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Tube Test Results

I've read descriptions of tubes for sale here claiming that claim the tubes for sale "Good" or "Excellent" on their teting machines. What does this mean?

If a tube is not "Excellent" does that mean that their is not as much life left but, sound quality is not affected or, tube life is deteriorating and sound is too.

I guess my ultimate question is, do tubes burn out like a light bulb - running strong until the filament burns up or, do they die like a battery - less and less energy over time?

Talking about specifically 6SN7GTs as an example - if that matters.

thanx
pawlowski6132

Showing 2 responses by gunbei

gunbei
2,327 posts
 
Yeah, your assumptions are more or less correct. Aside from identifying shorts, each tube tester has its own standards for what is passable and excellent.

Tubes do burn out in varying degrees depending on the tube type and how it's being utilized. I have a DAC that uses two 6922s and I'd leave that DAC on 24/7 for three or four years with very little noticeable degredation of the tubes.

My preamp goes through 6SN7s much quicker. It may have to do with the ones I use all being WWII era tubes or maybe it could just be the way they're being employed in the design of the preamp. But it gets expensive.

Power tubes can be even more costly.
gunbei
2,327 posts
 
LOL @ Pawlowski6132!

My experience with 6SN7s dying is similar to Jburidan's except it seems to happen in one channel before the other. Also, if one channel starts crackling whenever you adjust the volume that could also be a sign of a tube going bad.

I really love the way 6SN7s sound, but in my set ups they seem to go bad much quicker than 6922s. It could also be the applications I had them in.
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