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Lifespan of NOS telefunken 12AX7?

Hello,
I just purchased a quad of NOS telefunken smoothplate 12AX7's from brent jesse. I have seen some 12AX7 tubes rated for up to 10,000 hours. These have been some medical grade tubes such as the mullard 10M series. I have some mullard longplate 12AX7's and 12AU7's that I have been using on a regular basis for the past two years. I would say they are getting close to 1200 hours on them. They are still going strong and sound good. I was just wondering what the general lifespan of a standard telefunken 12AX7 tube was. I am using them in a rogue ares phono stage. How many hours would you guess they should last. I understand there is no set number of hours but, I am interested in knowing a tubes useful lifespan. I tried to find some info on google but, I couldn't really find anything that stated a lifespan of standard telefunken tubes. Thanks in advance.

Andy
andyprice44

Showing 1 response by jyprez

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jyprez
241 posts
 
10,000 hours is not very long if you have to leave your phono stage on 24 hours a day but only listen for one or two.

I have used Telefunkens and Amperex Bugle Boys from Vintage Tube Services for many years in my LAMM LL2 pre amp (which uses both 12AX7's and 6DJ8's) and find that I can get 3 to 6 years at 2 hours per night before the sound deteriorates or goes microphonic to the point I want to change - depends on your ears and mine are not the best. Phono stages may require more frequent change but mine is SS.
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