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negativspace
Joined: Dec 25, 2010 Posts: 17 Location: Manhattan, Kansas
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Posted: Tue May 10, 2011 3:45 pm Post subject:
Arp 4072 VCF Bleedthrough Fix Subject description: Clarification of instructions needed! |
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Yves,
I built one of these for a fellow over on Muffwiggler's and we're trying to fix the bleedthrough issue. He forwarded me some instructions you gave him, quoted here:
"The cure is to replace the resonance potentiometer by a dual gang model. Connecting the CW lugs in parallel, the CCW lugs in parallel, and one wiper lug connected to the normal resonance circuit while the other wiper lug connected to the R43 resistor."
I am unclear on one thing - when you say 'connect to R43' do you mean in place of R43, or to its input leg, or to its output leg? Thank you! |
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dstrength
Joined: May 23, 2010 Posts: 17 Location: Mobile, Alabama, USA
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Posted: Sat May 21, 2011 12:48 pm Post subject:
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I think you're just replacing the T-connection on the schematic..so looking at the schematic, remove the T and tie the left side of R43 to the other wiper. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat May 21, 2011 11:58 pm Post subject:
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Ok I am back home.
I mean "connect to" not "replace", this means unsolder the left leg of R43, solder a wire this leg and connect this wire to the wiper lug of the second potentiometer of the dual-gang pot. _________________ Yves |
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negativspace
Joined: Dec 25, 2010 Posts: 17 Location: Manhattan, Kansas
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Posted: Sun May 22, 2011 1:46 am Post subject:
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Perfect. Thanks for the clarification! Thanks to dstrength for the help too. I'm out of town on business right now but I will assemble the module next week and report back. |
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negativspace
Joined: Dec 25, 2010 Posts: 17 Location: Manhattan, Kansas
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Posted: Sun May 29, 2011 10:57 pm Post subject:
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This seems to do the trick. It absolutely kills the bleedthrough and seems to leave the low end intact at high resonance. The resonance control response is altered slightly - self-osc seems to come in differently - but it's neither more- or less-usable... just different. It still sings beautifully in self-oscillation and tracks my entire 5-octave keyboard.
Thanks again. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sun May 29, 2011 11:17 pm Post subject:
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negativspace wrote: | This seems to do the trick. It absolutely kills the bleedthrough and seems to leave the low end intact at high resonance. The resonance control response is altered slightly - self-osc seems to come in differently - but it's neither more- or less-usable... just different. It still sings beautifully in self-oscillation and tracks my entire 5-octave keyboard.
Thanks again. |
Fine then, I will add a note at my site. _________________ Yves |
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Sebo
Joined: Apr 27, 2007 Posts: 564 Location: Argentina
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Posted: Fri Jun 24, 2011 3:49 pm Post subject:
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Hi:
I did the fix and now the bleedthrough is gone.
Thank you Yves!!! _________________ Sebo
---------------------------------------
My Music:
https://www.facebook.com/cosaquitos/ |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Jun 25, 2011 12:05 am Post subject:
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Thanks for the feedback !
I will publish this mod then _________________ Yves |
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djfill
Joined: Jan 10, 2012 Posts: 26 Location: Cardiff, Wales, UK
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Posted: Wed Feb 08, 2012 5:54 am Post subject:
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Hi Guys...
I think I have the 'Bleedthrough' issue and just wanted to confim the symptoms with someone before I try this fix.
When I set the frequency to 0 and increase the reasonance, i can still hear the waveform slightly. Is this bleedthrough? (The answer seems obvious when i put it like this but I just want clarification before i start making a mess of my board.)
Thanks. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Wed Feb 08, 2012 6:14 am Post subject:
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djfill wrote: | Hi Guys...
I think I have the 'Bleedthrough' issue and just wanted to confim the symptoms with someone before I try this fix.
When I set the frequency to 0 and increase the reasonance, i can still hear the waveform slightly. Is this bleedthrough? (The answer seems obvious when i put it like this but I just want clarification before i start making a mess of my board.)
Thanks. |
You answered yourself
Yves _________________ Yves |
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djfill
Joined: Jan 10, 2012 Posts: 26 Location: Cardiff, Wales, UK
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Posted: Wed Feb 08, 2012 6:44 am Post subject:
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yusynth wrote: | djfill wrote: | Hi Guys...
I think I have the 'Bleedthrough' issue and just wanted to confim the symptoms with someone before I try this fix.
When I set the frequency to 0 and increase the reasonance, i can still hear the waveform slightly. Is this bleedthrough? (The answer seems obvious when i put it like this but I just want clarification before i start making a mess of my board.)
Thanks. |
You answered yourself
Yves |
I thought so...thanks Yves! (congrats on the new synth btw...looks great!) |
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sylvainmoreau
Joined: Feb 19, 2013 Posts: 17 Location: paris
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Posted: Wed Jun 26, 2013 5:36 am Post subject:
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sorry i prefer to do a drawing because my english is missing some words here ..
is that correct ?
_________________ arp vcf 4072 in progress |
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sylvainmoreau
Joined: Feb 19, 2013 Posts: 17 Location: paris
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Fri Jun 28, 2013 12:42 pm Post subject:
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Yes you got it right _________________ Yves |
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Pilastik
Joined: May 17, 2010 Posts: 5 Location: Greece
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Posted: Sat Jun 29, 2013 2:49 am Post subject:
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viewing your drawings cw(3/6) will go on the right side and ccw(1/4) will go on the left |
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vladosh
Joined: Aug 02, 2010 Posts: 659 Location: macedonia
Audio files: 46
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Posted: Thu Jul 31, 2014 2:05 am Post subject:
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fixed mine too , thanks for sharing ,the resonance seems nicer this way |
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alanwilder81
Joined: Sep 03, 2016 Posts: 310 Location: italy
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Posted: Wed Jan 25, 2017 8:24 am Post subject:
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hello Yves,
can you please further explain your statement ?
"The cure is to replace the resonance potentiometer by a dual gang model. Connecting the CW lugs in parallel, the CCW lugs in parallel, and one wiper lug connected to the normal resonance circuit while the other wiper lug connected to the R43 resistor."
what's the " normal resonance circuit " the second wiper lug has to be connected to?
thanks |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Wed Jan 25, 2017 10:36 am Post subject:
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Check the drawing six messages above (sylvainmoreau... _________________ Yves |
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alanwilder81
Joined: Sep 03, 2016 Posts: 310 Location: italy
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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alanwilder81
Joined: Sep 03, 2016 Posts: 310 Location: italy
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Thu Jan 26, 2017 6:54 am Post subject:
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Yes that's correct _________________ Yves |
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alanwilder81
Joined: Sep 03, 2016 Posts: 310 Location: italy
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Posted: Thu Jan 26, 2017 6:57 am Post subject:
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thanks a lot, Yves, for sharing with us this wonderful filter and for your technical help. That s priceless !! |
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alanwilder81
Joined: Sep 03, 2016 Posts: 310 Location: italy
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Posted: Sun Aug 27, 2017 2:31 am Post subject:
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Yves,
can you please get me the ARP 4072 schematics you originally drew ? i mean the schematics before the dual pot modification.
many thanks! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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