[sdiy] VCF caps in modern synths

ColinMuirDorward colindorward at gmail.com
Mon Jan 18 17:49:49 CET 2021


 Was there an audible difference between the two capacitor types with the
same frequency/resonance
setting on the filter?

If this question was for me, then here is my answer: In my 4pole 3320 BPF,
the polypropylenes sound slightly better. The obvious difference is that at
lower frequency settings, they go into self-oscillation more readily than
the ceramics. To my biased ear, the ceramics make some small distortion
perhaps, or for some reason add a slight edge to the sound. I did do a
blind test using a 2pole 2164 SVF and the difference there is more
noticeable than in any other filter I've tested. Here, the polys are a
clear win. I want to use words like "liquid, juicy, lush" for the polys vs
"bite, edge, grit" for the ceramics. However those are too strong words to
describe a very subtle difference. I am waiting to find the right modern
mono synth that I can do a capacitor "upgrade" on and test if it's possible
to perceive a change in the sound in a factory-made unit. I have an uno
synth on the way (was on sale for $135cad?!), perhaps I'll be lucky enough
to find space inside that tiny case for four WIMAs.

I also would like to add a big thanks for all the conversation on this
topic! Every time I say the word "capacitor" around here, I learn so much!
Last time it was about bypass caps, and now this topic as well has been
very good reading.

Cheers,
Colin

On Sun, Jan 17, 2021 at 9:36 PM Tristan <tu at alphalink.com.au> wrote:

> Was there an audible difference between the two capacitor types with the
> same frequency/resonance
> setting on the filter?
>
> /Tristan
>
> On Mon, Jan 18th, 2021 at 11:19 AM, Mike Bryant <
> mbryant at futurehorizons.com> wrote:
>
> > Agreed lead inductance would be tiny.  I was thinking more of inductive
> > coupling between the lead inductances if the capacitors are mounted close
> > together, or close to a high level signal.  This can easily happen in
> the MHz
> > range and adversely affect the audio performance.
> >
> > -----Original Message-----
> > From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
> > Gordonjcp
> > Sent: 18 January 2021 00:07
> > To: synth-diy at synth-diy.org
> > Subject: Re: [sdiy] VCF caps in modern synths
> >
> > 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.
> >
> > --
> > Gordonjcp
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> > Selling or trading? Use marketplace at synth-diy.org
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> > Selling or trading? Use marketplace at synth-diy.org
> >
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> Selling or trading? Use marketplace at synth-diy.org
>


-- 
https://www.instagram.com/colinmuirdorward/
-
<https://www.instagram.com/colinmuirdorward/>
https://www.instagram.com/ssdp_synthesis/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20210118/4d72743e/attachment.htm>


More information about the Synth-diy mailing list