Would You Rather Own A Good SET Amp, Or A Great Push Pull Amp?

Poll Time

1 - Listen to an Audio System or Audio Device added to an Audio System,  making an evaluation based on Experiences had of the Produced End Sound

pindac - Top of the List - I trust my experiences had - I trust some not all with the Math, but don't typically require any data to support what is being produced as a Sound.

I use data especially when matching speaker and amps. For instance, at first glance it would seem any flea powered SET would be fine for my 103db efficient Khorns, but upon closer examination there are two impedance dips down to around 3ohms and 43 degree  phase angles, perhaps not so good for current limited amp. But then we have differences in power supply reserves in amps, any two amps within a tube family may not be created equal.

OP

maybe i am biased but i owned SET. my audiophile friend has a great push pull amp well matched with his speakers. sounds very very good, but i still like mine (call it biased) but there is a something i hear on my gear that simply was missing on his.

So, as all people have posted above, SET has limitations. IF one is going to choose on the amplifier alone, then i would say a great Push Pull.

However, i like to point out, if your build your system  based on synergy (example, MY 845 tube amp, driving Falcon gold badge and supplemented with subwoofers) then the ball game changes. all limitations of the SET has been addressed. and the glory of the the SET is now on center stage. 

before closing, just a few days ago, a non audiophile came over, and he was interested to listen to my gear, so i did a showoff between my SS versus Tube gear, using my Falcon speakers, supplemented by subs. To him, he just wanted the sound of the 845 tube because what he hears it's involving and palpable. more than my SS. I hear it, but for me its a toss up. but for my non audiophile friend, its more than that. he is by profession a music director of a local singer/band who does shows and produces records

They subjectively have a faster attack (particularly noticeable on the reeds in oboes and clarinets and more organic reverb (best heard on good piano recordings).While @atmasphere is firmly advocating balanced connection I have so far been unable to replicate this SET advantage in a balanced setup.

@antigrunge2 If you want to hear speed in a tube amp OTLs are the king of that. 

But here’s an interesting tidbit FWIW: SETs are the slowest amps made in terms of rise time (or slew rate, whatever you want to call it). They also have the least bandwidth. 

So ’speed’ isn’t what you were hearing- its something else, and that ’else’ is distortion. If the speaker used lacked the efficiency really needed to show off an SET, the result is you will use power beyond about 20-25% of full power, at which point the onset of higher ordered harmonics will cause the amp to sound ’dynamic’. Once you understand that for what it is, the result may ruin the experience for you. If that happens, my apologies. 

If you really want to hear what PP is about, the thing to do is find a PP amp that is fully balanced and differential from input to output. The reason to do so has to do with the resulting distortion signature.

SETs have a quadratic non-linearity, which results in a prominent 2nd harmonic, which is the source of their ’magic’ and smooth sound.

An amp that has a fully balanced, differential circuit from input to output has a cubic non-linearity. This results in a dominant 3rd harmonic. If the amp is zero feedback, that third will be at slightly less amplitude than you will see in an SET of the same power at full power, IOW considerably less distortion. 

The ear treats the 2nd and 3rd in much the same way in that they are both innocuous and can mask higher ordered harmonics, while imbuing a quality audiophiles call ’warmth’.

The thing about the cubic non-linearity is succeeding harmonics fall off in amplitude at a faster rate as the order of the harmonic is decreased than seen in a circuit with a quadratic non-linearity, as distortion is compounded less from stage to stage within the amp. Its inherently lower distortion. 

Now if you mix single-ended and PP operation in the same amp (like in a Dynaco ST70) you get both non-linearities, which results in a prominent 5th harmonic (which will make the amp sound harder) thru algebraic summing. I suspect the limited set of PP amps that SET lovers tend to use to compare SETs to PP are of this type, as such designs are quite common.

When you use a limited sample size, the resulting conclusion is based on a logical fallacy- IOW its easy to fool yourself, since the results you got may have been very real but don’t describe the entirety of the pantheon. 

When you compare such an amp (which requires some digging) to an SET you find that SETs really don’t have any sonic advantage.  

@atmasphere,

As a woodwind player myself, I look for typical breathing, wind and reed rasping sounds at the very beginning of a note. Having had amps from Accuphase, Chord and a Graaf GM20 before the Wavac I can safely say that none of these as well as numerous amps in other peoples’ systems have been able to reproduce a lifelike resemblance equal to the Wavac. If you call that distortion, then be it. The amp certainly wasn’t driven too hard.

Here is the Audio Beatnik on this subject: https://www.dagogo.com/beatnik-pet-peeves-part-one/