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ampage archive
Vintage threads from the first ten years
Volume Pedal De-Scratcher
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 1/11/2000 3:36 AM |
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Mike |
Volume Pedal De-Scratcher I built Craig Anderton's Volume Pedal De-Scratcher an put it into a Korg Phase/Wah/Double Wah pedal. Using the existing 6P2T switch, I eliminated the "Auto" feature and added the volume pedal circuit. The 6P2T switches the Input, Output, Power, and the 3 terminals of the pot for "true bypass" type switching. Only problem is the volume pedal rolls off all the highs. What can I do? Does C1 (47pF) control the rolloff? |
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| 1/11/2000 12:41 PM |
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| AMZ |
C1 is providing a low pass rolloff. Reduce it to 10pF and see if that helps any. -Jack | |
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| 1/16/2000 12:48 AM |
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| Mike |
No luck. I even tried driving the VPD with a buffered output. I sure there is SOMETHING wrong. It sounds terrible. There is also a slight drop in volume even with the pedal maxed. Has anybody built this with success? I'm using a CA3080E & TL071CN. The POT measures 650k full open and 0 ohms full closed across legs 2 & 3. 740k and 1.1meg across legs 1 & 2. |
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| 1/22/2000 4:08 PM |
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| Mark Hammer | No particular advice to offer, but I can say that I have built it and the schematic is accurate. Not sure what kind of 3080 you are using, but sometimes the legs on the metal can ones don't sit perfectly in the chip socket, so you may want to check the seating, or even time the legs a bit tomake the fit snugger, if you are using the metal can version. Just a thought. Do get it working, though, since it is a nice smooth sweep. |
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| 1/22/2000 4:38 PM |
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| R.G. |
I've built this one. It worked the first time. I was using the DIP packaged 3080, no socket. I wonder if the 650K pot is too big a value carry enough current to get the gain up on the 3080? I can't remember what value the pot was in mine. |
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| 1/22/2000 7:29 PM |
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| Mike |
The pedal actually worked, it just sounded terrible. There were no highs. Did either of you have the same tone-sucking problem? Unfortunately, I gave up on it and went with a passive volume control setup with a 1nF cap across lugs 2 and 3. Sounds much better, I guess the large pot value supports the passive setup. But, if it starts to crackle.... |
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| 1/23/2000 12:08 AM |
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| John Catto |
I built one of these years ago when the article came out, in a Crybaby case. I've used it ever since - no tone sucking so somethings up. |
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