How come that NOS is better them NS new stock ?

One thing to keep in mind regarding NOS tubes. Most of what we call NOS tubes were made at a time when many countries were at war.The periods of the 40's and 50's saw production of German Siemens, Telefunkens etc.. as well as American tubes used in military applications for the Army and Navy. We see many of these tubes today as JAN labeled, HM for Hungarian Military in the case of Tungsrams, and other applications such as medical equipment Amperex(although much later 0n ..i.e. late 50's) found uses in domestic and foreign products where reliability was necessary for product sales..TV's radio's etc.. The fact that many NOS tubes were commissioned by Military forces to design a quiet, dead reliable,and long lasting valve for use in military radios, transmitters, and even jet aircraft. Many of the older Russian Mig jets used tubes in their radios in flight. Over the later years and as the political climates have changed, along with the proliferation of SS designs,many once thriving tube manufacturing plants were not able to keep quality control in their production of their tubes. The Russian Sovtek plant is a good example, and now has been bought by the American company New Sensor..who is now making fabulous tubes once again under the EH brand. Just FWIW..Enjoy the TUBES!!

This has been covered in detail both here and @ AA. Suffice to say these are the facts:

NOS are better, in basically all cases. (I have come across one new production tube that betters any NOS version, but that's it. And I have thousands of tubes.)

The quality of NOS will never be equalled again, for many reasons.

The prices are going to continue to go up, for NOS stuff. Every day there is one less mullard/amperex/etc. in the world - but never any more new ones.

Newbee, this is an uninformed opinion: "tube design is fairly well settled - not much new coming along." I have to disagree on that. There's quite a bit of new development going on in tube design. You won't see it from big commercial manufacturers though. It's all happening at the one-man-band level. Some of these things are new, others are re-discoveries of things known and done back in the 1920s and 30s and revived for modern use. But in fact I think if anything, more, not less, development and innovation is happening in tube audio than SS amps. The few 'new' things to SS are: The advent of so-called digital amps; Increased use of switch-mode power supplies by more manufacturers (not really new, just more in vogue now), The Gaincard (chip amps); and The Aleph line from Nelson Pass (among some of his other innovations). These are the only things I can think of in SS recently that can be considered somewhat 'new' at all. The 'new' things in tube audio are numerous enough that I don't have the energy to write them all down (and even then I am sure I'd miss some, there is so much.)

FWIW,
-Ed

I am curious, Ed. What is the single new production tube that beats all NOS versions?

Hi Sorlowski-

I suggest you go to www.vacuumtube.com. Place an order for The Vacuum Tube Valley Quarterly, Issue 19. Read the article “Why NOS Tubes Are Better”. This article provides and excellent discussion regarding NOS vs. new production tubes. This issue also contains a shootout for 6550/KT88 tubes in both guitar and hi-fi applications.

Regards,
Don

I believe I have read there are environmental considerations in the materials and practices of manufacturing tubes that weren't in place years ago (when the NOS tubes were made). This is not uncommon as air emission and materials waste disposal issues have a much larger impact on manufacturing than even 15 years ago. I remember just enough to be dangerous here, and cannot remember specifically what it was about the environmental considerations (maybe the use of lead or some other metal?), or how that would affect the quality of the tubes, so maybe some of the more tube-literate folks here can help out.