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Old 15th November 2004, 01:56 AM   #1
mattjk is offline mattjk  United States
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Default Is there much sound difference in using multiple small caps

as opposed to a single large cap?

I want to use one 82000uf cap per channel. My case it too small to fit a pair, but I can stuff 16 - 10000uf caps, or 8 - 20000uf caps into the case.
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Old 15th November 2004, 02:11 AM   #2
quasi is offline quasi  Australia
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The theory is that with multiple capacitors you reduce the overall inductance which is a bad characteristic of all capacitors.

The lower the inductance the better because this reduces the overal bypass impedance to gnd (or whatever).

If the parallel capacitors are of a good quality then yes you will get better filtering of the power supply this way. In my amps I generally try to use multiples rather than one big fat one.

Whether you would hear it in your setup is a suck & see exercise.

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Old 15th November 2004, 02:34 AM   #3
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I've read in many places that it can make a difference, but it depends on a few factors. I've never really explored this option, so I don't know if my impressions below are correct. Forgive me if I'm wrong.

1. The paralleled ESR of the multiple caps needs to be lower than the ESR of a single larger cap. When the rectifiers are not charging the caps, any current the amplifier draws from the PSU will discharge the caps through the ESR. All things equal, a lower ESR will mean more maximum current available to the amplifier.

2. Watch out for the ripple current rating of smaller caps. You could use simulation to figure out how much ripple current is present in the caps. The Duncan PSU Designer is an excellent tool.

3. Smaller caps may have lower impedance at higher frequencies. Unfortunately manufacturers don't generally publish impedance vs. frequeny plots of capacitors, so I don't know if this is really true.

EDIT: Oh yeah, I forgot about the inductance Paralleling would definitely lower that and make #3 true.
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Old 15th November 2004, 03:21 PM   #4
AndrewT is offline AndrewT  Scotland
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I have just opened up a commercial power amp and inside were 32 caps forming +/-34,000uF at +/-50v
regards Andrew T.
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Old 16th November 2004, 04:49 AM   #5
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Default I founded that when you have less than 5000uF for each ampere...

The bass turns strange.

Calculate the peak amperes and multiply by 5.000uf , this is some day by day result, not a calculated value.

Also i could feel, someday, that putting parallell diodes in the bridge rectifier unit, the bass also "seems" to be more strong.... but those things do not make any sense to me...only made sense to my ears long time ago.


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