This is an area that is a little hard to explain if you do not have a little background. It deals with the amount of time that the tube (I tend to talk tubes) conducts when an input signal is applied. That is the only issue involved.
For class A, one could say that anode current is set at a level such that, even with the maximum allowable input signal, anode current never falls to zero. That is, the valve never turns off.
In class B the the anode current only flows during the positive half cycle of the input waveform.
Class AB the tube conducts more that half (180degrees) but less that all (360degrees) of the waveform.
This is less than helpful for some people. So what! you might ask, and rightfully so. If the above sounds like gibberish the best online explanation (for tubes) of it that I know of is here:
www.tpub.com/neets/book6/20j.htm
You might have to read a dozen of so pages to get enough background to make sense of it.
Above is the technical definition of class operation for an amp. There are endless debates about the advantages of each for producing music.
Cheers,
For class A, one could say that anode current is set at a level such that, even with the maximum allowable input signal, anode current never falls to zero. That is, the valve never turns off.
In class B the the anode current only flows during the positive half cycle of the input waveform.
Class AB the tube conducts more that half (180degrees) but less that all (360degrees) of the waveform.
This is less than helpful for some people. So what! you might ask, and rightfully so. If the above sounds like gibberish the best online explanation (for tubes) of it that I know of is here:
www.tpub.com/neets/book6/20j.htm
You might have to read a dozen of so pages to get enough background to make sense of it.
Above is the technical definition of class operation for an amp. There are endless debates about the advantages of each for producing music.
Cheers,