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Speaker Re-cap. How do you know when?

Howdy. Looking for input on speaker capacitors & their life span. I have a set of Infinity Renaissance 90's and the bass seems to be thinner than it used to. Thinner meaning not as strong, feel it in your chest type bass. The speakers go down to 27hz, so I know form the specs and experience that it can happen. Reason I am asking about the capacitor, is "back in the 70's", I had a pair of Pioneer speakers that occasionally would literally blow the insides out of a cap. I'd go to Speaker City grab a new one & solder it in till she blew again.
Question; Is there a chance the caps are old & hammered or am I searching the wrong area? What have you folks experienced? Are there even caps in the woofer cross-over’s?
Speakers are powered by Krell KCT pre & Krell FPB300cx.
PS - The surrounds look like new.
Thanks for any input and advice.
-John
jsd52756
casouza
239 posts
 
Howdy
You may want to open the speakers and find the largest capacitors in the crossovers, then verify if those caps are in paralell with the woofer(s).
Assuming that Infinity used a second or higher-order crossover, you will find an inductor in series with the woofer(s), then a cap in paralell. If that cap is leaky, some of the symptoms could be weak bass or too much midrange, which sounds like weak bass.
To avoid frequent replacements, buy caps rated for at least 100 volts. Nonpolar caps are better for crossover duty than regular, polar caps.
Good luck
stanwal's avatar
stanwal
3,147 posts
 
Getting better caps can also improve the sound. Silver wire or higher quality copper can also be a big improvement.
face
516 posts
 
Make sure there are no air leaks. Make sure all drivers, binding post, etc...are all secure.

Electrolytic caps usually last about 20 years, so it's probably time for a recap soon anyway. If possible, use all film caps. I believe those speakers are somewhat forward already, so I would avoid Solen caps.
jsd52756 OP
432 posts
 
I found a cross over scematic last night on the net. I'll do some research on the matter. I like the note about air leaks. While all looks A-OK, I'll double check. I am not that much of an elctrician to know how to check the cross overs with an ohm meter, which is how I suppose it should be done. I see Humble Homemade HIfi has done some capacitor comparison which looks cool. Anyone know of a good reputable shop I could send the cross overs to to have them checked & possibley tuned up? Probably would'nt hurt.
Thanks again, John
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