Stereo amplifiers are at the very center of every home theater system. As the quality and output power demands of today's loudspeakers increase, so do the requirements of power amplifiers. With the ever increasing quantity of models and design topologies, such as "tube amplifiers", "class-A", "class-D" as well as "t amplifier" types, it is becoming more and more demanding to select the amp which is best for a particular application. This guide is going to explain some of the most popular terms and clarify some of the technical jargon which amp manufacturers frequently employ.
A few decades ago, the most common type 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 transformed into a high-level signal. Unfortunately, tube amps have a somewhat high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. Today, tube amplifiers still have many followers. The main reason is that the distortion that tubes bring about are often perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold".
A downside of tube amps is their low power efficiency. In other words, the majority of the power consumed by the amp is wasted as heat instead of being transformed into audio. Thus tube amplifiers are going to run hot and need enough cooling. Yet another disadvantage is the big price tag of tubes. This has put tube amps out of the ballpark for a lot of consumer products. As a result, the majority of audio products nowadays utilizes solid state amps. I am going to describe solid state amps in the next sections.
Solid-state amps use a semiconductor element, like a bipolar transistor or FET rather than the tube and the first kind is often known as "class-A" amps. In class-A amps a transistor controls the current flow according to a small-level signal. Several amps utilize a feedback mechanism in order to minimize the harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest among all types of audio amplifiers. These amps also usually exhibit very low noise. As such class-A amplifiers are ideal for quite demanding applications in which low distortion and low noise are crucial. Class-A amps, though, waste most of the power as heat. Therefore they frequently have large heat sinks and are fairly heavy.
Solid-state amplifiers utilize a semiconductor element, like a bipolar transistor or FET rather than the tube and the first sort is called "class-A" amps. The working principle of class-A amps is quite similar to that of tube amps. The key difference is that a transistor is being utilized instead of the tube for amplifying the audio signal. The amplified high-level signal is sometimes fed back in order to reduce harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest amongst all types of power amps. These amps also usually exhibit very low noise. As such class-A amplifiers are perfect for very demanding applications in which low distortion and low noise are crucial. Class-A amps, though, waste the majority of the power as heat. Consequently they typically have big heat sinks and are fairly heavy.
Class-D amps are able to attain power efficiencies higher than 90% by utilizing a switching transistor that is continually being switched on and off and as a result the transistor itself does not dissipate any heat. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered to remove the switching signal and get back the music signal. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amplifiers having bigger music distortion than other kinds of amplifiers.
In order to solve the problem of high music distortion, modern switching amp styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amps (also called "t-amplifier") utilize this kind of feedback mechanism and for that reason can be manufactured very small whilst achieving small music distortion.
A few decades ago, the most common type 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 transformed into a high-level signal. Unfortunately, tube amps have a somewhat high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. Today, tube amplifiers still have many followers. The main reason is that the distortion that tubes bring about are often perceived as "warm" or "pleasant". Solid state amplifiers with low distortion, on the other hand, are perceived as "cold".
A downside of tube amps is their low power efficiency. In other words, the majority of the power consumed by the amp is wasted as heat instead of being transformed into audio. Thus tube amplifiers are going to run hot and need enough cooling. Yet another disadvantage is the big price tag of tubes. This has put tube amps out of the ballpark for a lot of consumer products. As a result, the majority of audio products nowadays utilizes solid state amps. I am going to describe solid state amps in the next sections.
Solid-state amps use a semiconductor element, like a bipolar transistor or FET rather than the tube and the first kind is often known as "class-A" amps. In class-A amps a transistor controls the current flow according to a small-level signal. Several amps utilize a feedback mechanism in order to minimize the harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest among all types of audio amplifiers. These amps also usually exhibit very low noise. As such class-A amplifiers are ideal for quite demanding applications in which low distortion and low noise are crucial. Class-A amps, though, waste most of the power as heat. Therefore they frequently have large heat sinks and are fairly heavy.
Solid-state amplifiers utilize a semiconductor element, like a bipolar transistor or FET rather than the tube and the first sort is called "class-A" amps. The working principle of class-A amps is quite similar to that of tube amps. The key difference is that a transistor is being utilized instead of the tube for amplifying the audio signal. The amplified high-level signal is sometimes fed back in order to reduce harmonic distortion. In terms of harmonic distortion, class-A amplifiers rank highest amongst all types of power amps. These amps also usually exhibit very low noise. As such class-A amplifiers are perfect for very demanding applications in which low distortion and low noise are crucial. Class-A amps, though, waste the majority of the power as heat. Consequently they typically have big heat sinks and are fairly heavy.
Class-D amps are able to attain power efficiencies higher than 90% by utilizing a switching transistor that is continually being switched on and off and as a result the transistor itself does not dissipate any heat. The switching transistor is being controlled by a pulse-width modulator. The switched large-level signal needs to be lowpass filtered to remove the switching signal and get back the music signal. Both the pulse-width modulator and the transistor have non-linearities which result in class-D amplifiers having bigger music distortion than other kinds of amplifiers.
In order to solve the problem of high music distortion, modern switching amp styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amps (also called "t-amplifier") utilize this kind of feedback mechanism and for that reason can be manufactured very small whilst achieving small music distortion.
Aucun commentaire:
Enregistrer un commentaire