wrote:
In high end speaker they are not always electolytics. They could be but
there are some different types. You can look them over at Simplyspeakers
and a few other places.

Anything other that a lytic of some of those ratings will be quite
expensive, so unless you got really good ears forget it. One technique is
to put a smaller cap like a poly or something across it, but then you
have to recalculate the value. Easy to do, just subtract what you add.

The non electrolytics have more lifetime. In a system, retrofitting with
"better caps" can result in improper repsponse from what a speaker was
voiced at. Add resistance and possibly loss, and you have an electrolytic.
As far as tolerance, they are pretty accurate, and often tested before
installation. Normal electrolytics have given tolerances and can vary with
temperature, including varying ESR.

Greg