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[Dan Brandesky]

I'm putting together a Mouser order for replacement power supply caps for a Roland SRV-330. Initially, I had decided to look for caps with slightly higher temperature tolerances since these units tend to get really hot, but I see there are also "audio grade" capacitors, such as the UFW series by Nichicon. Should I go for these instead, or does it really matter?

Thanks,
Dan

[Mike Butler (media)]

Do they say specifically and quantitatively what makes these caps "audio grade"?

[Dan Brandesky]

Mike Butler (media) wrote on Sat, 16 August 2008 20:32

Do they say specifically and quantitatively what makes these caps "audio grade"?

Here's a PDF datasheet for one of them: http://products.nichicon.co.jp/en/pdf/XJA043/e-fw.pdf

I don't see anything that specifically states anything about them, though, unless maybe it has something to do with frequency characteristics?

-Dan

[Jason Ellis]

Since they are for the power supply and not in-line with the audio will it matter?

The special audio ones are supposed to have a better ESR (equivilent series resistance) than the non-audio ones FWIW. I have no-idea if ESR is snake-oil or not...

If I were buying I wouldn't give them a second thought - these are for a power supply - and the SRV-330 is a bit noisy - you won't hear the difference [I have one too - I like the plates, the halls suck]

[Mac Kerr]

Dan Brandesky wrote on Sat, 16 August 2008 20:52

Mike Butler (media) wrote on Sat, 16 August 2008 20:32 Do they say specifically and quantitatively what makes these caps "audio grade"? Here's a PDF datasheet for one of them: http://products.nichicon.co.jp/en/pdf/XJA043/e-fw.pdf I don't see anything that specifically states anything about them, though, unless maybe it has something to do with frequency characteristics? -Dan

But you're not using them for audio. You are using them in a power supply. I can't design a circuit, but I assume audio grade components would be used in an audio path, not a power supply.

Mac

[Dan Brandesky]

Good point, Mac. I think I would really rather have a bit more temperature tolerance anyway. I doubt it will make a difference, but you never know. The old ones look well done, so I figure it can't hurt. I think I'm going to have to rack both my "new" SDE and SRV with spaces in between them, these units seem to have some intense heat problems when they're racked in a "stack". I got the SDE cheap because the previous owner said it periodically froze up, but it seems that that too might be related to heat problems. Oh well, small price to pay I suppose for, well, a small price tag.  

-Dan

[John Roberts {JR}]

There are several newer series of electrolytic caps with low ESR (equivalent series resistance) and low ESL (equivalent series inductance) specifically for improved performance in switching power supplies. I guess lower ESR would be a good thing if the cap was being used in a passive speaker crossover, but electrolytic are  generally a low fi solution for that application.

The general criteria or complaint about electrolytic capacitors for audio use is a more subtle asymmetry or nonlinearity when the capacitor is not biased at some DC voltage and passing a AC waveform. In principle 1/2 the waveform is applying a reverse polarity across the capacitor.

AFAIK there is no obvious specification to quantify this elusive "audio" use nonlinearity, and conservative engineers are justified to question if there's any there there. There are apparently many customers who want to buy "audio" quality caps, and the customer is always right so several mfrs have stepped up to meet the demand.

As Mac and others have pointed out this is moot for your power supply reservoir application. Elevated temperature is an enemy of electrolytic capacitors as it accelerates electrolyte loss. IIRC higher temp caps (105') are generally not much more expensive than normal (85').

JR

[Dan Brandesky]

Thanks, John. I did go with the higher temp caps; I think most are rated at 105', and I also got some that go up to 125', so that will hopefully work for me.

It is kind of annoying that I will have to rack these units spaced apart to keep them from overheating and going bookoo weird, such as the SDE-1000 freezeups. Oh well. Maybe I'll make some nice filler spacers out of luon for the front of the rack   .

-Dan

[SteveKirby]

J.R.  Wouldn't a lower ESR cap work better in a power supply as well?  I would think it wouldn't have to be bypassed as heavily.

[John Roberts {JR}]

SteveKirby wrote on Mon, 18 August 2008 19:22

J.R.  Wouldn't a lower ESR cap work better in a power supply as well?  I would think it wouldn't have to be bypassed as heavily.

In principle yes...   If they cost the same as standard should be no brainer (for PS application).

JR

[Andy Peters]

SteveKirby wrote on Mon, 18 August 2008 17:22

J.R.  Wouldn't a lower ESR cap work better in a power supply as well?  I would think it wouldn't have to be bypassed as heavily.

Lower ESR is almost always better, except with some LDO regulators that specify a range of acceptable ESR values. Those regulators are happy with most aluminum electrolytics but they go batty with the new lost-cost  high-value ceramics that offer quite-low ESR.

-a