[sdiy] Oscillator caps - please help!

[dj hohum]

I know that different people take different approaches, but, I prefer
to start modding or rebuilding from a working machine. Although I
doubt that different caps would be that audible, you might find, for
example, that changing the cap types changes the sound.

Although some projects (see the CMS website) essentially demand a
ground up rebuild, I would suspect that a sixties solid state organ
doesn't. I once reverse engineered a voice card for a friend's farfisa
and the substitutions that I made (we just needed a keyboard for our
band, heh) sounded noticeably different from the original.

At any rate, I personally use whatever's on hand unless "I" can hear
the difference that a cheaper substitution makes. I would use  just
about anything that's as least as stable as what's in there already.
I'll let the experts chime in but if you want stability then, yes,
polyprop is the way to go. Here's a quick guide with a slight RF slant
but useful nonetheless

http://www.interq.or.jp/japan/se-inoue/e_capa.htm

The real question is, do you actually want that kind of stability?

daryl

On 8/14/07, Antti Pitkämäki <anpitkam at hotmail.com> wrote:
> Uh, I just realized that the value of 82nF is the only value I can't find,
> and that I could easily create the value by combining two polyprop caps, so
> I don't really have a very bad problem anymore. But hmm, I guess the
> question is still interesting - what are the best caps for stable
> oscillators, especially the kind of coil oscillators that are in combo
> organs? Are polypropylene caps the best or are there other ones that are
> just as good?
>
> Antti P.
>
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