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Hello everybody,
I have a question: may I test vintage TungSol JAN-CTL-6SN7WGT tubes with Cary SLI-80? I used to buy 9 pcs of these tubes approx. 15 years ago from a reputable US dealer. I used them briefly for a couple of years, after which they've been kept in a drawer.
Recently I decided to sell them as I don't have suitable gear for them. I wrote an ad saying that I would invite to my place potential buyers with tube testers, since I have no capacity to test them.
We exchanged letters with a buyer living in other town, he purchased two tubes, but today suggested that one of them did not work and produced noise when powered on.
He suggested that I send him two replacement tubes, he would choose two tubes out of four and would send me back the rest. By now, I refused suggesting that he send me back two tubes and I would return his money.
My question is - can I test these tubes with Cary SLI-80 amp (which is the only tube amp I have) and if so, what bias current should I sewt? Or this could damage the TungSol JAN-CTL-6SN7WGT tubes or the Cary amp? I read somewhere that a Cary user used this amp with Russian 6p3SE tubes, which, roughly speaking, belong to the same family as the vintage Tung-Sol JAN-CTL-6SN7WGT/5881 tubes.
In the future, I will try to find a tech with a tube tester to test all these tubes and pick up their parameters, and only after that I'll post a new ad accompanied with measured parameters.
Any help will be much appreciated.
Follow Ups:
Oops -I made a mistake: I meant TungSol JAN-CTL 6L6WGB, not 6SN7WGT (copy-paste error)...
nt
Yes.
I'm sure the 6L6WGB and 5881 are interchangeable in many situations. However, the screen rating for the 6L6WGB is 300V, whereas it's 400V for both screen and anode in the 5881. So, almost the same, but the 5881 might be more appropriate for UL applications.
You're right - and the 6L6WGB screen rating of 300v was determined for "absolute maximum" rating, whereas the 5881 rating of 400v is a "design-center" rating.
Surely the screen rating for the 5881 would exceed 400v if determined as an absolute maximum value.
Thanks for pointing that out!
...and neither is acceptable for the Cary SLI-80 integrated, so I cannot demonstrate them using this amp. I brought them to a tech who measured them using a tube tester.
A couple of points that I might make for you in this case:
1: selling used tubes, especially w/ out a tester - As is, where is.
In other words, the tubes worked when I last used them, they have not been plugged into equipment since, and so should be in good (or excellent, or whatever you want to claim) shape (based on your last listen).
2: 'Did not work and produced a noise' Incompatible statement. If it did not work, it would not generate a noise.
3: '6p3SE tubes, which, roughly speaking, belong to the same family as the vintage Tung-Sol JAN-CTL-6SN7WGT/5881 tubes.' The Russian 6p3SE is a power tube, and often used as a 6L6 equiv. - like the 5881.
The 6SN7 is a medium mu, dual triode and used as either a driver tube for a power amp or a pre-amp tube - low level signal amplification.
Per the RCA receiving tube manual, Class A operation, Bias is 20mA.
IT IS NOT AN OUTPUT TUBE, and should not be used in the output section of ANY amplifier.
Feel free to reach out with any questions
Happy Listening
Thanks a lot, your comments are very useful.
As for his statement 'Did not work and produced a noise' -it was my awkward translation. What he actually said was 'One does not play and clicks when [the amp?] is switched on.' Is it still an incompatible statement?
Hard to say-
I am not that familiar w/ the amp-
however all tubes can make some noise on warm-up and cool down due to thermal expansion - some are noisier than others - Octals tend to make more noise than 9-pin bottles-
as a 'driver' tube between the pre amp section and the output tubes, it has a simple job - to give the signal enough boost to ride the power tubes to the Output transformers thence to the speakers-
the tube should work (as sitting in a drawer for 10 or 50 years does not change the tube, and they worked well before)
you may have a picky customer who is looking for a quieter / better(?) tube...
hard to know or to please-
I am sure you sold it for a reasonable price (as opposed to some of the rated and cryo treated tube costs, so coming to an agreement is important, but how much effort is it worth...
Happy Listening
They measure emission, or on better testers they measure trans conductance.
A tube can test excellent on a tester, but may be too noisy to be usable in a specific application, especially a high-gain circuit like a phono preamp..
This one does.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
This particular tester has a "noise test". User is instructed to connect the two "noise" jacks to the antenna input of an AM radio. Tube is then set up and at some points in the test sequence you listen for noise on the radio either as the tube sits or by "flicking" it. Don't think this is up to audiophile standards but . . .
h
I don't own a TV-7, so I never noticed that feature. Like you say, it might only detect tubes that are so noisy, it would be the result of a broken internal support or internal arcing. An AM radio isn't going to provide a noise floor low enough to compare small signal tubes for hi-fi characteristics.
The TV7 is a military device designed for rough field service, is waterproof when lid is closed and has super rugged construction. Interestingly, there's a note somewhere in the operator or service manual that states something to the effect that despite tester results, the only real test of functionality is whether or not the tube performs properly in a circuit. IOW, a diagnostic tool but not the final word on tube condition.
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