2. amps-preamps
  3. 129043-3520

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
mechans
2,999 posts
 

I still think it prudent to get some new output tubes.  That family of tubes run hard, and even with limited use, it's time. 

he tap test, no matter how widely used , even by some dealers, isn't a good test. Even the gentle focused tap test isn't what I would use.  A microphinic tube with make bad sounds, when moved and more importantly,  when played- they produce  a feedback sound and ring and they also transmit any physical perturbation. 

As for figuring out which of multiple potential tubes go I would be inclined to remove the suspect and roll in another tube.  That does require a set of "good" back up tubes.

  I was going to say remove and replace but I didn't want to get political.

wolf_garcia
4,650 posts
 
To deny yourself the experience of the "High Fun to Expense Ratio" of tube rolling seems to ignore the fact that life is too short to not at least try to enjoy new things. 
dragunski OP
110 posts
 
I tend to "roll" signal tubes and preamp tubes more than the power tubes. This has made larger differences in my mind. But once I've got it sounding good, across different sources, I don’t want to mess with it.

In any case, just shifting the tubes around and cleaning connectors seems to have solved the problem. But I'm going to find those damn Philips tubes in the basement. It's bugging the hell out of me.
mechans
2,999 posts
 
You really should get those Mullards or whatever Philips brand you have hidden in your basement.  The Mullards are really good sounding if you like a warmish signature.   In addition  true NOS command serious money these days.
dragunski OP
110 posts
 
They are Philips brand tubes. The seller told me they were made by Mullard, but he was Chinese and I may have misunderstood. The amps were recapped in the 80s and may need it again, but for now, they seem to be working well. There's a little hissing when they power up, but it goes away pretty quick.

Yes, tomorrow I will dig around again in the basement. I'll be mad if I don't have them anymore. I found all sorts of cool stuff down there including reel and Elcaset tapes, so I think I'm getting close.

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