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"Audio Grade" vs "General Purpose" Capacitors for POWER SUPPLY

post #1 of 13
2/27/11 at 3:06pm
Thread Starter 
Hi,

I'm building an LM3886 amp and for the power supply section, I need 2 10,000uF caps @ 63V. Snap in configuration is preferred.

For the main bulk capacitors on an amp's power supply, would it make any noticeable difference if I used cheaper $7 Nippon-Chemi-Con KMH capacitors vs using. $18 Nichicon KG "Audio grade" capacitors. In the signal path, and throughout the rest of the amp, I plan on using "audio grade" capacitors, but for the power supply, how much sonic difference would it make if I used general purpose caps?

Would I be defeating the whole point of using audio grade capacitors throughout the amp if I used standard grade caps on the power supply? Or not?

Thanks.
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post #2 of 13
2/27/11 at 3:37pm

I would not use "Audio Grade" caps in the power supply.

Power supply cap serve a different purpose.

One of the main specs to look at for power supply caps

is their "ripple current" spec. Caps meant for "power supply

use" are built differently from "general purpose caps" just

as "audio grade caps" are built differently from "general

purpose caps".

 

Hope that helps...

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post #3 of 13
2/27/11 at 3:41pm
Thread Starter 
Yep I understand you perfectly. I didn't even bother to look at ripple current ratings on the KGs. I bet they would be much lower even than your general purpose cap...

But perhaps not.

THanks.
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post #4 of 13
2/27/11 at 3:49pm

For "ripple current", the higher, the better.

It's a measure of how much current the cap can

supply to suppress power supply noise.

You will often see lower ESR along with higher

ripple current specs.

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post #5 of 13
2/27/11 at 4:31pm
Thread Starter 
I meant the KGs ripple would be lower than even standard grade since they are supposed to be for audio and not power supply. Sorry for my crappy wording.
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post #6 of 13
2/27/11 at 4:50pm
Quote:
Originally Posted by TheLaw View Post

I meant the KGs ripple would be lower than even standard grade since they are supposed to be for audio and not power supply. Sorry for my crappy wording.


Sorry, but that's usually wrong.  Audio-grade caps are often much worse in ripple than standard grade.  That's the whole point: audio-grade may sound good, but their specs suck.wink.gif
 

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post #7 of 13
2/27/11 at 4:52pm
Thread Starter 
Wow. Can I not properly write anymore? That's what I meant. The Nichicon KG Audio caps would have lower/worse ripple than other similar non-audio caps.
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post #8 of 13
2/27/11 at 6:58pm


 

Quote:
Originally Posted by TheLaw View Post

Wow. Can I not properly write anymore? That's what I meant. The Nichicon KG Audio caps would have lower/worse ripple than other similar non-audio caps.


One should not assume anything.

 

Check the datasheets and you will learn something as I did.

 

 

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post #9 of 13
2/27/11 at 7:00pm
Thread Starter 
=O ?
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post #10 of 13
2/27/11 at 7:04pm

Read datasheets for ripple current at your required voltage and capacitance of a few caps.

 

I'm not going to hand you the answer.

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post #11 of 13
2/27/11 at 7:31pm

Check this monster out...it can do about 20 amps...

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post #12 of 13
2/27/11 at 7:33pm
Quote:
Originally Posted by TheLaw View Post

Wow. Can I not properly write anymore? That's what I meant. The Nichicon KG Audio caps would have lower/worse ripple than other similar non-audio caps.


No, you were right on that one.  I was thinking worse is less ripple protection, but the rating is actually higher on the better cap.  My mistake.

 

I think cobaltmute is trying to point out that there are exceptions, that's all.  Ultimately, it depends on the power supply and amp design.  If your amp design/power supply has an inherently high psrr, then standard or "power-grade" caps are what you want - because, as you pointed out - the ripple rating is much higher on those caps.  On the other hand, if you're dealing with a run-of-the-mill power supply and amp design (not optimized for psrr), then you may still be better off with audio-grade caps.  This is because the audio quality will filter all the way through the amp into the sound output - non-audio-grade caps, bad sound - even if they're in the power supply.  Most of the stuff around here is inherently high in psrr.  Where you see audio caps making a difference in the power supply is in commercial hi-fi components - CD players, receivers, tuners, etc.  There you may have noticeable improvements in sound quality by bypassing power electrolytics with some audio-grade film caps, for instance, etc., etc.
 

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post #13 of 13
2/28/11 at 1:55am

Please don't spent too much money for audio grade parts for lm3886 amp. It's no use. Just audio caps in signal cap. That amp is maybe "cool", but it's nowhere near as good discrete amp (bipolar/mosfet). Choose wisely.

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