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<DIV dir=ltr align=left><SPAN class=394390920-22112022>My advice (which you
emphatically don't need) is to do a Fourier-domain analysis of the circuit and
plot amplitude vs frequency. Maybe something surprising will pop
out.</SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Lanterman, Aaron D
via Synth-diy<BR><B>Sent:</B> Tuesday, November 22, 2022 2:01 AM<BR><B>To:</B>
synth-diy mailing list<BR><B>Subject:</B> [sdiy] Buchla 295 10-band comb filter
topology<BR></FONT><BR></DIV>
<DIV></DIV>
<TABLE style="PADDING-LEFT: 0px; BORDER-COLLAPSE: collapse">
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<TD><FONT
style="PADDING-BOTTOM: 3px; LINE-HEIGHT: 1.6; BACKGROUND-COLOR: #ffecb3; FONT-STYLE: normal; PADDING-LEFT: 3px; PADDING-RIGHT: 3px; FONT-FAMILY: Arial, sans-serif; COLOR: #000000; FONT-SIZE: 12px; FONT-WEIGHT: normal; PADDING-TOP: 3px">[<STRONG>CAUTION:</STRONG>
Non-UBC Email]</FONT></TD></TR></TBODY></TABLE>Does anyone recognize the
topology Don is using here in the bandpass sections?
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<DIV><A
href="http://fluxmonkey.com/historicBuchla/buchlaFiles/Buchla_2950_200.jpg">http://fluxmonkey.com/historicBuchla/buchlaFiles/Buchla_2950_200.jpg</A></DIV>
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<DIV>The low and high bands are 3-pole Sallen-Keys, but I’m not sure what’s
going on in the middle filters. It looks kind of like a multiple feedback
filter, but instead of having a resistor to ground like in Figure 1 here:</DIV>
<DIV><BR></DIV>
<DIV><A
href="https://sound-au.com/project63.htm">https://sound-au.com/project63.htm</A></DIV>
<DIV><BR></DIV>
<DIV>There’s some weirdness with a 3rd capacitor connecting to the resistive
feedback back.</DIV>
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<DIV>
<DIV>Aaron Lanterman, Prof. of ECE, Georgia Tech<BR>My blog on
Education and Innovation: <A
href="https://edupocalypsenow.wordpress.com">https://edupocalypsenow.wordpress.com</A><BR>My
blog on Electronics and Programming: <A
href="https://lantertronics.blogspot.com">https://lantertronics.blogspot.com</A><BR>My
YouTube channel on Electronics and Programming: <A
href="https://www.youtube.com/c/lantertronics">https://www.youtube.com/c/lantertronics</A></DIV>
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