Indicators of worn/bad capacitors?

confirmation of problems, and/or confidence in your system, primarily your speakers placed thusly in your room, can be achieved by two inexpensive tools,

sound pressure meter, tripod mount, set at ear level listening position

test cd with specific frequency bands to compare band to band, I acquired several test/demo lps and cds, I find this one, tracks 9-38 easiest and informative

Thanks for the insights! I'll take a look at the capacitors today and I'll try leaving the system on for several hours before listening. I haven't listened to it in >6 weeks so maybe that's part of the problem.

As for other listeners' perspectives, that's just my wife. She thinks the entire enterprise is "nuts" and says, "It sounds fine. Stop worrying about it."

You can get a cap checker quite reasonably on Amazon. Just be sure to discharge the cap manually with a shunt before you use it, or let the amp sit for quite a while (so the caps discharge that way).  I forgot about that once & fried my first cap checker.  (And I did have a shunt handy . . . I just forgot.)

immatthew,

That's a good plan! I've never heard of that device before. Hopefully, it's designed for someone who knows nothing whatsoever about electronics (me).

Thanks,

Keith

visual clues include swelling, discharge of any substance at the base of the capacitor, heat discolouration and general old age (although old caps can still function OK).

This is only if the capacitor is heating up. If the cap isn't heating about all that might be happening is the total capacitance is lower than expected. That can in turn increase the IMD of the amplifier (which tends to manifest as harshness and possibly also brightness).

You can get a cap checker quite reasonably on Amazon.

You can, but it won't tell you if the cap is failing, unless the value reads significantly off. I've measured plenty of bad caps that the tester said were OK.

If the amplifier is really 35 years old the filter caps probably are suspect. We're talking about the 1980s still- anything made in the 1980s has suspect filter capacitors, and the fact that the amp sat around for a long time doesn't help- that might actually be worse for caps than keeping them charged (they have that in common with batteries; electrolyic capacitors have a chemical element that film caps do not).