New to tubes-what the heck does NOS mean?

I checked 50 posts in the forum and saw many references to "NOS" but didn't see what it stands for. Tell me please?
Also, any opinions on good values in EL34 tubes? I've read some good things about EH (Electro-Harmonix) being a good output tube VALUE. Your comments based on actual listening experiences are appreciated.
Thanks and happy listening!
New OLD Stock . . Vintage or old tubes of suposed higher quality. If you are willing to spend a litle more contact kevin He will sell you the best thoroughly tested tubes . He is not the cheapest but one of the best .
NOS stands for "new, old stock" The tubes have never been used but they are not newly made (read: not as good). Some people prefer tubes from a certain manufacturer and from a certain time range rather than brand new, just made tubes. Personally I prefer Krell tubes.
I believe it means "New Old Stock"
NOS means new old stock: new tubes produced mostly 30 to 40 years ago (before the transistor-age).
Buyer Beware. Be careful lots of old out of spec tubes being sold as NOS. They ar NOS but where not to factory spec. Being passed of as the OLD Classics. They have the name but not the sound.
Thanks all for that NOS information!
Your continued comments about EL34 output tubes are apprecited.
Happy Listening!
I thought it was Never On Sunday. You mean i've been giving them a day of rest all these years for nothing? I guess I have to read the manual again.

I remain
new old stock. the reason that nos tubes, for the most part sound better and last longer is because of the vacuum pulled on the tube in the manufacturing process. because of current high production rates vs nos tubes "they were allowed the time to pull a stronger and longer vacuum".
buy your tubes here, Vintage Tube Services, I found him to be WAY more friendly and helpful than Kevin Deal (at Upscale).

His tubes are just as well tested and he will talk and help.
Many prefer the descriptor "new original stock" to the above definition avoiding the oxymoron.
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.

I use Electro-Harmonix EL-34's in my VTL Deluxe 225 monoblock amps. They have excellent sonics.
Check out 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.
NOS, new, old stock. this was originally coined by the car manufacturers, on parts that were new but were over seven
years of age. When I was restoring my 1960 Ford Starliner, I replaced most of my chrome with NOS parts rather than reproduction parts, it took forever and some very strange places in the US to find them, but they were out there. It is amazing what people will hoard. And it ain't cheap either!!!!
Shubertmaniac, my first car was a red '60 Starliner. That's one rare piece today. A drunk hit my car head on while it was parked in front of my parents house and it was totaled. I'd sure like to see a photo of it. Also, you are right on with the description of the auto manufacturers coining the phrase new old stock.
eh el34 tubes are exact replica of mullards but much cheaper and affordable. they're made in russia, have an outstanding longetivity and quality.
sonically they're softer than svetlana but have greater and deeper bass.
An Intro to NOS tubes: This Article on NOS tubes is a nice intro.

I have an outline of online tube articles if anybody is interested. It is aimed at the diy folks but has some other stuff too.

I remain