Music amplifiers are at the very center of each home theater product. As the quality and output power requirements of modern speakers increase, so do the requirements of music amps. With the ever increasing amount of models and design topologies, such as "tube amps", "class-A", "class-D" in addition to "t amplifier" types, it is getting more and more demanding to select the amp that is ideal for a specific application. This post will describe some of the most widespread terms and clarify some of the technical jargon that amplifier producers often employ.
An audio amp will convert a low-level music signal which frequently comes from a high-impedance source into a high-level signal which may drive a speaker with a low impedance. In order to do that, an amp uses one or several elements which are controlled by the low-power signal to create a large-power signal. Those elements range from tubes, bipolar transistors to FET transistors.
A few decades ago, the most common kind of audio amp were tube amps. Tube amps make use of 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. Sadly, tube amps have a reasonably high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. However, this characteristic of tube amps still makes these popular. A lot of people describe tube amps as having a warm sound as opposed to the cold sound of solid state amplifiers. Besides, tube amplifiers have fairly small power efficiency and consequently dissipate a lot of power as heat. In addition, tubes are rather costly to build. As a result tube amps have mostly been replaced by solid-state amplifiers which I will look at next.
Also, tube amplifiers have quite small power efficiency and thus radiate much power as heat. In addition, tubes are rather costly to make. Consequently tube amplifiers have generally been replaced by solid-state amps which I am going to glance at next.
Class-AB amplifiers improve on the efficiency of class-A amplifiers. They make use of a series of transistors to split up the large-level signals into two distinct areas, each of which can be amplified more efficiently. The larger efficiency of class-AB amplifiers also has two other benefits. First of all, the required number of heat sinking is minimized. For that reason class-AB amps can be manufactured lighter and smaller. For that reason, class-AB amps can be made cheaper than class-A amplifiers. When the signal transitions between the 2 distinct areas, however, some level of distortion is being generated, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amps.
Class-D amplifiers are able to attain power efficiencies above 90% by utilizing a switching transistor which is continuously being switched on and off and thus the transistor itself does not dissipate any heat. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component that needs to be removed from the amplified signal by using a lowpass filter. The switching transistor and also the pulse-width modulator typically exhibit quite large non-linearities. As a result, the amplified signal will contain some distortion. Class-D amps by nature exhibit higher audio distortion than other types of audio amplifiers.
In order to further improve the audio efficiency, "class-D" amplifiers make use of a switching stage that is continually switched between 2 states: on or off. None of these two states dissipates power within the transistor. Therefore, class-D amplifiers frequently are able to achieve power efficiencies higher than 90%. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Standard 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. Typically a simple first-order lowpass is being utilized. The switching transistor and in addition the pulse-width modulator generally have rather big non-linearities. As a result, the amplified signal is going to have some distortion. Class-D amplifiers by nature exhibit larger audio distortion than other types of audio amps. To solve the dilemma of high audio distortion, modern switching amplifier designs incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amplifiers (also called "t-amp") employ this sort of feedback method and thus can be manufactured extremely small while attaining low music distortion.
An audio amp will convert a low-level music signal which frequently comes from a high-impedance source into a high-level signal which may drive a speaker with a low impedance. In order to do that, an amp uses one or several elements which are controlled by the low-power signal to create a large-power signal. Those elements range from tubes, bipolar transistors to FET transistors.
A few decades ago, the most common kind of audio amp were tube amps. Tube amps make use of 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. Sadly, tube amps have a reasonably high amount of distortion. Technically speaking, tube amplifiers will introduce higher harmonics into the signal. However, this characteristic of tube amps still makes these popular. A lot of people describe tube amps as having a warm sound as opposed to the cold sound of solid state amplifiers. Besides, tube amplifiers have fairly small power efficiency and consequently dissipate a lot of power as heat. In addition, tubes are rather costly to build. As a result tube amps have mostly been replaced by solid-state amplifiers which I will look at next.
Also, tube amplifiers have quite small power efficiency and thus radiate much power as heat. In addition, tubes are rather costly to make. Consequently tube amplifiers have generally been replaced by solid-state amps which I am going to glance at next.
Class-AB amplifiers improve on the efficiency of class-A amplifiers. They make use of a series of transistors to split up the large-level signals into two distinct areas, each of which can be amplified more efficiently. The larger efficiency of class-AB amplifiers also has two other benefits. First of all, the required number of heat sinking is minimized. For that reason class-AB amps can be manufactured lighter and smaller. For that reason, class-AB amps can be made cheaper than class-A amplifiers. When the signal transitions between the 2 distinct areas, however, some level of distortion is being generated, thereby class-AB amplifiers will not achieve the same audio fidelity as class-A amps.
Class-D amplifiers are able to attain power efficiencies above 90% by utilizing a switching transistor which is continuously being switched on and off and thus the transistor itself does not dissipate any heat. The switching transistor, that is being controlled by a pulse-width modulator generates a high-frequency switching component that needs to be removed from the amplified signal by using a lowpass filter. The switching transistor and also the pulse-width modulator typically exhibit quite large non-linearities. As a result, the amplified signal will contain some distortion. Class-D amps by nature exhibit higher audio distortion than other types of audio amplifiers.
In order to further improve the audio efficiency, "class-D" amplifiers make use of a switching stage that is continually switched between 2 states: on or off. None of these two states dissipates power within the transistor. Therefore, class-D amplifiers frequently are able to achieve power efficiencies higher than 90%. The on-off switching times of the transistor are being controlled by a pulse-with modulator (PWM). Standard 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. Typically a simple first-order lowpass is being utilized. The switching transistor and in addition the pulse-width modulator generally have rather big non-linearities. As a result, the amplified signal is going to have some distortion. Class-D amplifiers by nature exhibit larger audio distortion than other types of audio amps. To solve the dilemma of high audio distortion, modern switching amplifier designs incorporate feedback. The amplified signal is compared with the original low-level signal and errors are corrected. "Class-T" amplifiers (also called "t-amp") employ this sort of feedback method and thus can be manufactured extremely small while attaining low music distortion.
No comments:
Post a Comment