[sdiy] VCF caps in modern synths

Gordonjcp gordonjcp at gjcp.net
Mon Jan 18 01:07:16 CET 2021

On Fri, Jan 08, 2021 at 03:29:44PM +0000, Mike Bryant wrote:
> >Yesterday I did some very non-scientific testing of 3320 4pole BPF built using C0G vs polypropylenes. The test may have been more about the tolerances of the caps rather than the dielectric, since my polys are 2.5% vs the C0Gs at 5%. I noticed that at lower frequencies, the polypropylene version would go into oscillation before the C0G version. Any thoughts on this?
> Was this SMD or through hole ?   It’s possibly down to lead inductance or series resistance being higher in the C0G.

Lead inductance would be tiny, negligible at audio.  If your VCF is oscillating in the low GHz range you might have issues.


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