Compared to Class A amplifier
the Class B amplifiers do not have the dc bias current and therefore consume
considerably less power. The output transistors in Class B topology are controlled
individually. That is when the high MOSFET is on it supplies positive current to the
speaker and when the low MOSFET is on it tries to sink negative currents. This is why
Class B amplifiers dissipate less power but in trade off with power we get mediocre
sound quality. Theoretically the maximum efficiency for a Class B amplifier is about
78.5%.
Figure 2: