[W9TR]

Here’s what you do. Once you’ve taken the amp out of the sub enclosure, measure the size of the caps you are replacing. Diameter is usually the limiting factor for radial leaded caps.

Then find a replacement cap that is the same diameter with the same capacitance rating and the highest working voltage and temperature rating you can find. If you have a choice, go for the longer base life part as well. A base life of 2000 to 8000 hours is a good target. 1000 hrs is low.

The reason you select parts this way is that voltage stress and temperature stress are the two things that kill electrolytic caps. It’s not linear either.

Doubling the voltage spec will increase life 2.65 times.

Increasing the temp specification is an even bigger life accelerator. Going from an 85 C cap to a 105 C cap when the cap itself is at 50 C will increase the life 4 times.

These effects are multiplicative. So all other things being equal using a 105 degree C cap with twice the voltage rating of the original will increase the life 10.6 times!

I have simplified the math behind these assumptions and can point you to more info if you’d like. I used The ATT Reliability Handbook and MIL HDBK 217 to make these rough calcs.

Tom