Why would anyone want class AB amp when class A always sounds better ?

So, with less than capable speakers and headphones class AB can sound better ?

It can sound better even with great speakers! The sound of any amplifier is always about what distortion it makes, and what distortion it doesn't. You can prevent crossover distortion in any AB circuit, since its a function of push-pull rather than whether its class A or not. The only exception is if the amp is operating class B but I don't know of a single example of a class B amp in high end audio.

The sound of any amplifier is always about what distortion it makes

The sound of ANY amplifier is better without ANY distortions whatsoever. (Sure some distortions are not AS bad as others.)
So long as very little distortion is NOT attained by using means that create other problems areas EG: like masses of feedback global or local, global especially!
And there no such thing as "good" sounding class-B xover distortion!

The sound of ANY amplifier is better without ANY distortions whatsoever. (Sure some distortions are not AS bad as others.)
So long as very little distortion is NOT attained by using means that create other problems areas EG: like masses of feedback global or local, global especially!

Of course, this being planet Earth, there are no amplifiers with no distortion.


Feedback is problematic in insufficient amounts- it can cause brightness and harshness as it introduces distortions of its own (mostly higher ordered harmonics). But if you are able to apply enough feedback then this phenomena does not occur. That amount seems to be north of 35dB. This also has to be consistent at all frequencies. Most amps have sufficient feedback at 100Hz (which is why they are usually measured at only 100Hz and not higher), but at 1KHz and 10KHz is where amps get into trouble. As a result most of the amps using feedback made in the last 60 years have increasing distortion as frequency goes up, because the amount of feedback is falling off, due to insufficient Gain Bandwidth Product.


This is why solid state in particular has gotten a reputation for being bright and harsh (and it does not matter what class of operation is being used) because the ear is very sensitive to those harmonics! This is literally why tube amps are still around since they can mask the higher ordered harmonics they make.

Like I said, once again.

"There no such thing as a "good sounding" class-B xover distortion!"
Because Class-B xover distortion it’s NOT a "nice/colored" sounding distortion like many tubes give, and to eliminate if possible (without sterilizing the sound it with large amounts of feedback) is ALWAYS better than having it.

And those that continue to profess that a Class-B amps xover distortion can sound as good if not better than no xover distortion in Class-A amp are seriously kidding themselves, and worse are charlatans.

Cheers George

Hmm, I don’t get it. When I owned a Plinius SA100 mkiii amp the difference from class A listening to A/B was like night and day. The amp of course does both Class A and Class A/B. It’s as if the lights were turned on. I’ve owned lots of Class A from Threshold T400, T200, Coda, Pass Labs, Plinius, and it wasn’t until I switched to tubes did I begin to here something different.


But SS Class A is as good as it gets to my ears. To those that can’t hear a difference I feel a bit sorry for you for you don’t know what you’re missing. Class A is where it’s at. Whomever suggested Class D was better than Class A suggests they’re in Audio training and haven’t had their training wheels removed.