Craig,
if Audiogon didn't "expire" previouse and usefull archive information about classes of operation of amplifiers often appeared in discussions here than you'll find more detailed and deep explainations of classes ofoperation.
It's definitely something beyond sonic effects of one or another class of operation.
So far members explained to you differences between class A and class B but not realy class A/B.
Class A/B has a special diode placed between complementary pairs of output elements to bring the output devices from class A onto the B operation under demand of higher current or power. This actually may even be neccessary even on moderate volume levels depending on load i.e speaker. A complementary pair of transistors is defined to be opposite bias transistors(direct bias and reverse bias) with same input and output parameters. Such above described diode works as a gate between such complementary pairs and should stay "closed" when the input signal from the previous stage is less than peak and "open" once the peak input signal is reached by the previous stage transfering the output devices onto class B operation. Before the diode is "open" both groups of transistors direct and reverse bias are having their own zero-degree point of operation. After switching to class B both of output device groups transfer to one common zero degree point of operation.
Please note that previous stages in amplifier can also work as well in class A, B or AB operation.
The advantage of such A/B design is decreased distortions on higher volume levels and near-linear responce of class A on low volume levels.
Class B itself has higher distortions at low volume levels not only due to above said switching between complementary pairs but also due to some degree of parameter difference between such as well.
if Audiogon didn't "expire" previouse and usefull archive information about classes of operation of amplifiers often appeared in discussions here than you'll find more detailed and deep explainations of classes ofoperation.
It's definitely something beyond sonic effects of one or another class of operation.
So far members explained to you differences between class A and class B but not realy class A/B.
Class A/B has a special diode placed between complementary pairs of output elements to bring the output devices from class A onto the B operation under demand of higher current or power. This actually may even be neccessary even on moderate volume levels depending on load i.e speaker. A complementary pair of transistors is defined to be opposite bias transistors(direct bias and reverse bias) with same input and output parameters. Such above described diode works as a gate between such complementary pairs and should stay "closed" when the input signal from the previous stage is less than peak and "open" once the peak input signal is reached by the previous stage transfering the output devices onto class B operation. Before the diode is "open" both groups of transistors direct and reverse bias are having their own zero-degree point of operation. After switching to class B both of output device groups transfer to one common zero degree point of operation.
Please note that previous stages in amplifier can also work as well in class A, B or AB operation.
The advantage of such A/B design is decreased distortions on higher volume levels and near-linear responce of class A on low volume levels.
Class B itself has higher distortions at low volume levels not only due to above said switching between complementary pairs but also due to some degree of parameter difference between such as well.