About Storing Tube Amps/Tube gear

[Dan Lawrence]

I have been told that it is detrimental to tube-based gear to put it in (climatized) storage for long periods of time, and the life of the amp is much better maintained by firing them up at least a few times a year.

I have eight (many vintage) tube amps and a few pieces of tube recording gear. I estimate I will have to store them for at least 2 years, if not longer.
I am trying to decide whether or not to sell them instead, but I don't really want to let go of them yet.

I'm just curious what tech/pros think about this subject, and if they think this info about not firing them up is correct. (I believe it had something to do with the caps picking up moisture, even in dry storage)

Thanks for your thoughts

Dan

[Leo_Gnardo]

I'm just curious what tech/pros think about this subject, and if they think this info about not firing them up is correct. (I believe it had something to do with the caps picking up moisture, even in dry storage)

It has more to do with hi voltage electrolytic filter caps remaining uncharged for long periods. It is the hi voltage the "keeps them alive" so to speak*. The dielectric insulating layer in these is aluminum oxide, which forms on the surface of the aluminum foil conductors in the presence of an electric field - hi voltage to be precise. When I was but a youngster, an old geezer of a tech (I'm now his age) told me electrolytic caps would last just about forever if left constantly charged. Of course I thought he was full of beans but it turns out he was right. It's a good idea to fire up your amps once every month or two even of only for a couple of minutes.

Electrolytic caps also have a lifetime. I've had 'em go bad in as little as 18 years, also seen 60+ year old caps still functioning perfectly. Suffice it to say any amp past 20-30 years old is a candidate for new filter caps. The older they are the less likely they are to accept a couple years of being left uncharged. Before firing up your oldies-but-goodies make sure the proper fuse is in the fuseholder. If you want to be cautious you can slowly bring up the AC supply voltage of the amp with a Variac (think of it as a big volume control on the AC line) or use a "light bulb limiter" when initially powering up after long storage. I'll leave it to you to search "light bulb limiter" on this site - it's a well covered subject and will take you a couple bucks and at most an hour to assemble even if your fingers are frozen like mine are after shoveling snow today.

Non-electrolytic caps don't have this problem. Some amp manufacturers use film caps for hi voltage filtering, Carr f'rinstance. Carr's power supplies will probably last hundreds of years, not just decades, without needing maintenance.

Then, there's corrosion. Left unused, pots can get noisy, switches & jacks sometimes stop working the way you want. Often enough just exercising the pots switches & jacks will restore function. Might need a shot of spray if they don't come around quick. I like Caig F-5 for pots and D-5 for switches and jacks, followed by a shot of non-residue solvent spray. About this last sentence - I'm sure others will disagree and yet others agree - there's a lot of controversy over cleaning chemicals.

[Dan Lawrence]

Hey Leo -

I really appreciate that rundown. I know how finicky filter caps can be, just wasn't clear on that voltage storage issue. Sounds like the story of deep-cycle batteries. Your post will go in my tube-amp maintenance folder.

Cheers,

Dan

[km6xz]

I have some gear still in storage back in the US, in a fairly dry portion of the country where it seldom gets over 20% humidity in the summer and have noticed the pitting of metal surfaces I would normally associate with more moist and corrosive atmospheres. I have a classic Italian GT car in storage also which has fared better because I coated everything with a layer of oil or other atmosphere blocker. The last two times I went back to the US I did not even clean it up and drive it probably because I have gotten so used to public transportation that the craving to drive is waning. I brought a lot of test gear here over the last 10 years but still have nice pieces in storage so I sprayed the metal surfaces last time I was there with de-oxidizer and wrapped it all in plastic with no air paths.
Using the gear occasionally would be better, but I do not have that option. I gave away tons, literally...cars, a plane, test and recording equipment, (a Studer A800 24track, a Sony PCM 24 track, a large form Trident console, mics etc), a house, all the furniture in my 14 room house and vacation home, in the two weeks before I moved here, knowing that they should be used and would be a waste and waste away if not used. That was 11 years ago. If you are only storing for 2 years, I would suggest treating every surface, wrapping it air tight and store in a moderately cool temperature with low humidity and in only 2 years, you should not see any deterioration, even in filter caps.

[eschertron]

...or pick volunteers to your equipment in running condition while you're away! :hand:

[Leo_Gnardo]

I sprayed the metal surfaces last time I was there with de-oxidizer and wrapped it all in plastic with no air paths.

Good idea Stan. I'm curious & I'm sure others are too, what de-oxidizer do you recommend for this purpose? Thanx in advance!

[Chuck H]

olive oil

[Chuck H]

and in only 2 years, you should not see any deterioration, even in filter caps.

Agree! Filter caps of only a couple of years age will usually "re-form" on their own quite effectively with only a couple of years stagnation. Five years is death though!!! Thought I would mention that. Relaxed is fine, but don't get too relaxed. I've known older design caps to hold up well with five, or even ten years of no use. But newer design caps, while higher in performance and having better specs overall, don't seem to tolerate long periods of stagnation well.

For best results just blast away on your amps once a year. It's good for the soul too Put them through the paces to make sure the caps charge, discharge and pump a little. I've seen old design caps that got a few hours of use per month that were working fine after forty years!!! I would never count on that though. And newer design caps may not be up to it at all. Too soon to tell