Question about adding caps to an amp

mattjk · 10th December 2004, 04:34 AM

I have a B&K ST202+ that I would like to add a pair of filter caps to.

Would it be OK to add 2 different values?

The stock caps are 14.5K and the ones I would like to add are 100K. I tested it tonight and I was very please with the sonic results. Should I completely remove the old caps?

Also, the new caps are 63v, and the rails measure 64v. Am I asking for trouble, or would this be OK?

Thanks,
Matt

AndrewT · 10th December 2004, 06:58 AM

Hi,
Personally I would use 75v caps here.
Your dc voltage also has some ripple, so peak volts will be higher than the 64v you've just measured. What happens when the mains voltage goes up? Leakage on an electrolytic goes up as voltage rises towards rated volts.
Based on those 3 criteria (& some others) some designers will use even higher rated caps.
The life of the caps is finite and running them at or over their rated voltage may seriously reduce their lifetime.
regards Andrew T.

anatech · 11th December 2004, 12:26 AM

Hi Matt,
I agree with everything Andrew has mentioned. I would add that much higher capacitance is not good. Why not just replace the old caps with new (not surplus) caps around the same value? Your rectifiers are not rated for the high peak current that the units you have will cause.
-Chris

renehuot70 · 11th December 2004, 05:32 AM

Try to install many small caps.

I own a HK citation 16 . It have 4 can 10000UF.

I put 1000uf, 470uf, 47 uf in paralel with those big 10000 uf.

WOWWW what a result!!!! hearing is beliving

A friend of mine explain to me that larger can are good for base but they are slower for mid or high.....The smaller cap are much faster and they "fine tune" the filtration.

I know it is PFM but try it...it cost only 10$ for 12 caps for my DIY mod

happy x-mas
coyote

10th December 2004, 04:34 AM	#1
mattjk diyAudio Member Join Date: Aug 2004 Location: Huntington Beach, Ca	Question about adding caps to an amp I have a B&K ST202+ that I would like to add a pair of filter caps to. Would it be OK to add 2 different values? The stock caps are 14.5K and the ones I would like to add are 100K. I tested it tonight and I was very please with the sonic results. Should I completely remove the old caps? Also, the new caps are 63v, and the rails measure 64v. Am I asking for trouble, or would this be OK? Thanks, Matt

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10th December 2004, 06:58 AM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, Personally I would use 75v caps here. Your dc voltage also has some ripple, so peak volts will be higher than the 64v you've just measured. What happens when the mains voltage goes up? Leakage on an electrolytic goes up as voltage rises towards rated volts. Based on those 3 criteria (& some others) some designers will use even higher rated caps. The life of the caps is finite and running them at or over their rated voltage may seriously reduce their lifetime. regards Andrew T.

11th December 2004, 12:26 AM	#3
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Matt, I agree with everything Andrew has mentioned. I would add that much higher capacitance is not good. Why not just replace the old caps with new (not surplus) caps around the same value? Your rectifiers are not rated for the high peak current that the units you have will cause. -Chris

11th December 2004, 05:32 AM	#4
renehuot70 diyAudio Member Join Date: Nov 2002 Location: canada	Try to install many small caps. I own a HK citation 16 . It have 4 can 10000UF. I put 1000uf, 470uf, 47 uf in paralel with those big 10000 uf. WOWWW what a result!!!! hearing is beliving A friend of mine explain to me that larger can are good for base but they are slower for mid or high.....The smaller cap are much faster and they "fine tune" the filtration. I know it is PFM but try it...it cost only 10$ for 12 caps for my DIY mod happy x-mas coyote