Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Rickinbeachcrest on September 17, 2021, 01:32:12 pm
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I've been looking through ebay and noticed a lot of used vintage tubes that test good.
Any thoughts on this?
Thanks.
Rick
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buyer beware
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definitely buyer beware, but can be a good way to scoop up some old tubes. better when the listing includes the tube tester they've used along with readings, but who knows if it's calibrated correctly. best tube tester (besides testing for shorts) is an amp
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They may test good but make noise etc. I buy cheap only and run them all through a working amp and write down a signifcant value eg cathode voltage to be able to compare them and also mark the noisy ones if they are preamp pentodes. This may seem impractical but i dont want to have an amp with expensive tubes i cant replace anyway.
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When you need 7189As there doesn't seem to be much choice?
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NOS 7189A tubes are still available from reputable tube dealers. Not cheap, but available.
https://www.kcanostubes.com/catalog/31 (https://www.kcanostubes.com/catalog/31)
The 6p14p-ev tube is a viable substitute.
https://frank.pocnet.net/sheets/113/6/6P14P.pdf (https://frank.pocnet.net/sheets/113/6/6P14P.pdf)
NOS 6p14p-ev tubes are still available, but prices are rising.
New Sensor continues to make this tube and markets it as the Sovtek EL84M and/or the Tung-Sol 7189.
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Right now I have about 16 of them. I have stocked up. Didn't know they were available new.
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I’ve had decent luck with used vintage tubes on eBay, trusting the spoken condition is another matter. So, l only buy when in lots and cheap. I test them in an amp, usually with fixed bias so l can at least read the bias voltage: if this voltage is consistent, the tubes usually sound good. I’ll match power tubes this way on bias current, works well for me.