Class A/B switching cause sonic problems?


I have heard different thoughts on this subject and was looking for some other opinions.
Spoke with Mike Creek at HE 2002 and he did not feel there was any degradation when you have a power amp that switches between Class A ( for the 1st watt) and Class B (for power over 1 watt). He though class A's inefficiency and heat generated were not worth whatever benefits there may be. Maybe modern A/B designs don't have problems like older designs did.
Then I saw an article somewhere on the web (darned if I can find it now) where another power amp designer was strongly against switching power supplies.
Is there any agreement on this subject as to who is right?
cdc
From experience I agree with Mike Creek in that an amp that has class A drivers with class AB outputs is certainly a legitimate design topology. I've used more than one solid state amp product that works this way & they sound just fine to me, and I am quite particular about sound quality. Of course a pure class A design is going to have a more purified sound than the hybrid design, but the tradeoff is a lot of wasted electricity & a hotter listening room. This extra heat isn't really an issue during cooler seasons, but on warmer days you'll certainly notice higher AC bills &/or a hotter house. Simply let your ears decide which you most prefer.
The amp doesn't normally "switch" back & forth though, this is simply driven by the input signal level exciting whichever stages at any given moment in time. One exception is the old Carver commutating power supply, but I wouldn't recommend that deisgn for any critical-quality applications.
Switching power supplies might be found in either type of design, & yes they can be noisy (although more efficient). In a properly designed component, either linear or switching power supply could sound equally good. I believe that Meitner, Rowland, & more recently TACT have manufactured examples of properly designed & executed "switchers".
Hi Bob. I guess I'm not totally clear on A/B amps. So you're saying the amp will switch even even I kept volume levels low so not to go above 1 watt output on the power amp? Aren't these amps supposed to put out class "A" for the first watt? Then "B" after that?
There don't seem to be any class "A" amps available anymore that I know of so maybe the market has decided for me what I want. But I do know ATC does use class "A" amps in their active speakers.
Thanks evryone for the help.
I can answer it as well.
1 watt of output power is measured according to a certain freequency probably 1000Hz. If it goes to the bass freequencies it would anyway switch since higher current is drown onto the load greatly increasing a slew ratio...
There are A/B amps where the switch to B occurs arround 25...30W where you normally listen to them in class A.