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NOS tubes

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Just posted about the availability of NOS tubes . Remember in the what 1960's and 70's when most all tube manufacturers went out of business ? After that guys were scrapping the earth searching for tubes .

And somehow there is a healthy supply of NOS tubes all over the internet for sale ????? Things that make you go HMMMMMMMM .

cityjim

Follow Ups:

RE: NOS tubes - Palustris 14:57:58 05/27/09 (0)
Things that make me go HMMMMMMMM are posters that ask a question and then never get back to the thread to acknowledge those who have spent time posting an answer.
RE: NOS tubes - becketma@yahoo.com 22:42:59 05/26/09 (8)
The post made me go what?

Maybe I better go check the Eimac 8877s I bought in the 80s and 90s to make sure they are real mil surplus?

"He (R.M. Nixon) was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena, and the style of a poison toad." H. S. Thompson
- Agree... - Skylab 06:41:28 05/27/09 (7)
  I inherently distrust threads started by people who are not registered asylum users, unless the thread is in the form of a "please help me with X". Any thread started by a non member that is of this nature usually has some sort of agenda. I'm not saying that this is the case with this thread, but more often than not, it is.
  
  That said, some tubes obviously are NOS - still in the original box with absolutely no signs of use. They can be found, though I agree with popular tube types they are getting rarer, and I also agree there are a lot more people selling NOS tubes (on EBay) that likely are not.
  
  Rob
  "Let there be songs, to fill the air"
  - RE: Agree... - Donald North 12:19:31 05/27/09 (6)
    I purchased some tubes on Ebay that were advertised as NOS. I tested them on my Amplitrex tube tester and found they at 60-70% of what they should be to be new.
    
    I love the Amplitrex: With it, the BS ends here.
    
    Donald North
    - RE: Agree... - Jim McShane 16:18:09 05/28/09 (5)
      The problem with ANY tube tester is the fact that tube characteristics vary considerably from tube to tube - even the same brands/types/etc.
      Tubes follow the typical "bell curve" distribution model. While many tubes are near the center point and close to published spec, a good number fall at the edges of the "bell".
      Finding tubes at 60 or 70% (% of what - I'm not sure what the poster meant) means only that they are, well, at 60 or 70%! They may be new, unused tubes that simply fall at the low end of the tolerance range. No tube tester, Amplitrex, Hickok, AVO, or ??, can confirm if they are new or not - only how they test.
      
      Edits: 05/31/09
      - RE: Agree... - TUBOS 06:36:01 05/30/09 (4)
        
        In Reply to: RE: Agree... posted by Jim McShane on May 28, 2009 at 16:18:09
        
        Having just tested about 500 known NOS 6SN7 series using a HICKOK 1575B (Mil version of the 539B/C), some interesting results came to light -
        
        A - Transconductance generally ranged from about 2200 uMhos to
        3000 uMhos, with the center about 2500-2600 uMhos-
        data minimum being 1700 uMhos per roll chart.
        
        B - Among the 6SN7WGT/WGTA types, the older tubes ( 1950-1965)
        were consistently higher than the late 1970-1980's MIL stuff.
        
        C - Test data quite dependent on the AC voltmeter setting, as
        line voltage changes caused a shift in Gm and Ip readings.
        This is probably linked to changes in filament voltage
        and plate voltage during test (triodes sensitive to plate V)
        
        D - Even when the tube sections Gm matched, plate current varied
        by as much as 1 ma(generally closer to 0.4 Ma or less). Typical
        plate currents were in the range of 5+ mA to about 8 mA at
        the indicated 4.5 V grid bias point.
        The point being that just a Gm match is close, but not perfect.
        
        E - Jim McS is correct in that a tester can only do so much.
        A few obviously used tubes were also tested, with many at
        the low end but with some testing at the high end even with
        significant visual indications of use present.
        
        TUBOS
        
        RE: Agree... - becketma@yahoo.com 00:00:31 05/31/09 (0)
        
        In Reply to: RE: Agree... posted by TUBOS on May 30, 2009 at 06:36:01
        
        For audio use, I like a tube tester that measure small signal tubes in db gain. It puts things into perspective.
        
        One fellow wanted to buy some TFKN ECC88s. I made a nice matched pair of what I believe are/were mil surplus that I bought from Billington's a few years ago. They measured in the normal range for the hundreds of NOS ECC88s I've tested.
        
        He called me complaining that they only measured 70% on his tester. When I asked how he converted his test results into dbs there was silence. I discovered that he defined checks as NOS as 100% on his tester. That's a good way to buy champion tubes, but it gives a lot of false negatives. His view was 30% of the tube's life was gone.
        
        Since it was a small sale, and I knew that if I wanted to sell the tubes for more I could (he bought some 12AX7s and E88CCS also), I simply had him send them back for a refund.
        
        I still have those tubes. TFKN <> E88CC and ECC88s, which I use in my gear; they are worth more, in my hand, than buying some in the future.
        
