Question about Pyramid caps

Question about Pyramid caps

I'm restoring a 40+ year old Scott preamplifier.

How well do the Pyramid brand plastic-encapsulated paper / foil caps hold up
over time, in terms of leakage? Is it necessary to replace them wholesale?

Thanks


Jon

Re: Question about Pyramid caps

On Thu, 08 May 2008 00:45:48 -0400, Jon Yaeger <jono_1@bellsouth . net > wrote:

>How well do the Pyramid brand plastic-encapsulated paper / foil caps hold up
>over time, in terms of leakage?

AFAICT they age more garcefully than their Sprague or Astron equivalents,
with maybe 1 out of 10 badly leaking after 30+ years.

> Is it necessary to replace them wholesale?

I would test them, then decide. If you don't have a proper cap tester you
may lift one end and look for DC.

Anyway, good caps are cheap and plentiful...

Re: Question about Pyramid caps


"Jon Yaeger" <jono_1@bellsouth . net > wrote in message
news:C447FDBC.BDE47%jono_1@bellsouth . net ...
> I'm restoring a 40+ year old Scott preamplifier.
>
> How well do the Pyramid brand plastic-encapsulated paper / foil caps hold
up
> over time, in terms of leakage? Is it necessary to replace them
wholesale?

Hi Jon: I would. I acquired a large selection of NOS paper caps a few
years ago. I recall that almost everything except the Sprague Orange Drops,
Solid Impregnant Black Beauties, and Arco Brown Radials (Chocolate drops?)
leaked. The impregnants are all proprietary and most failed, even some
hermetically sealed caps. Some of the military metal can caps are OK. I
recall that Westcap metal can are OK. Of course the Vit-Q is fine. I have
two 0-400V d.c. power supplies to series for some serious testing. The
Orange drops (paper/mylar until about 1980 when they became SBE) and Arco
radials have far less leakage at 150% of rated voltage than at 100%.
Despite what the scientific crowd says, the vintage paper caps can give the
circuit a uinique and in my opinion pleasing sound. I am in the process of
setting up a website to sell parts. w w w .33audio . com . Some of the pages are
uploaded. I have some 400V Arco radials for sale if you need some. I have
used these for several years and have never had a problem with them. Mark
>
> Thanks
>
>
> Jon
>

Re: Question about Pyramid caps

On Thu, 8 May 2008 04:12:45 -0700, "Marko" <markhu@xxxnetscape . com > wrote:

>Despite what the scientific crowd says, the vintage paper caps can give the
>circuit a uinique and in my opinion pleasing sound.

PCB-impregnated paper caps are best. Hmmm, the sweet sound of
polychlorinated biphenyls.
:-)