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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>In 2016 I built a Moog 904A VCLPF clone<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>from Moog’s modular original schematics.<br>I’m VERY happy about the resulting behaviour of it.<br>Very fatty and precise sound !<br>I used matched pairs of BC550C NPN’s for the ladder job.<br>I supposed the 904A VCF design is very close to the one the minimoog uses..<br>Anyway, all my projects files are open source for anybody..<br><br><o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><a href="http://www.arcenson.com/projects/Modular/M104A_Lowpass_Filter_Moog_904A_clone/Specifications/M104A_VCLPF_schematic.pdf">http://www.arcenson.com/projects/Modular/M104A_Lowpass_Filter_Moog_904A_clone/Specifications/M104A_VCLPF_schematic.pdf</a><o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><img border=0 width=822 height=625 style='width:8.5625in;height:6.5104in' id="Image_x0020_2" src="cid:image001.jpg@01D99B7A.2077AE50"></span><span style='mso-fareast-language:EN-US'><br><img border=0 width=299 height=613 style='width:3.1145in;height:6.3854in' id="Image_x0020_3" src="cid:image002.jpg@01D99B7A.2077AE50"><o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=FR>De :</span></b><span lang=FR> Synth-diy <synth-diy-bounces@synth-diy.org> <b>De la part de</b> David G Dixon via Synth-diy<br><b>Envoyé :</b> 10 juin 2023 00:09<br><b>À :</b> synth-diy@synth-diy.org<br><b>Objet :</b> [sdiy] Yves Usson's Minimoog Filter<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Hello SDIY Team,<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>I've built a ladder filter on my own PCB layout from Yves Usson's Minimoog ladder filter schematic, and I must confess that the results are less than stellar. The filter works, but not terribly well, and it sounds nothing like a Minimoog. I used 2N3904 and 2N3906 instead of BC547 and BC557, but I matched all of the transistor pairs in the ladder, and matched the four transistors at the top and bottom of the ladder as well as the other four transistors, using Ian Fritz's transistor matching circuit (which I also laid out and built on a PCB). I did not try to match the one PNP to the current driving NPN below the bottom of the ladder.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Does anyone here have any experience with this schematic? Will it change anything if I replace the 3904s with 547s, etc? Everything else was exactly as specified in the schematic. This was my second attempt to build from an Yves Usson ladder filter schematic. My "Raging Bull" Taurus filter didn't work at all.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>I just want to know if there is some fundamental flaw in this schematic before I spend too much more time with it. Any insights would be most appreciated.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>Dave Dixon<o:p></o:p></p></div></div></div></body></html>