If the phrase: '100 Watts, Class A/B amp' leaves you scratching your head, you're not alone. For the beginner or newbie guitarist there are plenty of concepts that will be totally foreign when you're just starting out. One of the main ones is guitar amplifier specifications. There's many different aspects to this and for the purposes of this article, I'll be concentrating on guitar amplifier class designations. Most of this revolves around how the amp handles electrical current. You don't really have to know this to buy your first practice amp but the knowledge will make you a more well rounded musician.
Class A
In a class A amp, the current is flowing within the amp at all times, even when at idle (no music is playing). What this means is that the amp response is very fast because the current can be transferred to the speakers immediately. There is also less crossover distortion, which is a type of distortion that occurs when there is switching between devices driving a load - such as transistors. The bottom line is that Class A guitar amps sound better, respond better and as a result are more expensive to build. An example of a class A device would include the Orange AD30HTC 30 Watt Twin Channel Amp.
In a class A amp, the current is flowing within the amp at all times, even when at idle (no music is playing). What this means is that the amp response is very fast because the current can be transferred to the speakers immediately. There is also less crossover distortion, which is a type of distortion that occurs when there is switching between devices driving a load - such as transistors. The bottom line is that Class A guitar amps sound better, respond better and as a result are more expensive to build. An example of a class A device would include the Orange AD30HTC 30 Watt Twin Channel Amp.
Class B
Class B amps differ from Class A in that there is zero current flowing when the output devices are at idle. What this means is that they actually have to turn on from a state of no current when a signal becomes present. Class B designs tend to have a slower slew rate (maximum rate of change of a signal at any point in a circuit) and increased crossover distortion, but as a result are more affordable than class A.
Class B amps differ from Class A in that there is zero current flowing when the output devices are at idle. What this means is that they actually have to turn on from a state of no current when a signal becomes present. Class B designs tend to have a slower slew rate (maximum rate of change of a signal at any point in a circuit) and increased crossover distortion, but as a result are more affordable than class A.
Class AB
A combination of Class A and B, basically these amps have different parts of their output operating in either class A or B. You find the great majority of guitar amps are in this class because it is simply a more efficient way to operate. Pure Class A amps need large power supplies and tend to run hot to a large extent. This is the trade-off for the ability to instantly send a flow of current to the speakers upon receiving an input signal An example of a Class A/B guitar amp is a Mesa Boogie Dual Rectifier.
A combination of Class A and B, basically these amps have different parts of their output operating in either class A or B. You find the great majority of guitar amps are in this class because it is simply a more efficient way to operate. Pure Class A amps need large power supplies and tend to run hot to a large extent. This is the trade-off for the ability to instantly send a flow of current to the speakers upon receiving an input signal An example of a Class A/B guitar amp is a Mesa Boogie Dual Rectifier.
Class D
In this case, the output transistors are operated as switches. These amps have increased efficiency, and as a result require less robust power supplies and smaller heat sinks These are important advantages in portable and battery-powered equipment.
In this case, the output transistors are operated as switches. These amps have increased efficiency, and as a result require less robust power supplies and smaller heat sinks These are important advantages in portable and battery-powered equipment.
Class H
Class H devices are very efficient and allow for a lightweight amplifier design. There is however a drawback as distortion is more evident at lower volumes.
Class H devices are very efficient and allow for a lightweight amplifier design. There is however a drawback as distortion is more evident at lower volumes.
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