[sdiy] PPG Wave SSM2044 filter

[Colin f]

> > in the MIDIbox forum i read it would affect the resonance (no proof 
> > though).
> 
> Resonance happens at the freq where combined phase shift from 
> all four stages is 180 degrees. Changing one capacitor 
> changes the phase shift and thus resonant frequency.

But do we think PPG were after a subtle change in filter response ?
Or was it simply that a 620p cap was 2 pfennig cheaper than 820p ?

Cheers,
Colin f