2. amps-preamps
  3. 1325539436

six year old 6sn7's, pushing my luck?

I retubed my Cary SLP-05 with Pope tubes about 5 years ago. I leave the preamp on pretty much all the time except when I go on vacation. That comes to about....45,000 hours. The tubes are supposed to be good for 10,000.

And...I've experienced no noticeable degradation in the sound. I heard a clicking sound once when I turned the system on after a week's time off, but I jiggled the offending tube and the sound stopped.

I've experienced tube failure and noise and rush in other systems, but this one seems to be the Energizer Bunny of tubesets.

I wish those Pope tubes were still available for a reasonable price, but Upscale now wants $275 per tube, and I need 6 -- I just cant justify 1650 to retube the preamp, but for now maybe I don't need to.

Any thoughts on this? Have you had tubes that lasted like this? Could they be degrading so slowly that I don't notice? Am I taking any chances with my equipment?

Thanks much and happy new year!

Rich
rbirke
elizabeth
6,726 posts
 
Agree preamp tubes (almost) always go out with a wimper.
So yu can use them until they actually start to fail.
Some designs are easy on tubes, some really hard.
Seems your preamp is just kind to tubes. So I would not worry and just keep using them until you feel you are missing something, or they get noisey.
Chasing after slightly better sound wwith new tubes does not seem to be your thing. So I would avoid the suggestion you 'might' get better sound with new tubes.
Why worry, be happy!
(For amps the story would be different, but preamp.. no problem)
griffithds
851 posts
 
You should buy yourself a backup set of new tubes. The inexpensive EH brand would do just for situations like this one. Rotate the new EH tubes into the preamp and listen. If these generic/boring sounding tubes sound better than your current tubes, then you will know it's time to replace. Tubes as you have stated, do gradually wear out at such a slow rate that it is quite possible for it to happen without you noticing it.
honest1
572 posts
 
My first thought wsa why not shut it off except when listening, but then I thought maybe leaving them on is helping them survive. Everything I cna remember reading says to shut tube gear down when not using, but leave it on if it will be unused for only a short time. I remember - vaguely - something about the heating and cooling cycles not being good for tubes, maybe the expansions and contractions of the parts damages the coatings).
brownsfan
1,238 posts
 
The sophia tubes run $100 each and are pretty good. You might want to think about them. I also agree it makes sense to keep a cheap pair of current production tubes around.
dtc's avatar
dtc
1,024 posts
 
If you are using single ended inputs, you only need to change the 4 tubes on the left. The 2 on the right of the main group (not the headphone ones) are used as buffers for the balanced inputs. In a recent newsletter, Cary had a picture of a modified SLP-05 they had at RMAF with 4 Black Treasures and 2 more normal tubes. People like the Black Treasures but they do not fit the holes in the top plate - you need to enlarge the holes. New Psvane tubes (CV181-T) are based on the old Treasures and are starting to become available from Grant Fidelity, at half the price of the Pope's. I thought about the Pope's but Upscale says they only sell them to people you got their pre from them. But, it sounds like your Pope's may last forever. Good luck!
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