Cap life span?

Rodman:

Yes, that is why tantalums are called "solid", although some military versions actually have a liquid electrolyte in them (VERY EXPENSIVE). The solid versions use MnO2 electrolytes that are produced by evaporating the salt solutions during manufacture.

They are not designed for power supply main filtering, only bypassing and for timing circuitry. They have very low leakage currents, about 1/10 of the leakage through Al electrolytics. They range from about 0.1 to 200-300 mFd. Outside this range they are not applicable. The larger capacitance versions can be very expensive.

One audio application I have used them for is the timing circuits in my Parasound JC-1. Replaced the Al electrolytics that Parasound used stock with tantalums and now my turn on time delays (there are three of them, sequential) are rock solid.

I would not recommend them for audio coupling due to their non-linear dissapation factors and dielectric performance. But they last forever.

I like to rotate mine every six to twelve months. You know, so they get even wear. It sucks when you open up a case only to find one cap has all it's tread worn off and another looks brand new.

Hmmmm.... I'm thinking if two different things.

But seriously, this is a subject near and dear to my heart. Not only am I a lover of older SS amps (Citation 7.1/5.1, Acurus A250, Haflers, etc) but I also love to fiddle with older computers. I have a collection of motherboards from that wonderful period of the mid to late 90s when there was a batch of caps that had a stunningly high failure rate. On pretty much every one of those babies you can see the cap bubble. Yep, makes me want to get the ole soldering gun out right now.

Anyway, I've been trying to decide just when some of my amps need to be serviced. It is an expensive proposition, especially when you include shipping both ways. I'm hoping the Citations can run, say, another 30-50 years! (yea, I'm hoping that -I- can run another 30-50 years). ;)

Years ago I had a PS Audio 200C amp and it wasnt sounding right. Called their tech and he told me that the life of the caps was about 15 to 20 years, depending on use.

A simple answer is are they old when you measure them, or when you listen to them? Odds are you can measure changes before the ones that you can hear. I have a 32 year old APT 1 amplifier that sound good but the caps would invaribly test poorly by now, though.

And to that end, heat and years do add up. A hot class A amp will more than likely fall offs it performance curve before a cool running class D amplifier.

I agree with the 20 year "servicable" life. Anything after that is gravy with electrolytic caps. But MANY a component goes way past that. Capacitors are like valve tubes, same type tubes can go in a year, some decades. Same tube, different life. On solid state change years to decades and decades to 20 years.