New to tubes-what the heck does NOS mean?

Tim -

there's a lot more to it than how strong of a vacuum was pulled. Cathode coating mix, design, manufacturing skills, many tricks of the trade that are now long lost forever. All of these contribute to the difference between NOS tubes and current manufacture. I was an unbeliever initially until I tried old tubes for the first time. Now I have thousands of them.

-Ed

I use Electro-Harmonix EL-34's in my VTL Deluxe 225 monoblock amps. They have excellent sonics.
Check out http://www.thetubestore.com/ for a good selection of these and others.

Ed -- THOUSANDS? I've got eight.... Think of it this way, once upon a time, the large majority of military hardware was dependent these tubes. Consequently, a good bit of the best minds and vast military-industrial complexes of the world were devoted to making the best tubes conceivable, at any cost. Now, at that time, due in part to the (im)precision of manufacturing, making tubes was at least equal parts art and science. Today, the guys who perfected the "art" component of it all are mostly not around or just not doing it any more, so -- to an appreciably real extent -- the art of making vacuum tubes developed at the height of the cold war is a bona fide "lost art." The literal life and death urgency to making perfect tubes is gone, and there is nothing that will bring both the resources and talent back into the equation. Now, you could easily argue that modern advances in precision manufacturing can and have more than made up for any supposed lost "art" in making tubes, and that modern tube making (although an esoteric and fringe industry, to be sure) is more than up to the task. Listen to both and decide for yourself. One thing is sure, though, (whether it is through massive, consensual group delusion or some objective, quantifiable truth) enough people believe that there was some sonic magic captured in the tubes made back in the day that hasn’t been equaled in the current batches. Luckily, again because they were just so damn important at the time, folks made a lot of extra tubes back then and stockpiled them, which is why there are New Old Stock (made then, yet unused) around on the market. I’ve got Mullard gold pin MIL SPEC (“Military Specification,” I assume) NATO tubes in on of my preamps that came in the original NATO packaging. Hey, even if they didn’t sound better (and they do), that’s pretty cool.

I like to second "thetubestore". I've been using the Svetlana EL-34's in my Marshall and Laney amps and E-H's EL84's in my 'class A' Vox and Laney all with great results. Other tubes purchased from this store were for Mesa-Boogie and Hi-Watt amps.