        When I went to college and studied Marketing Research a little, I read a couple of papers that proved a Sigmoid response to risk under certainty. The curve was more pronounced under uncertainty.
        
        Getting HIGH prices for tubes that can be measured, even when the measurement is not related to how the tube is used, is a good example of how people are willing to spend a lot more to avoid the possibility of buying an under performing tube.
        
        After a while its easy to spot NOS tubes that aren't from the past but are recent production masquerading with an old name. I've still got a few Orange Amprex World Logo JAN E88CCs that are NOS, but they don't have gold pins, they have flying saucer getters and solid Russian type glass.
        
        Best from Hot Tucson
        Bob
        "He (R.M. Nixon) was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena, and the style of a poison toad." H. S. Thompson
        
        Fascinating! Thanks (nt) - Skylab 17:02:50 05/30/09 (0)
        
        In Reply to: RE: Agree... posted by TUBOS on May 30, 2009 at 06:36:01
        
        .
        
        Rob
        "Let there be songs, to fill the air"
        
        RE: Agree... - Jim McShane 12:34:23 05/30/09 (1)
        
        In Reply to: RE: Agree... posted by TUBOS on May 30, 2009 at 06:36:01
        
        Thanks for sharing that info!
        
        Just a couple comments if I may:
        
        1. Gm variance from 2200 to 3000 uMho is a difference of nearly 40%. That's typical, and is about the same as I find in other small signal NOS. It's also what I find in new production.
        
        2. 5 ma to 8 ma is a difference of 60%.
        
        I point these out because often I see comments about how new production tubes don't have the "tight specs" of NOS tubes. Well, 40% variance and 60% variance hardly qualify as "tight".
        
        I also appreciate you sharing this:
        
        "A few obviously used tubes were also tested, with many at the low end but with some testing at the high end even with significant visual indications of use present."
        
        SO true! Tester results - any tester - cannot be used as the sole criteria to judge a tube's "newness".
        
        Finally, you wrote:
        
        "...as line voltage changes caused a shift in Gm and Ip readings. This is probably linked to changes in filament voltage and plate voltage during test (triodes sensitive to plate V)"
        
        Yes! A very cogent comment, thanks for sharing it.
        
        Great post, very useful data - thanks again!
        
        RE: Agree... - TUBOS 18:45:26 05/31/09 (0)
        
        In Reply to: RE: Agree... posted by Jim McShane on May 30, 2009 at 12:34:23
        
        JIM McS -
        
        A bit more data re: your post -
        
        From a database of the first 400 US NOS 6SN7 tubes, the following
        added info -
        
        A - 19 sections tested below 2200 gm, with an average plate current
        for the lower testing section of 5.33 mA (4.4 mA min @ 2175;
        6.1 mA max (Gm not noted)
        
        B - 10 sections tested > 3000 Gm, with an average Ip of 8.3 mA,
        with one section testing at 4800 Gm / 9.8 Ma Ip
        
        Some of the test variance would probably fall within the
        2% reject rate factories allowed distributors in the 1960's.
        
        Among a group of older Japanese (13) and USSR (5) tubes (guess
        late 70's to mid 80's production), test results were about the
        same as the USA tubes.
        
        However, the section to section Gm and Ip were closer. Japanese
        tubes tested mostly 2400-2600 at about 6.6 mA. USSR ran closer to
        2750 at about 6.8 mA
        How current production tubes would compare I leave to your
        experience, as I have none to sample.
        
        The USM-118 (cardmatic) has regulated supplies and a wider range
        of test voltages, as does the Triplett 3444 series, the New London
        901A and the over-large RCA Lab unit, to name a few.
        A BOGEY (design center) tube should test at 75% on the USM-118
        (does NOT mean that the tube is at 75 % of the NEW value - I know
        know this, but I add the comment for others who may read this
        post).
        
        Test data is more reliable using these units - I just happened to
        use the Hickok unit for this test series, as Ip is easier to sense.
        
        When matching section to section, a TEK 570 and a computer are
        very handy. Alternately, a stairstep generator and a scope or
        "sample and hold voltmeter" system would work.
        Alternately, a properly configured DIFF AMP circuit with the
        proper instrumentation should work well to sense balance and
        perhaps tube noise as well.
        
        TUBOS
I believe you have your time line a little confused. - unclestu52 13:01:39 05/25/09 (1)
While it is true that Marantz and Mac basically ended their tube gear production in 1968, tubes did not disappear, and were the backbone of military gear even after. The GE plants did not shut down till the early 90's, IIRC. and some companies like Richardson (IIRC, they own Eimac and Cetron, among other things)actually still rebuild and manufacture new tubes, particularly for transmitting use. In fact, in my area there is only one television and radio station which uses transistorized outputs: the rest all use tubes.

