Amplifiers class A vs AB?

[arebalos]

I posted the initial question trying to understand the differences in design (and sound) between my old Krell FPB300 (with me for more than five years) and my new mc602.
To me the 602 sounds much better than the FPB300. Being the 300 a class A amp which according to Krell doubles its power every time the impedance halves, according to strictly common knowledge it SHOULD sound batter than the Mc...But to me the Mc sounds much BETTER. After reading all the responses and mainly Ron-c's it seems, in the end, that class is just a factor to take into consideration. Perhaps a Mcintosh AB or B class amplifier sounds better than a Krell class A amp, but the Krell sounds better than, say a Parasound...The answer is in the ear of the beholder.

 

[Photobitstream]

...The answer is in the ear of the beholder.

Or the ear of the behearer*.

*Dewey Redman

 

[OvenMaster]

Yes, but it is very subtle and will not be revealed with headphones, because they are a very light load for the amp.

As for which is best, A, AB or B - this is like asking wether a stickshift or an automatic is best. It all depends on the application. All other things being equal, it becomes an exercise of balancing relatively small performance differences with large differences in practicality. Class A is best, but is it worth producing 7W of heat for every 1W of output power (which comes at a hefty cost) to get half of an already very low distortion figure? Arguably, not a problem for 10W of output power, but at 100W the priorities are different...

Well said, and thanx, Ilimzn! Yes, I tried the Yamaha with my speakers at different volumes, in Class A and "Normal" operation. I still can't tell the difference! Since summer's coming and the listening room isn't air-conditioned I think I'll keep it on "Normal". In this case, practicality wins.
Tom

 

[henry.bowman]

Well said, and thanx, Ilimzn! Yes, I tried the Yamaha with my speakers at different volumes, in Class A and "Normal" operation. I still can't tell the difference! Since summer's coming and the listening room isn't air-conditioned I think I'll keep it on "Normal". In this case, practicality wins.
Tom

Tom:

I owned a Plinius SA-102 for a while, and there was quite a difference between A and A/B mode, but it doesn't rear itself immediately.

I found that after switching to class A things change after the thing heats up, which takes about 20 minutes. It's easier to tell differences going the other way. It's not stark, but things are more pretty and seem more "lit from within" in class A.

I must ask a question of arebalos. Do you find the 602 to be as articulate as the FPB? I am curious because that is another piece I am looking at for a perspective amp purchase. I find the highs to be very articulate and holographic on the FPB. I can't tell on the MC402 b/c it's paired with different gear.

Thanks,

Henry

 

[arebalos]

Hello
Well yes, perhaps the Krell appears to be more detailed, but what I found is that after, say, two hours of listening at high volume (besides the amp being VERY HOT) I needed a rest. That does not happens to me with the MC602. Just for the record, my FPB worked with a Krell Showcase pre amp and the 602 with an MX135, so perhaps the compairson is not totally scientific. :scratch2:

 

[OvenMaster]

Tom:

I owned a Plinius SA-102 for a while, and there was quite a difference between A and A/B mode, but it doesn't rear itself immediately.

I found that after switching to class A things change after the thing heats up, which takes about 20 minutes. It's easier to tell differences going the other way. It's not stark, but things are more pretty and seem more "lit from within" in class A.

Thanks,

Henry

Hm. Okay. I guess I'll have to try again and really try to pay attention. If I still don't notice any difference then perhaps it's my ears (which aren't the greatest anyhow) or perhaps my speakers don't offer enough resolution or detail. I love 'em, but no, they're not in the same league as speakers that cost mucho dinero. Thanx, Henry.

Tom

P.S. Feels kinda weird posting this in a Mac forum. You sure I'm welcome here? :lmao: