SET vs Push-Pull Tube Amps?

[Olson_jr]

SET vs Push-Pull Tube Amps?​

So why do certain sounds seem to pop out of mid-air when listening to SETs but seem to be buried in the mix when listening to push-pull amps?

I frequently get this “I could reach out and touch this singer or guitar or.." on SET amps and I do not get that on PP amps.

To me, it makes the music much more interesting, especially when critically listening.

 

[mhardy6647]

I don't know.
It's either the very different spectrum of harmonic distortion products in a single-ended vs. push-pull amp.
or
It's the complete lack of crossover distortion.
or
It's magic.

I'd say they're all equally likely explanations.
🧐

 

[Olson_jr]

I don't know.
It's either the very different spectrum of harmonic distortion products in a single-ended vs. push-pull amp.
or
It's the complete lack of crossover distortion.
or
It's magic.

I'd say they're all equally likely explanations.
🧐

Well, if it is some form of harmonic distortion, it sure makes drums sound more real to me.

 

[mhardy6647]

There's a flesh-and-blood real-ness that is pretty irresistible (at least to me).
The SE 2A3 almost never fail to get the job done for me, after ca. 2 decades with SE amps*. Only with some lackluster recordings is my reaction "meh."

I do suspect that good linearity at really low output power is part of it, too -- with appropriately sensitive loudspeakers, of course. 🧐

________________
* I just did a little mental math (cf. the "Listener" auction thread for some idea of how accurate that might be...) -- counting the Decware Zen SE-84B, probably 24 years predominantly single-ended, to date.

 

[Wntrmute2]

I suspect that it may be one of two things.
One is that the signal isn't split apart and then knitted back together so there are multiple points where badness could occur. Along the same lines, the tubes in each channel need to perform perfectly with respect to each other or "smearing" occurs.
Two, and I suspect most importantly, the kind of speakers that work best with SET amplifiers lend themselves to the kind of presentation you prefer.
Or, it could be the psychedelics you took in your youth.

 

[adaug]

I suspect most importantly, the kind of speakers that work best with SET amplifiers lend themselves to the kind of presentation you prefer.

brilliant observation here. it seems to make sense that more efficient/sensitive speakers will do a better job conveying low-level details.

 

[MikeyFresh]

Or, it could be the psychedelics you took in your youth.

Brilliant observation there, this can't be fully overlooked.

It's magic.

That it is, and I remember the first time I ever heard it, a local dealer was demonstrating the then new Cary CAD-300B mono blocks and Reference 3A Royal Master around 1994 or so. Captivating to say the least.

 

[MrEd]

I think it's amplifier design.
A well designed pp amp can surprise you.
Most se amp are for the most part dht due the hype, yet few own dht pp amps.
I would welcome anyone to audition my 2a3 pp amps and their choice of se amp.
Ok .. I'm ducking my head for the bullets to fly 🙄

 

[paul_b]

Most push-pull amps are optimized for high power output and require lots of global feedback to operate properly. It's pretty much impossible to put that much global feedback around a SET amp without making it very conditionally stable, so you end up with a lot of zero feedback SET amps and nearly no zero feedback PP amps.

 

[Billet]

I suspect that it may be one of two things.
One is that the signal isn't split apart and then knitted back together so there are multiple points where badness could occur. Along the same lines, the tubes in each channel need to perform perfectly with respect to each other or "smearing" occurs.

Nicely worded... I don't like like the idea of splitting the signal into 2 phases either. It just seems wrong!

 

[MrEd]

Most push-pull amps are optimized for high power output and require lots of global feedback to operate properly. It's pretty much impossible to put that much global feedback around a SET amp without making it very conditionally stable, so you end up with a lot of zero feedback SET amps and nearly no zero feedback PP amps.

Agree

 

[Punker X]

One is that the signal isn't split apart and then knitted back together so there are multiple points where badness could occur. Along the same lines, the tubes in each channel need to perform perfectly with respect to each other or "smearing" occurs.

One issue with this theory. The OP listens to a digital stream that has been torn apart and stitched back together innumerable times. On the bench a properly designed and biased push pull amp will have less distortion than a most single ended amps. Yet I still seem to prefer singled ended amps. I chalk it up to magic.

 

[MrEd]

A dht PP amp with interstage transformer for phase splitting and no feedback is my recipe.
To me it's the best of both with the midrange sweetness, great dynamics, and plenty of balls in the bass

 

[Wntrmute2]

A dht PP amp with interstage transformer for phase splitting and no feedback is my recipe.
To me it's the best of both with the midrange sweetness, great dynamics, and plenty of balls in the bass

Is there a schematic somewhere?

 

[MrEd]

Is there a schematic somewhere?

I have build thread here.
Not sure I ever posted the schematic.
I will try to post later today.

 

[RPMac]

I don't know.
It's either the very different spectrum of harmonic distortion products in a single-ended vs. push-pull amp.
or
It's the complete lack of crossover distortion.
or
It's magic.

I'd say they're all equally likely explanations.
🧐

I’m going with “magic“
The magic is in the DHTs
More DHTs, more magic
All DHTs the best

And, of course, must have the right speakers

 

[Opa1]

The signal, Push Pull doesn't know where to go, the other is SET in it's ways. LOL

 

[RPMac]

I find it interesting that people don’t want to split the “signal“ with PushPull, but don’t mind splitting the “signal“ with a crossover??

 

[MrEd]

I find it interesting that people don’t want to split the “signal“ with PushPull, but don’t mind splitting the “signal“ with a crossover??

I have also grown to like simpler crossover filters.
The caveat is the drivers need be wide range and gentle roll off .
This also brings out the topic of love for single driver speakers and dht se amps.
Wonderful in their own way when done right.

 

[RPMac]

Is there a wide range that can go 20-20K???
Seems they all need help on top or bottom (most) or both.
My interpretation of what I’ve read from J-Rob and JE2A3 is to cover the music fundamentals with a single speaker that sounds correct….for me a 414. Providing help on top and bottom has got me to a place where I am very happy.

I lost my ability to listen all DHT…Paul-B may be getting a package soon.