Requirements concerning audio power and audio fidelity of today's loudspeakers and home theater products are always growing. At the core of those products is the music amp. Modern stereo amps have to perform well enough to satisfy these always increasing requirements. It is difficult to select an amp given the big number of styles and concepts. I will clarify a few of the most popular amplifier designs including "tube amplifiers", "linear amplifiers", "class-AB" and "class-D" along with "class-T amps" to help you understand a few of the terms regularly utilized by amp makers. This article should also help you figure out which topology is ideal for your specific application.
The fundamental operating principle of an audio amp is fairly simple. An audio amp is going to take a low-level audio signal. This signal regularly comes from a source with a rather high impedance. It then 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 employs one or several elements which are controlled by the low-power signal in order to make a large-power signal. Those elements range from tubes, bipolar transistors to FET transistors.
Tube amps used to be popular some decades ago. A tube is able to control the current flow according to a control voltage which is connected to the tube. Unfortunately, tube amps have a fairly high level of distortion. Technically speaking, tube amplifiers are going to introduce higher harmonics into the signal. On the other hand, this characteristic of tube amps still makes these popular. A lot of people describe tube amplifiers as having a warm sound as opposed to the cold sound of solid state amplifiers.
One drawback of tube amplifiers is their low power efficiency. In other words, most of the power consumed by the amplifier is wasted as heat rather than being converted into audio. As a result tube amplifiers will run hot and need adequate cooling. Moreover, tubes are pretty expensive to build. Thus tube amps have mostly been replaced by solid-state amps which I am going to glance at next.
By using a series of transistors, class-AB amplifiers improve on the small power efficiency of class-A amps. The working region is split into 2 separate regions. These 2 areas are handled by separate transistors. Each of these transistors works more efficiently than the single transistor in a class-A amp. Because of the larger efficiency, class-AB amps do not need the same amount of heat sinks as class-A amplifiers. For that reason they can be manufactured lighter and cheaper. Class-AB amplifiers have a downside however. Every time the amplified signal transitions from one 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 amps lack audio fidelity compared with class-A amplifiers.
By employing a series of transistors, class-AB amps improve on the small power efficiency of class-A amps. The working area is split into two separate areas. These 2 regions are handled by separate transistors. Each of these transistors works more efficiently than the single transistor in a class-A amp. As such, class-AB amps are typically smaller than class-A amplifiers. When the signal transitions between the 2 separate regions, though, a certain level of distortion is being created, thus class-AB amps will not achieve the same audio fidelity as class-A amplifiers.
Class-D amplifiers improve on the efficiency of class-AB amps even further by using a switching transistor which is continuously being switched on or off. Thus this switching stage barely dissipates any energy and consequently the power efficiency of class-D amps typically surpasses 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 needs to be removed from the amplified signal by a lowpass filter. Usually a straightforward first-order lowpass is being utilized. The switching transistor and also the pulse-width modulator usually have rather big non-linearities. As a result, the amplified signal will contain some distortion. Class-D amps by nature have higher audio distortion than other kinds of audio amps. In order to resolve the dilemma of large music distortion, modern switching amplifier styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. A well-known architecture which makes use of this kind of feedback is called "class-T". Class-T amps or "t amps" attain audio distortion which compares with the audio distortion of class-A amps while at the same time offering the power efficiency of class-D amplifiers. Thus t amps can be made extremely small and still achieve high audio fidelity.
The fundamental operating principle of an audio amp is fairly simple. An audio amp is going to take a low-level audio signal. This signal regularly comes from a source with a rather high impedance. It then 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 employs one or several elements which are controlled by the low-power signal in order to make a large-power signal. Those elements range from tubes, bipolar transistors to FET transistors.
Tube amps used to be popular some decades ago. A tube is able to control the current flow according to a control voltage which is connected to the tube. Unfortunately, tube amps have a fairly high level of distortion. Technically speaking, tube amplifiers are going to introduce higher harmonics into the signal. On the other hand, this characteristic of tube amps still makes these popular. A lot of people describe tube amplifiers as having a warm sound as opposed to the cold sound of solid state amplifiers.
One drawback of tube amplifiers is their low power efficiency. In other words, most of the power consumed by the amplifier is wasted as heat rather than being converted into audio. As a result tube amplifiers will run hot and need adequate cooling. Moreover, tubes are pretty expensive to build. Thus tube amps have mostly been replaced by solid-state amps which I am going to glance at next.
By using a series of transistors, class-AB amplifiers improve on the small power efficiency of class-A amps. The working region is split into 2 separate regions. These 2 areas are handled by separate transistors. Each of these transistors works more efficiently than the single transistor in a class-A amp. Because of the larger efficiency, class-AB amps do not need the same amount of heat sinks as class-A amplifiers. For that reason they can be manufactured lighter and cheaper. Class-AB amplifiers have a downside however. Every time the amplified signal transitions from one 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 amps lack audio fidelity compared with class-A amplifiers.
By employing a series of transistors, class-AB amps improve on the small power efficiency of class-A amps. The working area is split into two separate areas. These 2 regions are handled by separate transistors. Each of these transistors works more efficiently than the single transistor in a class-A amp. As such, class-AB amps are typically smaller than class-A amplifiers. When the signal transitions between the 2 separate regions, though, a certain level of distortion is being created, thus class-AB amps will not achieve the same audio fidelity as class-A amplifiers.
Class-D amplifiers improve on the efficiency of class-AB amps even further by using a switching transistor which is continuously being switched on or off. Thus this switching stage barely dissipates any energy and consequently the power efficiency of class-D amps typically surpasses 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 needs to be removed from the amplified signal by a lowpass filter. Usually a straightforward first-order lowpass is being utilized. The switching transistor and also the pulse-width modulator usually have rather big non-linearities. As a result, the amplified signal will contain some distortion. Class-D amps by nature have higher audio distortion than other kinds of audio amps. In order to resolve the dilemma of large music distortion, modern switching amplifier styles include feedback. The amplified signal is compared with the original low-level signal and errors are corrected. A well-known architecture which makes use of this kind of feedback is called "class-T". Class-T amps or "t amps" attain audio distortion which compares with the audio distortion of class-A amps while at the same time offering the power efficiency of class-D amplifiers. Thus t amps can be made extremely small and still achieve high audio fidelity.
About the Author:
Check out this helpful resource in order to come across useful materials concerning amplifiers for speakers.
ليست هناك تعليقات:
إرسال تعليق