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
About a hundred years.
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?
I have no experience meeting that description, but FWIW I have many tubes in my antique radio collection from as far back as 1922, manufactured when tube technology was in its infancy, which work perfectly fine. And which in most cases were probably sitting unused for many decades during the intervening 90 or so years.

Regards,
-- Al
Al, 90 year old tubes! They predate Schubert. :)
I'm pretty sure they actually don't predate Schubert.
Almost forgot, I have '52 Sylvania 6SN7GTs and '42 Tung Sol 5U4G rectifier tubes that sound incredible. '42 tube would be 72 years old if my math is correct.
They'll definitely outlive us.
Tubes and wine are the only two things that get better with age, right? :^)
I heard some Navy tubes from 20's once, unreal good.
I currently use Western Electric 348, 349, 310 and 311 tubes. I think they are all over 65 years old. The only current production tubes that I have are EML 2a3 tubes.

Any modern tube bought now should easily outlive the purchaser, and perhaps, the purchaser's progeny.
I haven't used any 5-8 year old 21st century tubes, but I believe you would be safe buying a set of spares and keeping them in storage for a few years.
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,
Just like milk- look for the expiration date on the carton
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!
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.
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!!
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.
I've bought almost a hundred tubes, off eBay(some from
Germany, Australia, Argentina), in the past 9 years,
searching for the most accurate sounding/best sound stage
combination of phase splitter & driver, for my Cary
monoblocks and the output stage of a BAT VK-D5. All
purchased have been 6SN7GT variants, from
the 40's(ie: TungSol round plates, Sylvania 6SN7W tall/metal
base, Ken-Rad CKR, Sylvania VT-231 bottom getter and so on)
with the exception of a few Siemens CCa grey shields, from
the early 60's, for the CDP. I've found that if one
communicates with the seller and knows what to ask; it's
easy to tell if they know what they're doing. Everything
purchased as, "NOS" tested above, "new"
and those that I kept have given me many hours of musical
enjoyment, proving reliable(long term). The CCa's have
been going strong, for over 6 years, in the CDP. I've also
got a collection of tested back up tubes, for when the ones
in use are expended(the inevitable). My output tubes are
GE 6550As, from the early 70's(purchased NOS/not on eBay).
There's nothing to
dry up, wear or leak out of a vacuum tube, that's stored on
a shelf, outside of the possible entrance of air. If it
tests,
"GOOD" and not gassy, there's no reason it can't
perform as long, or longer, than a new production tube.
Like everything else: CAVEAT EMPTOR
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.
when it rolls off the shelf, the life's over.
Czarivey,

So sadly true. When I got my current phonostage, a friend gave me pairs of 5751s, Telefunken ECC83s, and Amperex Bugle Boy 12ax7s to try out in place of the RCA blackplates that came with the phonostage. I had the tubes in a small box on a shelf. I accidentally knocked the box off the shelf. Although the floor is carpeted some tubes banged against each other and cracked. As it turned out it was one of each type that was destroyed so I had no matching tubes.

In the end, I settled on Telefunken ECC 803S'. I actually found a truly NOS pair that were still in their aging boxes.
Schubert died years ago.

So did the composer.
150 years.
"does anyone know how long a vacuum tube will last just sitting on a shelf unused?"

Until they fall off the shelf and break!