I've been building two amps for the last seven years, one SE and one PP. As I develop one to the point where it surpasses the other I remove the older amp from my main system put it on the work bench.

I believe the ultimate potential for either topology far exceeds the abilities of %99.9 of the amateur and professional amp buliders out there (and I most certainly include myself in those ranks.)

The primary disadvantage of the SE topolgy is the SE ouput transformer. The comprimise needed to balance DC power handling and good primary inductance is painful. The parafeed connection (and thus no air gap) helps a lot - but it introduces the problems of (some would say the evils of) large coupling caps.

The primary disadvantage of PP amps is that real, honest to god, dynamic tube "matching" is very rare, and possibly fleeting, as the tubes age. CCS's help a lot, but they have their own issues and colorations and complexities.

The good news is that either one can sound great, and that it's a heck of a lot of fun building tube amps! It's fun, because for maybe $300 to $600 you can buid an amp (PP or SE) that, soundwise, kicks the doody out the huge majority of commercial offerings any price.

The amp at the link below has morphed from a simple little 6SL7 SRPP driver to 6N1P (parallel sections) parafeed transformer coupled driver, parafeed output. It sounds fantastic, but it can't match the bandwidth (bass and treble) and drive/punch I'm getting out of my PP amp. The PP amp pretty much matches the midrange.

Fun times, man!

TC

• My Original SE AMP

I have gotten an imense help from input gathered at litening meets. Both my own observations and from other participants. Discussion face to face with a shared listening experience is not available anywhere else.

Actually seeing how another circuit sounds is another bit of input. Seperating the small details from gross circuit changes is difficult. If it were easy, everybody would be doing it.

On large coupling caps, how big are they to cause you 'problems'? I like to use big ones in between stages. Moror-run Oilers of 1-2 uF. The current fav is a 1.5 uF MKV rated at 660vac. I got them on ebay for 30 cents each, delivered.
regards,
Douglas

I only brought up the "big caps" problem because it's a common prejudice among DIY folks, along with "transformers are bad," or "pentodes are bad" or whatever. I only agree with part of one of these: electrolytics sound bad in a power supply and the sound horrible in the direct signal chain. And the PS is almost always in the signal chain.

I use a lot of motor run caps, too, and I think they sound great with a good healthy signal. In a wimpy RC circuit (say 12ax7 or 6SL7 @ 1 or 2 m.a.) not so good.

Craft

Much less THD, with no regard to odd vs. even order and the different degrees to which people tend to be bothered by them. To say nothing of the fact that gobs of feedback are frequently applied to achieve silly low numbers at the expense of sound quality. Anybody still cherishing a Japanese receiver from the late '70s?

>>SETs have much more esp even order, hence they sound richer or fatter.

There's nothing rich or fat about a properly executed SET design driving a pair of suitable loudspeakers. I don't think gross and misleading generalizations do much to advance our collective state of enlightenment regarding the audio arts. . . .

A fat tone is pleasant. I think you yourself said that in the post above.

I agree with you...gross and misleading generalizations are gross.... I am sorry you think that describing a design characteristic is a generalization.

I don't want to get into a feedback debate since I am not an electrical engineer and not really interested in debating anyone on this forum. However, if you are really interested, I can point you to some refereed articles in JAES on the subject.

-akhilesh

• REc Dot Audio FAQ describing terms used to describe sounds

Just to make sure you understand I am not attacking SETs in any way..in fact I quite like the little things!
-akhilesh

While I don't think I'llfind a SE amp I'd rather live with, there remains that possibility. I am quite interested in trying to figure out a means of quantifying what it is I like and dislike about *ANY* given topology.

Just because a subject happens to be something the participants are passionate about, does not exclude them from participating in a gentlemanly fashion( whilst not PC to use such sexist nomencalture, the meaning is not quite conveyed with any other I could think of ).
regards,
Douglas

"Fat: See Full and Warm. Or, *spatially diffuse* - a sound is
panned to one channel, delayed, and then the delayed sound is
panned to the other channel. Or, *slightly distorted* with analog
tape distortion or tube distortion."

Guitar players value tube gear in attaining a particular kind of tone in playing, not reproducing music. That doesn't really do it, either.

I don't think one needs to be an EE to hear the effects of feedback. It's necessary in non-triode amplicification, as most other devices are distinctly non-linear and need a little help. It's necessary when driving long cables. Outside of that, it's a music killer. The Audio Note M2 has switchable feedback. Choose what you like. Without it, the music flows free, full and lifelike. With it, the life is squeezed out of the signal, and the music falls very flat. but I digress; this is about push-pull vs single-ended amplification.

I guess, in the end, I don't see much point in debating this unless the participants can be in the same place listening to gear that embraces the opposing viewpoints, so I'll withdraw.