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Do oil filled caps have a memory

elusive

elusive

AK Subscriber
Subscriber
I've never built a custom amp using metal can Pyranol filled capacitors. However, I have read that their very low ESR can be a huge benefit. So, for my next 7591 amp, I intend to use some.

My question is if these types of caps retain any sort of memory in regards to polarity. IE; over time do these non-polarized caps become polarized? If they do, I would not want to hook them up backwards.

Any advise or experience? Thanks.
 
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They can become polorized after long periods of being installed a certain way. Pak can splain it better than I can,
 
jaymanaa said:
They can become polorized after long periods of being installed a certain way. Pak can splain it better than I can,
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Not what I want to hear... but thanks. Wonder if they "go back to normal" after not being used for a long time....
 
elusive said:
Not what I want to hear... but thanks. Wonder if they "go back to normal" after not being used for a long time....
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I don't even know what the repercussions would be of hooking one up backwards that had taken on a polarity. Where's Pak?
 
toxcrusadr said:
I expect most (99.9%) of the hits are going to apply to electrolytics rather than nonpolar oil filled caps.
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yes i reckon so .. wondering if they had a shot of ac at full working voltage if it would be a good test ?:scratch2:
or maybe at the voltage they work at in the design just in case they have lost voltage tolerance .
 
These GE caps are rated at 1000VDC. I doubt I would want to be anywhere near them at full voltage... "just to see".

I could apply a smaller voltage on them and measure ripple, then swap 'em and see what it looks like.

...but being your average chicken$h!t, I'll wait and see if anyone knows the real answer.
 
"Dielectric Absorption" causes all caps to regenerate charge of similar polarity after the terminals are shorted, but even with poor dielectric material, it eventually dissipates without lasting consequences. Well, except for special cases such as electret microphones.

Edit: Okay, there's more to this story... In the electrical power industry, big caps are always stored with a shorting link attached because they can and do regenerate a lethal amount of charge even after months or years offline.
 
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elusive said:
These GE caps are rated at 1000VDC. I doubt I would want to be anywhere near them at full voltage... "just to see".

I could apply a smaller voltage on them and measure ripple, then swap 'em and see what it looks like.

...but being your average chicken$h!t, I'll wait and see if anyone knows the real answer.
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I wouldn't worry about blowing them up, just start with like 100 volts and work your way up slowly. You could always throw a towel on it just in case.:D
 
doesn't answer the question....however quoted from the man with regards to GE motr run caps:

"The models are generally started by "97F*******". they are all metalized polypropylene and 'Dielektrol vi'( the oil, just a GE name, reminicient of Pyranol and Clorinol, its PCB based predescessors). I have also been experimenting with ASC capacitors of the same sort of construction, polyprop/oil and find them to be very nice, esp in the coupling/output stage of a pre-amp/linestage. I have Auricaps in the power suply and am going to replace them with the ASC oilers when next under the hood. That simple circuit, single triode section per channel just blows me away when ever I listen to it....seems hard to believe there is much room for improvement.
regards,
Douglas"






I really like GE and ASC motor run.... not going to fool with PCBs here, or used motor runs for that matter...when I can help it... unless they are fairly new and bought at a nice discount. I picked up 6 GE 47uf motor runs for like $35 shipped.
 
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Sam Cogley said:
Because those big ol' oil caps last damn near forever?
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Also because the ESR is much lower than most new caps. Unless someone has found high quality oil filled, NOT made in China.

Yes, I could throw a towel over it... 'cept I left my last good towel wrapped around a certain Stromberg Carlson 220C. :D

...I guess the concensus is to just try it.
Well, we'll have to wait a bit. I got two Packard Bell's on the bench and a H/K 224 to finish first.

Then I can start playing with these caps and my Scott 208 clone.
 
BinaryMike said:
"Dielectric Absorption" causes all caps to regenerate charge of similar polarity after the terminals are shorted, but even with poor dielectric material, it eventually dissipates without lasting consequences. Well, except for special cases such as electret microphones.

Edit: Okay, there's more to this story... In the electrical power industry, big caps are always stored with a shorting link attached because they can and do regenerate a lethal amount of charge even after months or years offline.
Click to expand...

That is exactly my experience with PIO caps esp the Russian K40s. These things have very demonstrable DA issues to the point I'm reluctant to use them in audio stages. It would be interesting to see some credible research as to the audibility of DA. For power supply apps, I doubt DA is an issue.
 
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