Class A, AB

I saw some amps that are Class A, Class AB. Do these amps switch to AB at a certain power level? Where do they usually change to AB?

neilmc06-02-2008 9:16pm

rodman99999 Details Discussions Posts This discussion Message User 5,984 posts 06-02-2008 at 11:07pm Copy Comment URL Report Comment Edit Delete Most amplifiers are called "Class A/B" because the operate in Class A at very low power outputs, then switch to Class B operation at higher outputs. A 100 watt amp may put out 5 watts in Class A, then switch to Class B above that level. Even the most powerful A/B amps can only output about 15% of rated power in Class A. Typically, it's more like 5%.
rodman99999 Details Discussions Posts This discussion Message User 5,984 posts 06-02-2008 at 11:11pm Copy Comment URL Report Comment Edit Delete OOPS- I should have said, "Most Solid State amplifiers".
atmasphere Details Discussions Posts This discussion Message User 11,577 posts 06-03-2008 at 03:32am Copy Comment URL Report Comment Edit Delete Neilmc , if the amp is AB it will be class A (does not go into cutoff) to a certain point and above a certain power the amplifier will operate in the 'B' region, IOW part of the amp goes into cutoff as the waveform amplitude increases. There is no such thing as combining Class A with Class AB- such an amplifier is by definition Class AB only. Class A means that at no time during the amplification of the signal does the amplifier or a portion of the amplifier go into cutoff, such that only a part of the circuit is handling the signal. All single-ended amps are Class A BTW.