While most Western nations have ceased production of tubes, the military had huge stockpiles, and these stockpiles were not deleted from their inventory until after the fall of the USSR in 1992. In 1995 we see a huge number of surplus sales not only in the US but throughout all NATO countries, and the SEATO countries also. In 1995, I recall a surplus sale in Ogden where the Air Force dumped 140,000 6189's, a 12AU7. I remember placing a bid of a dollar each tube for a pallet, but never won it ( good thing as what the hell would I have done with 10,000 tubes). In the same year or close to it, the Australian government dumped a large number of British type tubes, including KT-66. As recently as two years ago a British surplus depot had 400 genuine KT-88's for sale. I remember purchasing metal base 5AR4's from a Swedish source with Swedish military numbers on them. When Mt Pinatubo erupted and the US closed down Subic Bay in the Philippines, US surplus centers received a fairly large number of vacuum tubes. I distinctly remember seeing one lot with over 250 12AX7/5751's.

Some tubes like 807's which were workhorse tubes in WWII are plentiful because of their plate caps. Modern designers do not use them because of the liability factor so the millions made during the war years are still very plentiful because there is simply little demand for them.

Prior to the fall of the USSR, many American tube manufacturers had explored solid state desings. You see this in CJ and ARC. In fact the fall of the USSR pretty much coincides with the ending of the GE manufaturing, the last of the large American manufacturers. But the fall of the USSR also opens the doors of the West to Russian made tubes, which had never stopped behind the Iron curtain.

But there is no doubt that NOS tubes are drying up. The large caches from the cold war years have been sold and placed into general distribution. Yes you can still find NOS, but many are used and the truly new tubes which are desirable are climbing rapidly in price. The EBay listings of NOS tubes have dropped considerably over the past three years: significantly so by my observation and the prices have risen.

Stu
- An excellent and (in my expereince) accurate post - agattu 20:44:20 05/26/09 (0)
  I am a former DOD employee experienced with procurement and the ultimate disposition of military surplus tubes, which were ultimately auctioned. JAN Tung-Sol 6550 (3-holes)could be gotten for a song. Those (thousands) that weren't sold were crushed and tossed in the dumpster.
RE: NOS tubes - FenderLover 10:58:06 05/25/09 (0)
NOS tubes can have a life of their own, even before use. About ten years ago I sold a set of metal based RCA 7027A (kinda rare birds, even then). This year I received the SAME tubes, gratis, from a guy whose amp I help fix. They still had the same markings on them, that I applied ten years ago! In the same boxes.
Not really - Jack G 09:16:02 05/25/09 (0)
You have to remember, that tube manufacturers cranked out millions and millions of tubes in their time. Every piece of electronics had tubes. Everything. Everywhere. Every radio, every TV, computers (not for home use), everything. You also have to realize, that not every NOS tube sounds good. The better ones ARE getting harder to find, as they slowly get hunted to extinction. You want coin based 6SN7GTBs? sure, lots of them around cheap. Try finding a NOS Sylvania 6SN7W metal base, cheap or otherwise.
Jack
Not that I remember..... - doodlebug 08:53:04 05/25/09 (0)
I worked on a bench in a small stereo shop in the mid-70s. Back then, folks were trading in all their old tube gear for solid state stuff. The marketing of SS was such that the perceived value for tube gear hit rock bottom. My scrap room was filled with Scott, Fisher, Harmon Kardon amps of all sorts, shapes and sizes.

I had boxes of tubes we used to take out to the city dump and use for target practice on weekends. When I did get a tube amp in for repair, tubes were readily available through the local electronics distributor. No, we didn't worry much about tube matching or brand. A tube was a tube and you needed to be sure the amp met specs and that's about it - much like I looked at a solid state amp.

In eastern North Carolina, like many other parts of the US, the ability to network was indeed very limited. Since the majority of folks I sold to, met or otherwise worked on their gear felt that tubes were old-school, I didn't go out looking for the handfull of contrarians who felt that tube gear would come back - or never leave.

As for today, many of us from back then who have finally become wealthy enough to afford some of that tube gear we lusted for as kids are driving much of the tube demand, IMHO. The Internet makes it a lot easier to make it happen, too.

Cheers,

David
"all over the internet for sale" - Chris O 06:52:54 05/25/09 (1)
Exactly. Previously not an issue with the number of tubes, but an issue with making a market in tubes. The internet made vacuum tubes available. People had horded tubes and still do. In the old days they just sat because no garage sale would bring any money in tubes and no one was walking into the old electronic supply warehouse out in the middle of nowhere.

Now that there is the internet, you have every potential customer for tubes at your garage sale. Also, trade with Russia and China picked up (started in ernest) in the 1980s and 1990s. These are about the only places where new tubes are made now and those places were not an option in 1975.

___
Long Live Dr.Gizmo
- Yes; they don't call this the information age for nothing .... the words useless information - Cleantimestream 07:12:44 05/25/09 (0)
  are taking on new meaning though.
  "The Sound of One Hand Clapping is Crashing by Design" HKM

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