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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
lewm
13,400 posts
 
Re the SP14: What I thought based on memory, but I was too lazy to look it up. The SP14 did not use 12AX7s at all, so the story if not relevant.
jyprez's avatar
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.
dhcod
710 posts
 
I've had Tele 12ax7s in a Rogue Atlas for 4 years and they still test new. Rogue is very easy on small tubes.
andyprice44 OP
133 posts
 
that is good to know about the rogue atlas. I hope I can get at least 5 years of service out of my tubes as they are a bit pricey.
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