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Tube Life

I’m using a phono pre-amp with a pair of telefunken 12AX7 and one 12AT7. I purchased these tubes several years ago and they were rated at about 50% life. Are tube noise and tube rush the only reasons to change out tubes? Everything is silent and yet I can’t help but think that several years of use should indicate some sort of wear. Any experience or suggestions will be appreciated.
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uru975
684 posts
 
When Thor Audio was around I talked with Paul Marks, its founder. His view was leave it on 24/7 and just change the tubes each year. So that would be about 9000 hours of use. Make a guess at how much you have used them and that's a very ballpark estimate of whether to get new tubes. Sound is another good guide.
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thorman
1,262 posts
 
Do it the right way,,When in doubt,buy another set and have them on hand..If anything changes ( in sound ) dump the old set for the new...Always try to stay one step ahead of trouble.......
jallen
502 posts
 
I have a friend using 6sn7tubes in the amp input and they are 15 years old. Working well, no noise or problems. Use until noise is an issue. Life ends with noise for me. Jallen
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tomcy6
2,532 posts
 
Telefunkens are known for their durability so they may be chuggin' along just fine. Or there may be a decrease in sound quality that you haven't noticed because it occurred gradually in imperceptible increments.

If you plan on keeping the phono pre you will eventually need new tubes so you might as well get them while you've got time to look for a deal. When you get the new ones plug them in and see if they sound better. When the new ones sound better, it's time to retire the old ones for emergency duty only.
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