None of latest stereo products would be doable lacking the aid of today's audio amplifiers that try to satisfy higher and higher requirements regarding power and music fidelity. There is a large amount of amplifier styles and types. All of these differ regarding performance. I will describe a few of the most popular amp 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 guide you should be able to comprehend the amplifier specs which suppliers publish.
Simply put, the principle of an audio amplifier is to translate a low-power music signal into a high-power audio signal. The high-power signal is large enough to drive a loudspeaker sufficiently loud. Determined by the type of amp, one of several types of elements are utilized in order to amplify the signal like tubes as well as transistors.
A couple of decades ago, the most popular kind of audio amplifier were tube amplifiers. 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 converted into a high-level signal. Tubes, though, are nonlinear in their behavior and will introduce a fairly large amount of higher harmonics or distortion. Today, tube amps still have a lot of fans. The most important reason is that the distortion that tubes bring about are frequently perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold". In addition, tube amplifiers have quite small power efficiency and therefore dissipate a lot of power as heat. Yet an additional disadvantage is the high price tag of tubes. This has put tube amps out of the ballpark for many consumer devices. Because of this, the majority of audio products nowadays utilizes solid state amps. I will describe solid state amps in the following paragraphs.
Also, tube amps have fairly small power efficiency and thus radiate much power as heat. Also, tubes are quite expensive to manufacture. Therefore tube amplifiers have mostly been replaced by solid-state amplifiers which I will look at next.
Solid state amplifiers replace the tube with semiconductor elements, generally bipolar transistors or FETs. The earliest type of solid-state amps is known as class-A amplifiers. In class-A amps a transistor controls the current flow according to a small-level signal. A few amps utilize a feedback mechanism in order to reduce the harmonic distortion. Class-A amps have the lowest distortion and typically 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 models. Class-A amplifiers, on the other hand, waste the majority of the energy as heat. For that reason they typically have big heat sinks and are fairly bulky.
Class-AB amps improve on the efficiency of class-A amps. They use a series of transistors to break up the large-level signals into two separate regions, each of which can be amplified more efficiently. The higher efficiency of class-AB amplifiers also has 2 further benefits. Firstly, the required number of heat sinking is reduced. Therefore class-AB amps can be manufactured lighter and smaller. For that reason, class-AB amps can be made cheaper than class-A amps. When the signal transitions between the two separate regions, though, some level of distortion is being created, thus class-AB amplifiers will not achieve the same audio fidelity as class-A amps.
In order to further improve the audio efficiency, "class-D" amplifiers utilize a switching stage which is continuously switched between two states: on or off. None of these 2 states dissipates power inside the transistor. Consequently, class-D amplifiers regularly are able to attain power efficiencies beyond 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered in order to remove the switching signal and recover the audio signal. 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 amplifier. In order to resolve the dilemma of high music distortion, modern switching amplifier designs include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amplifiers (also referred to as "t-amp") employ this sort of feedback method and thus can be manufactured extremely small whilst attaining small audio distortion.
Simply put, the principle of an audio amplifier is to translate a low-power music signal into a high-power audio signal. The high-power signal is large enough to drive a loudspeaker sufficiently loud. Determined by the type of amp, one of several types of elements are utilized in order to amplify the signal like tubes as well as transistors.
A couple of decades ago, the most popular kind of audio amplifier were tube amplifiers. 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 converted into a high-level signal. Tubes, though, are nonlinear in their behavior and will introduce a fairly large amount of higher harmonics or distortion. Today, tube amps still have a lot of fans. The most important reason is that the distortion that tubes bring about are frequently perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold". In addition, tube amplifiers have quite small power efficiency and therefore dissipate a lot of power as heat. Yet an additional disadvantage is the high price tag of tubes. This has put tube amps out of the ballpark for many consumer devices. Because of this, the majority of audio products nowadays utilizes solid state amps. I will describe solid state amps in the following paragraphs.
Also, tube amps have fairly small power efficiency and thus radiate much power as heat. Also, tubes are quite expensive to manufacture. Therefore tube amplifiers have mostly been replaced by solid-state amplifiers which I will look at next.
Solid state amplifiers replace the tube with semiconductor elements, generally bipolar transistors or FETs. The earliest type of solid-state amps is known as class-A amplifiers. In class-A amps a transistor controls the current flow according to a small-level signal. A few amps utilize a feedback mechanism in order to reduce the harmonic distortion. Class-A amps have the lowest distortion and typically 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 models. Class-A amplifiers, on the other hand, waste the majority of the energy as heat. For that reason they typically have big heat sinks and are fairly bulky.
Class-AB amps improve on the efficiency of class-A amps. They use a series of transistors to break up the large-level signals into two separate regions, each of which can be amplified more efficiently. The higher efficiency of class-AB amplifiers also has 2 further benefits. Firstly, the required number of heat sinking is reduced. Therefore class-AB amps can be manufactured lighter and smaller. For that reason, class-AB amps can be made cheaper than class-A amps. When the signal transitions between the two separate regions, though, some level of distortion is being created, thus class-AB amplifiers will not achieve the same audio fidelity as class-A amps.
In order to further improve the audio efficiency, "class-D" amplifiers utilize a switching stage which is continuously switched between two states: on or off. None of these 2 states dissipates power inside the transistor. Consequently, class-D amplifiers regularly are able to attain power efficiencies beyond 90%. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered in order to remove the switching signal and recover the audio signal. 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 amplifier. In order to resolve the dilemma of high music distortion, modern switching amplifier designs include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amplifiers (also referred to as "t-amp") employ this sort of feedback method and thus can be manufactured extremely small whilst attaining small audio distortion.
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