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vacuum tube shelf life

does anyone know how long a vacuum tube will last just sitting on a shelf unused?

the recent trouble in ukraine along with the threats of embargoes and sanctions against russia had me questioning the reliability of the supply of freshly made russian vacuum tubes. it got me wondering if i should get an extra set.

however, the tubes in my preamp are pretty new and it might be some time before they need to be changed. so any new tubes i get now are likely to sit unused for several years, possibly as much as a decade.

so will the tubes still be good when i finally try using them?

i understand that there are a lot of NOS tubes being used, most of which are old, as in 50 or 60 years old. on the other hand, the NOS tubes that are in use are survivors and i have no idea of the failure rate; how many NOS tubes have to be discarded simply because they went bad in their boxes while sitting unused. plus, from what i can tell, new tubes don't seem to be made to as high a standard as tubes used to be in their heyday in the 1950s and '60s.

what have been your experiences using tubes made in the 21st century that have been sitting on a shelf for, say five to eight years?
the_rook
charles1dad's avatar
charles1dad
10,249 posts
 
Rook,
You're getting good reassurances here and I agree with them. Tubes last a very long time and they provide beautiful sound. Just continue to enjoy them.
Charles,
zavato's avatar
zavato
1,397 posts
 
Just like milk- look for the expiration date on the carton
ait
480 posts
 
My preamp uses CX-326 tubes made alnost 90 years ago. They sound incredibly good.

As for the Russian tubes, I recently bought 50 of the 6E5P that I use as driver tubes in my 833C amps. I have no worries about them dying before me!
swampwalker's avatar
swampwalker
5,138 posts
 
how many NOS tubes have to be discarded simply because they went bad in their boxes while sitting unused.
That's an easy one to answer. Based on my experience, just count the number of "NOS" tubes added to ebay each day and multiply by the number of days since ebay was first launched. That'll tell you how many NOS tubes have gone bad sitting on the shelf, because I have NEVER, EVER, EVER bought an NOS tube from an ebay seller that measured close to NOS. In fact, less than half actually measured "good" on a calibrated Hickock Tester.
mabonn
181 posts
 
I have a lightly used ARC SP3 which I bought in 1975. It still has the same tubes I bought it with, and it works fine. The preamp sat unused for about 15 years, then I sent it back to ARC for the 3C upgrade in 2003. ARC tested the tubes and said they were still good. I have been using it lightly since 2003 and it still works fine and sounds great. Original tubes!!
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