[sdiy] PPG Wave SSM2044 filter

Matthias.Herrmann at jeppesen.com Matthias.Herrmann at jeppesen.com
Fri Jan 22 08:31:24 CET 2010


synth-diy-bounces at dropmix.xs4all.nl wrote on 01/22/2010 02:54:49 AM:
> Does anyone know/care to speculate on why the PPG Wave used a non- 
> standard capacitor value for the final stage of the filter?
> 
> Would it affect the filter's rolloff or resonance?

in the MIDIbox forum i read it would affect the resonance (no proof 
though). however, if you change the filter caps values and keep the ratio 
it would only affect the cutoff, as you mention.

source:
http://www.midibox.org/dokuwiki/doku.php?id=ssm2044_pcb

cheers,
matthias
___
www.fonitronik.com


> 
> Most designs follow the datasheet and use 10n for the first three, 
> and 820p for the last one. PPG Wave uses 620p.
> The Korg Trident/Monopoly use 6n8 and 560p, but this doesn't actually 
> change the ratio at all, only the basic cutoff.
> 
> http://www.electricdruid.com/index.php?page=info.ssm2044
> 
> Thanks,
> Tom
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