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Tube Life Artifacts

I've been using the same tubes for almost 12 years. They are RCA EL84s (6bq5) in 1959 Leak TL12 plus monoblocks. Recently, I have noticed that one channel seems to be "deeper" in soundstage, almost like there was more reverb on that channel. It's a mild difference, more noticeable on some recordings than others. This difference is consistent with both vinyl and CD, and switched sides when I switched the speaker connections.

Is this evidence of tube deterioration? I have a set of unused Philips tubes somewhere in the basement (made by Mullard, I believe) and I'm about to switch them. If I can find them...
dragunski
yogiboy's avatar
yogiboy
5,701 posts
 
A microphonic tube will have the sound you describe1
rcprince
3,073 posts
 
I was going to suggest the microphonics possibility as well.  I think you should switch tubes between the amps to determine which tube might be the culprit.  After 12 years, though, it might be time to try new tubes to see if you've lost some frequency extension and dynamics.  You may be pleasantly surprised.
dragunski OP
113 posts
 
Thanks. If I could find my spares,  I'd swap them out now. I thought they were in a box marked "Dynaco", but all that was in there was EL34s.

The last time I moved, I packed them up very carefully.  Too carefully, it seems. Now I have about 30 boxes to go through.

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