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I see lots of NOS tubes on Ebay even new in box that show discoloration of the pin, frequently a different color half way up. What's up with that. If really new wouldn't the color be even on the whole pin? Thanks, Tweaker
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It is all very interesting!??
I've bought sealed boxes of TFNK E88CC, open the box and discovered classic ink stain. However each triode checked out identical to the other. All of the other boxes I bought in that batch looked the same and checked out identically.
Were the tubes NOS? Dunno? Didn't care. They checked as new, and wound up all being matched?!
For a while I used a tube checker that simulated an audio circuit, used a 1Kc signal and indicated gain in dbs. Some NOS tubes seemed to be 1db down from others. I don't worry about 1db. When selling those tubes some people would pass on the tube since it was 1db down.
Since a tube can be used for more than one purpose, and tube tester specs seem to be generated for what purpose the tube was made for, I've often wondered of what relevance are the old tube checker measurements to how the function in the buyer's gear he intends to use the tube?
I believe 6DJ8 was made for cascode VHF amplification? One triode feeds the other for VHF amplification.
How relevant is testing a tube to do that for whatever the audio usage is?
Dunno.
What is interesting is that no relevant measurements have surfaced that are related to how a tube functions in circuits designed for different purposes.
No guide lines from manufacture's.
No guides, that I'm aware of, to help judge when a tube is suited for different generalized circuits.
I'm guessing that in many circuits a used tube will function just as well as a NOS, and probably for just as long, or almost as long. If a tube's life time is 10,000 hours, and a used tube will last 9,500 or 9,000 hours at some lower price than a NOS commands their economic benefits are identical. At an even lower price the used tube offers a better bang for the electrons!!
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
Most of my tubes have discoloration on their pins. It's very common. There are a number of people selling tubes that are reputable (myself included: kscollectibles on ebay).
If you are referring to tubes with bases then it's likely the soldering process in manufacturing. Meaning when the tube wires are soldered through the bottoms of the hollow pins. The solder and heat would result in discoloration. That's my guess?
Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
Pins are discolored quite often on brand new old stock tubes. That is NOT a reliable way to tell if a tube has been used.
That's all I'm going to say. Buy tubes from a reputable source and you have no worries. Otherwise you're going to quickly find there is essentially NO WAY to tell if a tube is brand new or lightly used and it's your risk.
I'm sorry if that seems harsh, but this discussion has surfaced SO many times that there's no point in rehashing it.
Jim McShane and Kevin Deal (Upscale Audio).
That's about it.
"To Learn Who Rules Over You, Simply Find Out Who You Are Not Allowed to Criticize."
-Voltaire
I'll second Jim McShane and Kevin Deal. Also EveAnna Manley.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
I've purchased many a tube from them. Since I have but one backup set of SED tubes for my amps, I ordered online another sweet sixteen while they were still available. I received an email telling me:
"The last batch of these tubes to come from the factory prior to shutting down exhibit a "soft vacuum," which causes them to fail prematurely when they are pushed hard."
They recommended alternates, but since I was interested in one last chance for SEDs, they allowed me to cancel the order.
Honesty is truly the best policy.
The latest prod dates of SED Winged C 6550s 2011s don't measure very strong and I've had a few lose vaccuum entirely. Upscale was good about it when it happened.
Edits: 02/27/16
Different personalities though. Don't expect Kevin to be Jim. 😎
"It's all fun and games until someone doesn't pick up on the sarcasm"
Edits: 02/26/16
NO WAY to tell if a tube is brand new or lightly used and it's your risk.
Thats way there is so many NOS/NIB Tubes sellers in ebay...
Impossible to tell if a tube is NOS unless you have kept track of it over 50 years or it is in a factory sealed carton. A seller should say it tests at NOS levels rather than claim it is NOS.
Wasn't a big deal when buying $5 NOS tubes 10 years ago. Some were NOS some were not, whatever. But if you are looking to shell out $100s for a NOS tube, you might want to find a legitimate seller rather than a generic "found these in grampa's attic" dude.
By the way, looking at "pin color" tells you nothing. Heavy scraping can tell you it was inserted in something, otherwise pin color says more about storage conditions and how the box was interacting with the pins over the last 50 or 60 years.
I bought tubes on eBay many times in the past. Some sellers are reliable. Others are not. Unless you only find what you're looking for
there AND the seller has plenty of good feedbacks, keep shopping.
I take all claims of "NOS" with a grain of salt. Occasionally you do stumble on the real deal at old TV repair shops and the like but that is very rare. I would not trust ANYTHING from ebay to be true NOS.
I prefer to buy (used) test as NOS tubes from reliable suppliers. The best sources are local guys found at Hamfests or online locally that I can meet in person and bring my tube tester along. There are some reliable sellers on ebay and other internet sites like Jim McShane's, Canuck Audio and thetubestore. Some suppliers like Partsconnexion have actually let me come to their offices with my tester to make sure I was happy. There are good people in the tube business and if you find them they can be a treasure. Never argue price with people like this. Unfortunately there are also a lot of people out there just looking to make a fast buck any way they can. These are the people that give "NOS" tubes a bad name and scare people away from trying them. Very unfortunate.
.
"I can't compete with the dead" (Buck W. 2010)
"It would take me forever. I don't think I have forever" (Byrd 2015)
Knowning Byrd is a good idea, both from the standpoint of honesty and measurements.
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