Mixing SE and push-pull

[Prune]

Excuse this newbie question, but:
Any thoughts about the sonic effects of having both SE and push-pull in the signal path? For example, my DAC's output stage is SE, and it feeds push-pull headphone tube amp. What about the reverse, first push-pull then SE?

[Brett]

Originally posted by Prune
Excuse this newbie question, but:
Any thoughts about the sonic effects of having both SE and push-pull in the signal path?

It can sound very good if done right. But IME, differential all the way sounds better.

What about the reverse, first push-pull then SE?

I'm not sure why you'd want to or need to. SE-PP has some applications where it's useful to do, but not the other way around.

[Prune]

Originally posted by Brett
I'm not sure why you'd want to or need to. SE-PP has some applications where it's useful to do, but not the other way around.

It's not that I would want to. What I meant was whether it should be a consideration when choosing equipment. For example, would the preamp being push-pull or SE matter when looking for an amp. And why.

[Brett]

Originally posted by Prune


It's not that I would want to. What I meant was whether it should be a consideration when choosing equipment. For example, would the preamp being push-pull or SE matter when looking for an amp. And why.

Most preamps wih a balanced output can be fed into a single ended amplifier input. It would depend on how the preamp was designed whether it made much of a sonic difference or not, allowing for common mode rejection in the power amp.

A well balanced system pre to power amp will give a large rejection of spurious signal such as hum etc that you won't get if you went balanced pre to single ended amp. The difference can be surprisingly large and audible even id there was no obvious hum present anyway.

[James D.]

Hi Brett,

SE-PP has some applications where it's useful to do, but not the other way around.

I found PP into SE a very useful option in that it can save an extra gain stage. My 845SE amp used a 6C45pi PP input/driver stage to give me the voltage gain with lots of current drive that makes the 845 happy in a two stage IT amplifier. I bet it sounds better than a three stage amp...

Though I agree that IT coupled PP throught sounds better still but I only had two 845s for my experiment!

ciao

James

[Brett]

Hi James,

As soon as I typed it I knew you'd pop in about your 6C45-845 amp. Because you need the tx to make it work, that makes it a 3 stage to my eyes

It is a very unusual and special case amp. If you didn't have the bits on hand, or had another pair of 845's, would you have used that topology?

Cheers
Brett

[James D.]

Hi Brett,

If you didn't have the bits on hand, or had another pair of 845's, would you have used that topology?

Ummm....

What a leading question! but your quite right, I came up with it to suit the parts I had. And that it worked so well was nice. I guess the proof is that the two 845s now reside in my Bass head...in PP

Interestingly I'm still using the bipolar power supply to the 845s but without the interstage, just cap coupled and I think I am getting some ground line modulation... I think I'll redesign the twin output stage of my bass head. (I noticed this when using the head as a voice PA amp.)

ciao

James

[fdegrove]

Hi,

It is a very unusual and special case amp.

Not so uncommon amongst Japanese audiophiles and once again a very good idea when executed properly.

Cheers,

[Paul Barker]

Steve Bench uses the PP driving SE topology.

[dhaen]

Hi Paul,

Welcome to the forum You'll like it here.

Cheers,