Indicators of worn/bad capacitors?

Final follow-up:

I looked at the capacitors and everything seems pristine. Also, I've left the amplifier idling for a few days and now...all sounds fine! No more harshness/brassiness/glare. I'll just leave it on from now on.

Thanks to all for your help,

Keith

Update:

I've let the amplifier "idle" for a day or so and listened again this evening: much better. I also called a local electronics shop here in Portland that does exclusively stereo servicing and explained the problem. The owner told me bad capacitors make other noises, but not harsh sounding music (as others here on the Forum also wrote). I've set aside some time tomorrow to take a look inside, just to be sure everything looks virginal.

Thanks to all,

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).

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

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.)

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."

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

over all the years, SS or Tubes (already broken in): on, 20 minutes, listen, off.

nothing changed, no obvious noise problems when on/no content playing, I suspect visual inspection (above and below) will reveal nothing.

Is it possible something subtle is going on with your hearing? Anyone else familiar with your system agree harsh/bright?

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).

Thanks to all of you for your helpful comments! I'll try leaving it running for a week and re-assess the situation.

Keith

You capacitors are no culprit then.

I would recommend if you listen to SS amp weekends only to keep it on all weekend. Wait at least 20 min before listening after turning on.

Maybe I should just have them replaced. Is that an expensive procedure?

replace caps based on type and age.  

Caps can dry out but still work on a 35 year old amp even with little use 

Thanks for the replies!

1) No hum or other noise that I can detect but I haven't removed the top of the amp to look (but, following your advice, I will do that tomorrow) and,

2) I leave the system off almost all the time. I only listen on weekends. Would leaving the amp running constantly help?

Keith

Did you leave it off all weekend and then come back?

From your words, your capacitors are most-likely okay.

Caps going bad in SS amp will hum and possibly pick-up RFI noise almost just like tubes.

The other way is to look at those if they show any signs of heat impact, discoloration or deterioration of print. Electrolytic DC caps usually can show that they're getting little 'fat', showing some loss of liquid around it.