[sdiy] Good 24db/oct HP-LP-BP-Notch filter Schematics ??

Andrew Simper andy at cytomic.com
Fri Mar 7 02:39:49 CET 2014

On 7 March 2014 01:26, Neil Johnson <neil.johnson71 at gmail.com> wrote:
>>> Unless the schematic is available it might be fun to reverse-engineer it?
>> Isn't that what we're doing?!
> Without actually sitting down and working out the schematic we're just
> kinds dancing round the edge.
> Maybe someone who cares could send an email to Analogue Systems and
> ask them directly?  Might save a bit of time??
>> Do you think it's 2-pole then, Neil?
> Evidence suggests that is the case.  I don't have one to test so I
> can't say with any certainty.  If someone sends me one I can plug it
> into the spectrum analyser and confirm its operation.  But maybe an
> email to the maker would be quicker.
> Neil

When I played with it ages ago it sounded like a 2 pole SVF (a good
sounding one, I recommend this unit!). I replied to the OP saying that
the schematic for the RS110 would be useless if you want 4 pole
operation since the RS110 is only a 2 pole filter, but then deleted
the email and didn't send it since I read the "documentation" which
explicitly stated 4 pole.

Still this should be easy enough to sort out is someone can listen to
the resonance output and possibly plot the frequency response. If the
resonance output is bandpass then it is an SVF.

I'll email AS and find out. This filter sounds great and I would like
to know more.


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