Why do old tubes sound better than current tubes?

I still think nostalgia is part of it.

Old tube gear had a certain sound different than modern gear. part of it was the tubes perhaps but also the overall state of eletronics design 50 years ago compared to now.

Old tubes in good condition still perhaps deliver that sound compared to more modern high end sounds.

The old tubes perhaps are more in the rhythm and smoothness camp and the newer ones more in the detail and resolution camp?

I'm sure there are exceptions, but that is my theory. I have too little actual experience with a variety of tubes these days to say for sure.

Similar to old low res TV versus newer HD TVs. You can see more details in HD but not everything is more beautiful in HD necessarily!

Tvad, Forgive me for not writing a book about my stuff and tube experience. No one would be interested, even you. Talk about a cost/benefit ratio! :-)

However if I see a post where I can knowledgably recommend a specific new production tube to get a specific result I will do so without regard to whether its old or new. And that is likely the only time I'll ever get into a discussion on the internet about what tubes I like (or not).

I was really doing nothing more than advocating that those who would come here seeking advise take less than very specific advise in response to very specific request with lots of cynicism. A poster should keep a mind open to all possibilities, including that in many applications new (or recent) production tubes can be, or are, as good as he needs in that specific application. IMHO, 'general' rules, broad observations, and general recommendations suck. Now for someone who can't do better than ask for 'What's Best' I'm sure that generic responses would be fine.

BTW, I realize that you have posted that you have not improved on NOS tubes in the applications you have changed tubes in. I take you at your word. But, consider for a moment that this statement really means little beyond the needs of your applications and the number of new (or recent production) tubes you tried as an alternative. Not so many I think IF you have been predisposed to a conclusion based on the age/expense/rarity/ of the tube or the hyper critical application you were using when you reached your conclusion.

Ciao

Tvad, You are right. I did read too much into it I think.

New production (or recent productions) I have found a place for:

SED 6550, SED EL34, SED 6L6GC, and SED KT88's (I really like SED's)

Re-Issue Tung-sol 6550 (in one amp)

JJ and NOS Tesla 6922's and JJ and NOS Tesla 12AX & 12AU7's. I like the NOS tesla's better, but not that much and they are hard to get and can be spendy.

EH6922's (one application so far - not universal by a mile).

Re-Issue Mullard 12AX7's (one application so far)

EI 12AX7E (long grey plate) - my go to NP 12ax7 as a starting point/reference. I really like this particular EI though I guess it is out of production. I've had no QC problems with this one either.
EI 6DJ8 but it is not as quiet or rugged as I like. Again it is no longer in production.
EI 6CG7 - the only new one in production. So far so good but I'm just starting an inquiry into this tube type for a specific amp but so far so good.

And, FWIW, I've got a few others that are still trying to find a good home. Curiosity may have killed the cat - so far I'm only limping! :-)