I bought a single lot of about 40 6v6 tubes on ebay once. Only 2 types of boxes with similar red and black print. "Standard Brand" and "Quality Brand." Inside the boxes was a vast array of brands and usage levels and idle characteristics and (mis)behavior. Each was marked with “lab tested used.” (Not “lab testing used.”) Some were clearly NOS. I guess they were gathering tubes from wherever and testing and boxing them for sale.
It was fun testing, culling, grading and guessing the manufacturers. I learned about “screen glow” and arcing and damaged-grid runaway. I now have about 32 that will last my lifetime.
Don’t judge a tube by its box.
It was fun testing, culling, grading and guessing the manufacturers. I learned about “screen glow” and arcing and damaged-grid runaway. I now have about 32 that will last my lifetime.
Don’t judge a tube by its box.
When I was a kid with big guitar amp dreams, and no money a friend told me about the Eagle Army Navy store. They sold tubes. Cheap tubes. New in the box tubes priced from $0.25 to $1.00, yes a brand new in the box Thoro Test 6L6GC was $1.00. I saved my money, bought a pair and put together one of the loudest guitar amps that I had ever made. Hey, I was about 14 years old at the time. That pair of tubes lasted me several years. Later I would show my creation to another friend, who explained where the tubes came from.
When GE made a batch of tubes, they would pull several samples from the batch, and run them through some sort of quality control testing. If a certain number of defects were found, the entire batch would be rejected and sold off to a rebrander. This is why you will find tubes that are obviously GE made, with the "GE dots," but no other GE markings, with brands like Thoro Test, Best Test, or Lindal. These rebranders were supposed to test every tube and reject the bad ones. Did they? I don't know, but I did learn not to buy the Chinese 6L6GC's on Ebay for $4 each. Some work, some don't, but good ones were going for about $10 at the time from AES.
I looked through the few boxes of tubes sitting nearby. There are several "Standard Brand" boxes, all in green and black ink, quite old. Each contained a branded tube, Tung Sol, RCA, Sylvania or GE. No obvious signs of use.
There were two "Quality Brand" boxes. One contained an RCA made tube with smeared unreadable reddish paint lettering on the phenolic base. The other contained an RCA made tube branded "Delta" and the words "Lab Tested Used" and "Made In USA" poorly screened on the base in yellow paint.
When GE made a batch of tubes, they would pull several samples from the batch, and run them through some sort of quality control testing. If a certain number of defects were found, the entire batch would be rejected and sold off to a rebrander. This is why you will find tubes that are obviously GE made, with the "GE dots," but no other GE markings, with brands like Thoro Test, Best Test, or Lindal. These rebranders were supposed to test every tube and reject the bad ones. Did they? I don't know, but I did learn not to buy the Chinese 6L6GC's on Ebay for $4 each. Some work, some don't, but good ones were going for about $10 at the time from AES.
I looked through the few boxes of tubes sitting nearby. There are several "Standard Brand" boxes, all in green and black ink, quite old. Each contained a branded tube, Tung Sol, RCA, Sylvania or GE. No obvious signs of use.
There were two "Quality Brand" boxes. One contained an RCA made tube with smeared unreadable reddish paint lettering on the phenolic base. The other contained an RCA made tube branded "Delta" and the words "Lab Tested Used" and "Made In USA" poorly screened on the base in yellow paint.
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You should be acting like a true detective acts. And, of course, some technical equipment is necessary. If you want to detect fake tubes or unreal NOS, you have to be smarter than the seller and with a great experience in tube buying business.
A good technician can not be fooled with the electrical data coming from a parametric tube tester, such as the Russian L3-3, but you have zero chances with a Hickock or any other "quick" tester.
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There is no tube tester in the world that tells you if a tube is new old stock. Readings on new tubes are all over the place. A certain range of readings qualify as within spec.
I've had used tubes that measured better than guaranteed fresh ones (like JJs out of the box) and the other way around. The one issue for me is, that I somehow don't trust the measurements of dealers I don't know.
I have an L3-3 but these can be completely off as any tester. Often I test with cobbled together power supplies and meters.
I've had used tubes that measured better than guaranteed fresh ones (like JJs out of the box) and the other way around. The one issue for me is, that I somehow don't trust the measurements of dealers I don't know.
I have an L3-3 but these can be completely off as any tester. Often I test with cobbled together power supplies and meters.
I ask again: how? There is no known test for NOS i.e. hours of life used. There is no known test for 'hours of life left' either. The only tests are 'meets spec' (could be NOS or used) and 'meets spec with slightly reduced heater voltage' (so has some life left - but nobody knows how much).Schmitz77 said:
Shield, Triad. Not sure where Channel Master fits in. Not sure if Rad Tel was a real rebrander, or a box maker.
National and IEC - can be anything on the box, the tube inside may or may not be what it is marked as.
Standard and (Reliable) Selectron were just box makers, I think. Anyone could buy the boxes and put their tubes in, new or used.
I have some RCA tubes that are in styrofoam production flats, but most of the production flats I have are the grid type. I remember when you could get a NOS production flat for twenty or twenty five bucks, doesn't seem that long ago.
Win W5JAG
There are some strong indications to achieve evidence whether a tube is real NOS or used.
