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Tube experts ---Chime In Do BK testers Lie?

Recently I ordered 50 Sovtek 6550 tubes from a seller on ebay. I later found out the seller was a former employee of Audio Research who bought their stock of 6550s which were overstock from the 90s and never used.

I received the first box of 25 tubes and using my tube tester, a BK DynaJet, about 18 of 25 of the tubes tested in the questionable range. I emailed the seller and he said, the tubes were good, he has sold thousands to others who have re-sold them, and I was the only person who complained.

I was waiting for my 2nd box of 25, and he suggested I use another tube tester since mine may be wrong and is not very good. I recd the 2nd box of 25 and took now 50 tubes to a local electronics store and used their BK DynaJet 707, which is a machine they test all their tubes on....

Box 1---on their tester, now 20 of 25 tested "questionable"
Box 2-19 of 25 tested "questionable" on their tester.

I email the seller who now sort of alleges that even though I claim I have 20 years of tube experience, I don't sound like it. He offered a refund, less my shipping costs to and from, less my PayPal fees. I lost about $80 on the deal.

I get my refund today and read his PayPal remarks, and in bold, he claims all the tubes I sent him test NEW on his Hickok tester. for a fact, there were at least 3 which were plain DEAD on both my testers...

My question, do you think BK testers can test a tube to be bad, when in fact they are not? Does BK tube testers have issues with testing 6550s?,

I am glad to get past this situation, but really am a bit peeved at this seller, I was only telling it like it is for my perspective and 2 tube testers results.
128x128justlisten
justlisten's avatar
justlisten OP
489 posts
 
thanks for the replies, I too agree that seeing how I got some tubes of the same lot to fall within the "good" range, this would show the B@K can pass a 6550.....but as Albert points out, he has experience that a B@K will fail what a Hickok will pass. This is what the seller said. The second tester may have been a B@K 747, I think I have a B@K 707.

I do have some used GE 6550a which I bought as "used" from anothee AGON member and those test well into the "good" range of my tester.

Again, I am just glad I cut my losses and use the tried and true tube dealers.
avguygeorge
2,300 posts
 
Just thought I'd chime in re. some EL34's;bought as NOS. The sad thing is these tubes with questionable results cost me 3x's as much, as they take out the bias resistor/s. Ya gotta be careful and think of potential damage to your amp;forget about sound quality and life of the tubes itself. Then we have some amps where a bad tube can damage much more than a bias resistor.
hirsch9000
7 posts
 
B&K testers do not "lie", per se, but very few testers tell all of the truth. The Hickok and B&K's probably use different bias voltages, different test voltages, different frequencies of the test signal, and perhaps are testing different parameters. I use a B&K 747 and Heathkit TT-1A. The Heathkit is almost certainly the more "accurate" tester, yet I use the B&K most of the time. If a tube is borderline, the B&K will often reject it, while the Heathkit might let it through. But do I want borderline tubes in my amps? Not really. I'll risk false negatives with the B&K, simply because they are less risky than false positives with the Heathkit.
dlstephenson
121 posts
 
I have gone back to KNOWN sources for tubes as almost all the tubes that I have purchased "WHOLESALE" have been questionable. But when I really think about it, how many individuals in the current market can get outstanding tubes test them and sell them cheap?
uppermidfi
277 posts
 
justlisten, I would rather have the tester that was the most strict about what it passes. If there is a question about the quality of a tube - you don't want that tube, or at least,I don't. Too bad you lost money on the deal, but in the long run you're better of without those tubes.
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