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?

Showing 2 responses by swampwalker

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.
If one buys tubes that do not measure in the, "NEW" range, on a calibrated tester, but were described as, "NOS," either the seller didn't know what they were selling, or they lied.
Exactly. Either way they were not NOS. My life is far too busy to hassle w re-packing, paying for shipping, and HOPING to get a refund. I buy tubes from dealers w established reps on A'gon or their own web presence and a long history of honesty. I'm glad you've had good luck on ebay, Rodman. I was just venting (pun intended). You are of course correct, as long as the vacuum is maintained, and there are no shorts, unused tubes don't deteriorate over time. IOW, if they are good, they will stay good, assuming that they do not get physically damaged. So if you stock up on new tubes now, and leave them in a safe place, they should be fine when you use them 2, 5, 10, or 50 years from now.