Why are older tubes so much sought after


What is it with old stock tubes?? They were made years ago and surely by now we have must learned something about making them. So why are some people searching for old tubes. I have a Shanling CD player and I actually think the stock tubes are better than the 395a tubes.
128x128blueranger
NOS tubes are compared with new production by listening to them. It seems to me that comparitive measurements of what the tubes do to the signal waveform could lead to an understanding of what needs to be changed in new production tubes to make them sound like the old ones which people prefer. The laws of physics haven't changed, so there is no reason that tubes made today can't be superior.
Eldartford- The reasons are, I "suppose" economic. Not enough demand to support the cost of higher quality materials, tooling, and labor.
I am not sure that you can get good engineers to work on tubes these days. People are what make products good or bad. If you are an EE, will you choose tube design as your career?

They did not even teach tubes when I was in the EE program, and that was a long time ago....
Again- Info on some of the precious few companies manufacturing tubes comparable to NOS quality/transparency, and the prices they are commanding: (http://www.kraudio.com click on "tubes")
(http://www.elusivedisc.com/products.asp?dept=1681)
(http://www.euroaudioteam.com The only company making quality small signal tubes now-click on EAT)
(http://www.westernelectric.com)
(http://thetubestore.com/wesel.html) I have to agree with the "economics/supply and demand" scenario as to why more aren't taking the time and effort to produce tubes as good as those(granted- the select "Grails" and certain choice others) from the 40's through the 60's.
Larryi,

I would agree with you. Manufacturers need a constant supply of reliable tubes that can be bought in bulk for a reasonable price.

I guess it is up to the individual to search and test which selection of tubes works best in whatever equipment. Though this can be tedious. I spent a lot of time and money trying out valves that were unsatisfactory. Though I felt good when I finally found the best combination.

I doubt very much that a good quality valve cannot be made today. Manufacturing techniques are far more advanced now. Unfortunately we are such a small market to cater for that it probably isnt worth tooling up for these days. Even so, we still run into the problem of which ones to remanufacture? Imagine remaking the bad sounding ones!

As someone said the laws of physics have not changed (yet! Maybe CERN will change this) so in theory performance can be copied or even bettered. Who knows? We live in the age of information. Everything we need is out there somewhere.

Wouldnt it be great if the equipment just worked at its finest performance level, rather than us wasting time listening to tubes. We could be listening to music or dealing with things of real importance like which cable sounds best? Aaagggg!