minimize the amount of audio distortion. One kind of audio amps that makes use of this type of feedback is known as "class-T" or "t amplifier". 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.
About the Author:
Click for info to help you study additional resources on the subject of class d amplifiers.
Posts
No comments:
Post a Comment