Too much Rail Capacitance?

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john65b

john65b

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Joined 2005
#1
Currently building my UCD400AD Amp - hopefully the last main amp for main use for the next 10 years - and have a Power Supply Cap question...

Is there a real problem with 56000 uF/Rail for Power Supply Caps for this Amp? I read some like many individual Caps in parallel and some like one big one/rail....is there really a difference?

I just bought two of these United Chemi-Con 56000 uF, 63VDC, +95C cheap and was planning on using it bypassed with a 1uf cap...should be about +/-56V on the rails to the amp. Are these decent supply caps?

I also have a few Nichicon LQ 10000uf 63V Caps I can use, but only have 4 of them left, tho...

Torroid is an Antec 750VA 40V Dual Secondaries.

Any comments?
 
#2
I'm probably away from the crowd on this one, but FWIW you can probably get lower ESR by paralleling several smaller caps. I don't know if it matters or not. As for bypassing big electrolytics, I've never heard an explanation that holds water. The small caps can kill RF from the rectifier bridge, but to be effective that should be done right at the rectifiers, not many inches away at the filters. They can also provide some HF bypassing for the circuitry, but to be effective that should be done right at the circuitry, not on the other side of the wire inductance at the filters. OTOH, it shouldn't hurt anything if you do bypass the filters, and an awful lot of people recommend it. A class D amp can make some pretty serious demands on the supply, so more attention than usual to lead lengths, ESR and ringing is certainly warranted.
 
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