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Electrolytic filter caps : Pre - installation longevity ?


One year and then they are unsaleable.Many old ones are still useable as long as you re-form them with a variac,but it's best to get new stock and not worry about that.
So if you see NOS filter caps on E-Bay,don't buy them unless you know how to re-form them or like swapping them in and out of a complete amp build.
We can't see inside filter caps to see if the electrolytic compound is dried out,so why take a chance?
Now I may be wrong here,so those who truly know please pipe in.

John Phillips

I wouldn't install one over ten years old at all, and not over five years old in a critical application. I don't think I'd draw a line as soon as a year - amps which haven't been turned on for a year or more are usually perfectly OK.

Basically 'NOS filter caps' are an oxymoron though...


Not in the context of guitar amps but in other applications requireing electrolytic caps I routinly use stock that is over a year old. Like John said I wouldn't use something 10 and maybe even 5 but 1 or 2 years has never been a problem.


Senior Member
I have read somewhere that the shelf life of new production electrolytics is 5 years. After 5 years, reforming is suggested.


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