SET the best?

In the mid-late 90’s I had a 2A3 PP amp from Cary audio. It was very SET like in its presentation and would work with not so sensitive speakers. It made several hard core SS folks listen up and take notice.  Too bad the reliability was an issue with these amps, they did sound quite good. I tried bi-amping using the2A3 on top and SS on the bottom..  Never got it sorted out well enough and moved on.. But the 2A3 sound is intoxicating.

Speaking in very broad, generalized, terms, I tend to find pushpull amps to have a "tighter" more punchy sound than SET amps.  But, too much of that quality and the sound seems a bit artificial or "mechanical" and less natural than the more relaxed sound of good SET amps.  For me, for example, KT88 pushpull amps tend to be particularly likely to sound too punchy and mechanical for my taste, but, as with everything in audio, there are always exceptions. 

I like MANY pushpull amps (this would include OTL amps), while I also like SET amps.  It is never as simple as saying one type is better than another.  Right now, I favor my pushpull 349 tube amp over my SET amp (the SET amp costs considerably more), but, in some respects I still do prefer the SET amp--although the bass is less powerful and tight, it sounds more subtly "musical" (the quality of the bass changes with the music and sounds less "same" and "mechanical" as my pushpull 349 amp).  Both sound harmonically saturated, deliver an expansive and immersive soundstage, and sound relaxed and natural while still being very lively sounding; the pushpull 349 just delivers a little bit more of these qualities.  

Speaking in very broad, generalized, terms, I tend to find pushpull amps to have a "tighter" more punchy sound than SET amps.  But, too much of that quality and the sound seems a bit artificial or "mechanical" and less natural than the more relaxed sound of good SET amps.  For me, for example, KT88 pushpull amps tend to be particularly likely to sound too punchy and mechanical for my taste, but, as with everything in audio, there are always exceptions. 

I agree- I tend to see punchy bass as a coloration, since you never seem to run into it in live events. I've played in orchestras, jazz and folk ensembles, rock bands and just not encountered it. I think its the product of an overdamped speaker to a certain degree but I don't think that's all of it.

The distortion signature is what is at play here IMO. Most pentode-based amps employ a bit of feedback, but since they really don't have enough, they have an obvious distortion signature (the amplifier's 'sonic signature'). Some of that includes harmonics of bass fundamental tones, generated by the feedback itself. The ear is interpreting them as 'punchy' (and yes, this happens with many solid state amps too). IMO/IME the way around this is to make sure the amp is as linear as possible, so much so that it will sound reasonably decent with no feedback at all. Only then do you apply the feedback- and then it should be used to control gain more than anything else. With a pentode-based amp I suspect this would mean that the output section is wired Ultra-Linear.

But many pentode output stages really aren't that linear and need the feedback to linearize them. That is a bad move IMO. You can't get rid of all the distortion and if you start with a high distortion amp, the feedback will cause it to have a less musical distortion signature overall when you're done. Amps that have zero feedback have a different distortion signature that tends to favor the lower ordered harmonics which will mask the presence of the higher orders. But if you have no feedback you also have a much more limited range of speakers that are practical with the amp. For more on this see

The Power Paradigm Vs the Voltage Paradigm

Hey Plinko, The artifacts are phase shifts. The square wave stays good, its relative position is slightly different compared to where it should be.

I'm quite amazed at the diversity of the answers and the strong conviction behind the opinions. I'm on the side of keeping an open mind, as there are always surprises and it's so easy to run into the "I stand corrected" scenario. When going for recommendations, they all come through subjective filters. Just like asking about steaks: the answer depends whether you ask a meat lover or a vegan....

When people report loving something it comes from hearing a properly set up system with that topology. Negative opinions on the other hand come from lack of experience. Do not place much value on those (regardless of what architecture is being dissed.) Just remember: audio is not a perfect science, every topology has its flaws and compromises. When the ad says that one major flaw has been corrected, it can only be done through introducing a compromise somewhere else. In most cases the manufacturers are keenly aware of the shortcomings, but they don't want to rub it in our faces. (Product will not sell.) 

All being said - solid state easier to find for show and crowd-pleasing, and SET for meditation and contemplation.

Just stay focused with your purpose: do not buy a horse to sing, and do not get a bird to pull your wagon. Enjoy diversity.

@realworldaudio  Thanks for the laugh. So which definition of Plinko should I assume? 😊

+1 to this as well as so many of your posts.