- Those tubes that everybody is looking for, are generally NOT for sale in new boxes, in high quantities, for low prices by a new and unknown seller in a far away country, with lot's of positive feedback. Sometimes yes, but most of the time not. If you have this strange feeling not to trust it, the OBVIOUS things will not help you. So of course, the optics is nice, and of course he ships sooo fast, and he is such a nice person. Better is when he writes he accepts return shipments.
- A good technician can not be fooled with the electrical data coming from a parametric tube tester, such as the Russian L3-3, but you have zero chances with a Hickock or any other "quick" tester.
- Balancing. Double triodes that are balanced by default, like ECC801S 802S and 803S, should of course not come out of the box unbalanced.
- The "feel" of real old glass which has never been heated since 60 years. I don't know why, but the glass surface gets a typical feeling from decades of storage. It is a bit "oily" feeling, though it is not oil of course. You can polish this off with a cloth, but then it is gone of course. Also it disappears after heating up the tubes for the first time. Particularly this oily feeling develops nicely in a colder room. So when I spot this "feeling" I know it is real NOS.
- The smell (1). Use your nose it really is a good thing This is working nice with tube testers that can heat up the tube under full dissipation. Like again the L3-3, and not like a Hickok or even lower class testers. Whatever this curious layer is, it evaporates directly at the first heat up. So I set the tube to maximum dissipation, and while it heats up, you try to smell it. For 1 half a minute the tube produces an "old" smell. You don't need a nose like a police dog for that. Just smell a tube that is really NOS, never switched on before, and it produces a smell sample like "old paper" or like a "humid basement". The smell is extremely typical, but of course it comes only once and only for seconds. After you evaporated that layer, it is gone, also the oily feeling is gone. Sometimes there is a flash of vinegar smell when the glass heats up first time after 50 years.
- The smell (2). There is the smell of a tube box from the 1950's, it is definitely another one as from the 1980's. Paper detoriates over time a lot, and the smell of that detoriation is characteristic for me. Do it like this: Remove the tube, and then breath slowly inside the box via your nose. Simply slowly and just five seconds. This will put some warm and some humid air in the box. Then with your nose still on the box, sniff in this air but not slowly. Sniff it in short and fast. You will smell how if the boxes are really old, and if so how they were stored. You need to practice a little bit with that. Quickly you will learn to keep apart old and re-printed boxes with 100% precision. Even you can say how they were stored: Dry or humid. If stored dry, the small has a flash of vanilla or fresh wood, call it a good smell. If stored humid, the smell is more like old stones, like an old basement. If there was fungus in the storage room, you can learn to recognize too. As I said, you need some practice, comparing many boxes, but this is really good, hidden information, and impossible to fake.
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As you may have noticed, there are SEVERAL factors combined who makes the statement clear, whether a tube is real NOS or not.
I have not only written on the SMELL of tube boxes, but maybe you have missed that part of the longer post.
You may still think its impossible to detect a true NOS tube, but for a real expert its possible with 99% certainty.
You are free to write a compendium of your criterias instead of criticicing other members who gave their knowledge to the forum.
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When I'm not mistaken this is from Jac's NOS page, right?
What does it even matter, if the tubes are "true old stock"? I've had guaranteed NOS tubes (military pack, sealed envelope) that tested worse than ones I had used for two years already. Tested on my L3-3.
The core issue might be how trustworthy the readings of tubetesters are and a simple emission test done with a powersupply and a digital current meter might at least seem correct.
Some types of tubes are known to be trouble, like globe 866Jr; with these I've had a 8/10 failure (broken filaments, arc overs) rate.
I am still waiting for a description of how a "real expert" can do electrical tests to distinguish NOS from used. Given the wide tolerances of valve manufacture an unused valve could give much worse test results than a used one.
I have already given one of my criteria: glass colour - and admitted that it is not foolproof. I have several times asked you to share your "knowledge" of electrical tests, but you simply repeat a vague claim that you can do what everyone else says is impossible.Schmitz77 said:
Well, selling tubes isn't really a problem. Selling tubes to audiophiles can be exasperating.
It's probably been five or six years since I sold any tubes on eBay. I do not describe tubes as NOS, even when they clearly are. I just post my TV-7 test readings, a vague comment that it looks unused ( unless it is used, and then this is stated ), and as-is.
I used to drag a few thousand tubes to hamfests to sell; I always put out some Telefunken 12AX7 as bait. When somebody reaches for those, I know it's an audiophile. Hams around here don't care ( I don't even like them, personally, or those EI's that were built on their tools ).
Win W5JAG
You seem not to be aware, that your questioning spin round in a vicious circle.
Youself have argumented that no electrical test can proove the NOS state of tubes. I have explained in length, that only a combination of methods can deliver NEARLY FULL certainty. But still you are accepting only electrical test methods as a prooven method.
Are you aware, sir, that your arguments going straight against mine and are nothing but absurd? Thats why I said that a further discussion is pointless.
But you couldnt accept or understand mentally whats going on here and still must have the last word.
My test system is comcludent and works well. So I see no reason, why I have been "backed down" on a topic, which gives excellent results, at least to me. Its been quite a while ago when I purchased a tube that wasnt exactly that which I aimed to buy. And that means real NOS tube, no fake tubes and no NOS tubes that are in truth just tubes without original box and used ones. So this all works with quite good results but it has taken a while (to be exact, nearly 40 years) to have achieved the knowledge and experience. I dont know how much experience is yours, but Ill just answer questions about NOS tube buying. Need nobody to tell me how to do it. That might be the big difference between us. So long.
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