[sdiy] understanding the CAP arrangement on the PT2399 (filters)

[George Hearn]

To help work things out, gain-phase plots have been added to the website now
to show the frequency response of the input anti-aliasing and output
reconstruction filters for the PT2399 VC Delay.  The input filter is a
12db/Oct LPF and the output filter is a 18db/Oct LPF.  George

http://sites.google.com/site/hearnmorley/synth-diy-resources

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Dan Snazelle
Sent: 06 October 2009 03:23
To: synthdiy
Subject: [sdiy] understanding the CAP arrangement on the PT2399 (filters)


looking at

http://sites.google.com/site/hearnmorley/synth-diy-resources/GHSYN2bWeb.pdf?
attredirects=0

or even at the PT2399 datasheet, i have never understood the signal flow in
the "internal opamps"

to me it looks like the input is connecting VIA r5 to the first opamp which
has a 1n in its feedback loop. but is r6 connecting into the next opamp or
into the feedback loop of the first one? and there is similar confusion on
following the path (and determining the cutoffs) on the additional internal
opamps

thanks for any help

 		 	   		  
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