NOS (New Old Stock)
NOS stands for New Old Stock: tubes that
where made a long time ago but never used. There is no official rule for
how old a tube has to be to become NOS, but most of the time it is applied
on tubes that were built either in the US or Europe until the mid 80's
(when the production stopped).You also have Old Stock tubes, which are the
same as NOS but but these are used.
The quality of the tubes is not affected when they just lay around doing nothing. As long as the pins are not suffering from oxidation, which rarely is the case. Many people prefer NOS over current production tubes, simple because back then they used higher quality materials and in most cases higher standards. Many of today's production tubes are built on machines that were used by the big companies (like Philips and Telefunken) many years before.
Right now there are only a few factories left that produce tubes and they are all based in Eastern Europe (JJ in Czech Rep. and Ei in Yugoslavia), Russia (Svetlana in St Petersburg and Sovtek) or in China (Sino). And only JJ and Svetlana are capable of producing tubes that come "close" in tone and quality when compared to NOS tubes.
Although Ei, for example, uses great Philips machines and are capable of producing a ECC83/12AX7 preamp tube that is based on the famous Telefunkens, it sounds really good but it's quality is so poor that it will go microphonic in any guitar amp. And thus renders is useless for 99% of it's for us guitar players. Too bad cause the sound is really good, especially when used for high gain application, but the microphonics are aw full.
Some people like the newer Sovteks and their Electro Harmonix tubes. These are certainly better then their production in the 90's but imo not as good sounding as JJ's or Svetlana and for from NOS tubes. And Chinese tubes... well I'll leave that to the people who can only dial their gain to 10.
The following article
was written by Myles Rose of
NOS TUBES – The hype, myth, and reality.
Today’s new tubes are very inconsistent. Their specs run plus
to minus 50%. They are not linear (those plate alloys react differently as
the frequency changes and heat changes for one thing), and they do not
meet specification that were established in 1957. They may meet one spec.,
but only if you are lucky.
Recently I tested some new Sovtek 12AX7LPS
tubes. These brought this subject home. Using a myriad of test equipment,
it was found that in one area, these tubes did beautifully. This area was
simple gain. Using the Vacuum Tube Valley small tube characterizer, these
tubes produced the “gain” of 100 or over a bit in some cases, just as a
12X7 should. BUT … a tube has more than one factor.
NOS for one thing is a short term option. Short term? Sure, this is limited stock. The reason the 50’s tubes fare better than the 60’s tubes in some cases, and the 60’s better than the 70’s, and so on, was that in the 50’s, more tubes were used for critical applications. They had better metals and QA.
There are some points of light on the horizon too.
Well, thankfully, the Chinese have money and are putting it into consistency. They see the economics of the music business as a strong market with MTV, VH1, CMT, and more amp makers than ever before in music history. Each Chinese batch of 12AX7’s is better than the next. Their “torque and acceleration” are currently better and closer than any of the Europe tubes generally. Their consistency is also the highest.
The last hope lies in the hands of folks like Aspen Pittman (Groove Tubes). GT spent a LOT of money to remake a tube called the 6L6GE as an example. This was not an easy task, taking years. Using the original tooling was not all that hard (Aspen just bought it from a factory when it shut down), but setting it up properly was another costly story. Then the daunting tasks of those materials in the recipe was the issue. Well, he pulled it off, after many years and many dollars. We now have a great NVM ( I coined that NVM by the way … new vintage manufacture) output tube. It is not cheap, but it can be produced over and over now. I am not too worried personally on how long this tube can be produced, as I am 53, and I saw enough tonnage of original plate material metal to make enough of these to last at least my lifetime!
There are other folks that work directly with some of the major tube factories. Some do this for a love of tone and amps, such as Aspen, some do it for economics. The folks that do this for economic reasons seem to take shortcuts which show up in the end result product, as is the case in some of today’s preamp tubes.
When it comes to new preamp tubes, keep in mind that today you have gain … although all over the scale and inconsistent. You rarely have the other factors, output and TC. If you know your preamp tube vendor, your chances with new tubes are much better. GT, as an example, tosses about 50% of their tubes, as they have to meet tests for output, low noise, and a lack of microphonics. That is part of the reason for their cost that some folks feel is higher than some untested tubes.
The bottom line here, is that NOS tubes were superior to the products made today. If you cannot hear this and FEEL this, turn down your gain, raise your master, maybe learn what to listen for, and perhaps have your ears cleaned.
If after all that, you still feel there is not a difference, then you are fortunate to have standards which are easily met. BUT …. You still cannot escape the basic math and seeing that the data on today’s tubes do not meet those of yesterday unless you have a vendor that will go through 1000 of them to find a few great ones.
P.S. I have called and written Tone Quest a few times. I have a number of friends and associates that are on their advisory board, and I was thinking that they may be interested in some real tube info, which at times is lacking in their publication. I guess my personal clients are not obscure enough for them, or perhaps there may be some other reason they do not return phone calls or emails. In any case, if there is somebody that may know why they are not interested in some tube information, maybe you can let me know as they don't seem to have the time to respond.
Myles - Guitaramplifierblueprinting.