[sdiy] (no subject)

[Richie Burnett]

> Sorry I opened the damn can of worms again!
> I thought it was a simple question about the benefits tolerance
> versus dielectric material...well, it *was*, once.

I shouldn't worry about covering old ground.  For me at least this is a fresh
discussion and an interesting one.

I think the key factor influencing the "brittleness" or "edgey" sound that you
got with old cermaic capacitors might be their voltage dependent capacitance
that was mentioned previously.  In it's simplest sense you can imagine capacitor
plates pulling together when they are oppositely charged.  This would mean that
the cutoff frequency of the VCF would vary slightly as the audio signal altered
the voltage across the capacitors.  The end result will be something that sounds
like mild ring-modulation or filter cutoff FM depending on how high the voltage
coefficient of the ceramic capacitors was!

Slight filter FM would certainly have the effect of making the filter sound
brighter and more brittle.

-Richie,