Expensive Tube Amplifiers

It was explained to me that there isn’t the usual distortion that push pull tube amps have because of the single output tube. Apparently with push pull there is distortion when one tube hands off to the other tube.

@vuch This statement is false and is a common myth. A push-pull amp can sound better than any SET by any metric an audiophile might find important. It depends on the topology of the amp and its execution. The reason has to do with how the various topologies made distortion, which is the main thing we hear as differences between amps (in much the same way we can hear differences between a cheap violin and a Stradivarius, since harmonics are how our ears assign tonality). 

If you mix push pull and single-ended circuits in the same amp you can get a prominent 5th harmonic, which is why SET lovers reject such amps. But that can be avoided by simply making the amp entirely differential from input to output, thus avoiding that pesky 5th harmonic issue. At that point the amp will be considerably lower distortion even without feedback and the higher ordered harmonics that make amps sound unpleasant will be seen to fall off at a faster rate as the order of the harmonic is increased. This allows the amp to sound smoother. 

@atmasphere As I mentioned above, I've had a push pull SET in the NAT Audio Generator and a SET single tube in the Magma M, both with comparable power ratings. The rest of the gear and, room layout was exactly the same. I'm not an expert but I'd imagine the differences in sonic quality has more to do with just differences in tube topography but that is probably a big reason for the sonic differences. The sonic improvements with Magma M's over the Generators was easily noticeable. I've enjoyed many push pull amplifiers but after hearing the Magma M's I won't be changing power amplification in my reference rig ever again. 

Regarding other tube amplification design, I am excited to see what a reconditioned Sansui 1000a receiver will do in my vintage rig. I've heard that model tube receiver was the gold standard of tube receivers for Sansui.

My tech said the reconditioned Harman Kardon 930 Twin Powered receiver he just completed for my vintage rig will be blown out of the water by the Sansui when it's finished.

Could this hobby get any more fun? I don't think so.

 

As I mentioned above, I’ve had a push pull SET in the NAT Audio Generator and a SET single tube in the Magma M, both with comparable power ratings.

@vuch ’SET’ stands for Single-Ended Triode. So there’s no such thing as a ’push-pull SET’ as you mentioned above. What did you mean by that?

@atmasphere I was mistaken. The Generators weren’t SET, they were push pull. My bad...

This is more accurate of what the Generators were: 

NAT Audio Generator mono block amplifiers use a pure single-ended, triode-based configuration in pure class A, employing zero global feedback. These amplifiers often feature military-grade single coaxial triode ceramic output tubes, such as the GI-7B for the Generator models, in a triode-based circuit. 

@vuch OK that's actually an SET. A really high powered one, hence the cabinet so to keep the user away from the really high Voltages needed for the ceramic transmitting triode it uses. Not push pull.