Electronotes 12-pole filter design???

[mark verbos]

Can anyone direct me to a copy of the Electronotes 12 pole filter 
Juergen Haible refers to in the description of his Frequency shifter? I 
am about to attempt his design, but have no knowledge of this circuit. I 
have no experience with Frequency shifters, but I have heard them in 
use. I need one. Any help? Juergen?
--
mark verbos

"I think the future of analog modulars is to build them yourself." 

verbos at on-q.com
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