OK, here's an explanation for your non-audiophile friends & for you:
class-A amplifiers are a class of power amplifiers where the output transistors (or output stage) driving the loud speakers are always on & are always dissipating the maximum wattage that the power amplifier is rated for. Due to this fact, the heat sinks of class-A power amplifiers get very hot - 54C is considered the norm. Class-A power amplifiers actually run a bit cooler when the music is playing because a significant portion of the output wattage is delivered to the loudspeaker (rather than being dissipated as heat when no music is playing). The advantage of class-A power amplifiers is that, since the output stage is always on at full power, there is minimal amount of signal distortion (THD).
in a class-AB power amplifier, the output stage driving the louspeaker is biased at a very low level in comparison to a class-A power amp such that the output stage is considered to be weakly on (as compared to being full-power on in class-A and completely off in a class-B power amp). The reason for having the output stage weakly on is to avoid what is called as "cross-over distortion". Cross-over distortion occurs when the power amp needs to follow a music signal that is going from a positive cycle to a negative cycle or vice-versa and some time is required for the transistors servicing the negative cycle to turn on (pos cycle --> neg cycle). The advantage of a class-AB power amp is that it consumes much less power during idle & remains warm to the touch (as opposed to hot/scalding to the touch for a class-A power amp). The cross-over distortion is minimized in a class-AB power amp but I believe that it is not eliminated.
There are several well-known amp designers who subscribe to the view that a class-AB power amp can sound just as rewarding as a class-A power amp & that it is all in the implementation.
Hope that this helps.....
class-A amplifiers are a class of power amplifiers where the output transistors (or output stage) driving the loud speakers are always on & are always dissipating the maximum wattage that the power amplifier is rated for. Due to this fact, the heat sinks of class-A power amplifiers get very hot - 54C is considered the norm. Class-A power amplifiers actually run a bit cooler when the music is playing because a significant portion of the output wattage is delivered to the loudspeaker (rather than being dissipated as heat when no music is playing). The advantage of class-A power amplifiers is that, since the output stage is always on at full power, there is minimal amount of signal distortion (THD).
in a class-AB power amplifier, the output stage driving the louspeaker is biased at a very low level in comparison to a class-A power amp such that the output stage is considered to be weakly on (as compared to being full-power on in class-A and completely off in a class-B power amp). The reason for having the output stage weakly on is to avoid what is called as "cross-over distortion". Cross-over distortion occurs when the power amp needs to follow a music signal that is going from a positive cycle to a negative cycle or vice-versa and some time is required for the transistors servicing the negative cycle to turn on (pos cycle --> neg cycle). The advantage of a class-AB power amp is that it consumes much less power during idle & remains warm to the touch (as opposed to hot/scalding to the touch for a class-A power amp). The cross-over distortion is minimized in a class-AB power amp but I believe that it is not eliminated.
There are several well-known amp designers who subscribe to the view that a class-AB power amp can sound just as rewarding as a class-A power amp & that it is all in the implementation.
Hope that this helps.....