Requirements regarding audio power and audio fidelity of today's loudspeakers and home theater systems are always growing. At the core of those products is the power amp. Today's stereo amps have to perform well enough to meet those ever increasing demands. With the ever increasing amount of models and design topologies, like "tube amplifiers", "class-A", "class-D" along with "t amplifier" types, it is becoming more and more complex to select the amplifier which is ideal for a particular application. This article is going to explain a few of the most common terms and spell out a few of the technical jargon that amplifier suppliers frequently use.
Simply put, the function of an audio amplifier is to convert a low-power music signal into a high-power audio signal. The high-power signal is great enough to drive a loudspeaker sufficiently loud. The kind of element utilized to amplify the signal depends on what amp architecture is utilized. A few amplifiers even use several kinds of elements. Usually the following parts are utilized: tubes, bipolar transistors and FETs.
Tube amps used to be common several decades ago. A tube is able to control the current flow in accordance to a control voltage that is connected to the tube. Tubes, on the other hand, are nonlinear in their behavior and are going to introduce a fairly large level of higher harmonics or distortion. Many people prefer tube amps since these higher harmonics are regularly perceived as the tube amp sounding "warm" or "pleasant".
Solid state amplifiers replace the tube with semiconductor elements, usually bipolar transistors or FETs. The first kind of solid-state amplifiers is known as class-A amps. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps utilize a feedback mechanism in order to minimize the harmonic distortion. Class-A amps have the lowest distortion and generally also the smallest amount of noise of any amplifier architecture. If you require ultra-low distortion then you should take a closer look at class-A types. Yet, similar to tube amplifiers, class-A amplifiers have very low power efficiency and the majority of the power is wasted.
To improve on the low efficiency of class-A amplifiers, class-AB amps employ a number of transistors that each amplify a separate area, each of which being more efficient than class-A amplifiers. Because of the higher efficiency, class-AB amps do not need the same number of heat sinks as class-A amplifiers. Therefore they can be made lighter and less costly. Class-AB amps have a drawback though. Every time the amplified signal transitions from a region to the other, there will be certain distortion generated. In other words the transition between these 2 regions is non-linear in nature. Therefore class-AB amplifiers lack audio fidelity compared with class-A amps.
To improve on the low efficiency of class-A amplifiers, class-AB amps make use of a series of transistors that each amplify a distinct area, each of which being more efficient than class-A amps. The larger efficiency of class-AB amplifiers also has two further advantages. Firstly, the necessary amount of heat sinking is minimized. For that reason class-AB amplifiers can be made lighter and smaller. For that reason, class-AB amps can be manufactured cheaper than class-A amplifiers. Though, this architecture adds some non-linearity or distortion in the region where the signal switches between those areas. As such class-AB amps usually have higher distortion than class-A amps.
In order to resolve the problem of large audio distortion, modern switching amplifier styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amplifiers (also called "t-amplifier") use this type of feedback mechanism and thus can be made very small whilst attaining small audio distortion.
Simply put, the function of an audio amplifier is to convert a low-power music signal into a high-power audio signal. The high-power signal is great enough to drive a loudspeaker sufficiently loud. The kind of element utilized to amplify the signal depends on what amp architecture is utilized. A few amplifiers even use several kinds of elements. Usually the following parts are utilized: tubes, bipolar transistors and FETs.
Tube amps used to be common several decades ago. A tube is able to control the current flow in accordance to a control voltage that is connected to the tube. Tubes, on the other hand, are nonlinear in their behavior and are going to introduce a fairly large level of higher harmonics or distortion. Many people prefer tube amps since these higher harmonics are regularly perceived as the tube amp sounding "warm" or "pleasant".
Solid state amplifiers replace the tube with semiconductor elements, usually bipolar transistors or FETs. The first kind of solid-state amplifiers is known as class-A amps. In class-A amps a transistor controls the current flow according to a small-level signal. Some amps utilize a feedback mechanism in order to minimize the harmonic distortion. Class-A amps have the lowest distortion and generally also the smallest amount of noise of any amplifier architecture. If you require ultra-low distortion then you should take a closer look at class-A types. Yet, similar to tube amplifiers, class-A amplifiers have very low power efficiency and the majority of the power is wasted.
To improve on the low efficiency of class-A amplifiers, class-AB amps employ a number of transistors that each amplify a separate area, each of which being more efficient than class-A amplifiers. Because of the higher efficiency, class-AB amps do not need the same number of heat sinks as class-A amplifiers. Therefore they can be made lighter and less costly. Class-AB amps have a drawback though. Every time the amplified signal transitions from a region to the other, there will be certain distortion generated. In other words the transition between these 2 regions is non-linear in nature. Therefore class-AB amplifiers lack audio fidelity compared with class-A amps.
To improve on the low efficiency of class-A amplifiers, class-AB amps make use of a series of transistors that each amplify a distinct area, each of which being more efficient than class-A amps. The larger efficiency of class-AB amplifiers also has two further advantages. Firstly, the necessary amount of heat sinking is minimized. For that reason class-AB amplifiers can be made lighter and smaller. For that reason, class-AB amps can be manufactured cheaper than class-A amplifiers. Though, this architecture adds some non-linearity or distortion in the region where the signal switches between those areas. As such class-AB amps usually have higher distortion than class-A amps.
In order to resolve the problem of large audio distortion, modern switching amplifier styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amplifiers (also called "t-amplifier") use this type of feedback mechanism and thus can be made very small whilst attaining small audio distortion.
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