madbeanpedals::forum

Projects => General Questions => Topic started by: jonnygreentrees on November 24, 2016, 06:03:20 PM

Title: Demo Tape Fuzz build question
Post by: jonnygreentrees on November 24, 2016, 06:03:20 PM
Just finished a Demo Tape Fuzz clone on a board from Jed's Peds and weirdly the gain/trim pot does full gain fully clockwise but also fully anticlockwise with different shades of gain in between. Is this normal?
Title: Re: Demo Tape Fuzz build question
Post by: Betty Wont on November 24, 2016, 06:50:34 PM
That's odd. I'm not familiar with that specific project, but that's not how the DTF works. You may have a solder bridge somewhere causing that, or a bum pot.
Title: Re: Demo Tape Fuzz build question
Post by: jonnygreentrees on November 24, 2016, 06:54:39 PM
cool will have a look for solder bridges and try a new pot
Title: Re: Demo Tape Fuzz build question
Post by: juansolo on November 24, 2016, 07:53:07 PM
Definitely not normal. Gain pot behaves as normal, though it only actually gets fuzzy right at the end of it. Also the vol has a HUGE amount of vol on tap. You'll barley turn the thing on and get unity.
Title: Re: Demo Tape Fuzz build question
Post by: Boba7 on November 24, 2016, 08:55:03 PM
Oh yeah you definitely want a 100k log for volume. It has a LOT of volume on tap. The distortion only comes from the opamp.
A beautiful circuit.
Title: Re: Demo Tape Fuzz build question
Post by: jonnygreentrees on November 24, 2016, 09:32:14 PM
can't see any solder bridges, must be a duff pot
Title: Re: Demo Tape Fuzz build question
Post by: Boba7 on November 24, 2016, 10:31:03 PM
I've never had a bad pot... Pretty sure it's something else. But you might be right.
I had never heard of thoses pcbs.
He seems to use some Madbean drawn schematics (as seen on the build doc of the Tape fuzz)
Title: Re: Demo Tape Fuzz build question
Post by: Betty Wont on November 25, 2016, 02:12:32 AM
Quote from: Boba7 on November 24, 2016, 10:31:03 PM
I've never had a bad pot... Pretty sure it's something else. But you might be right.
I had never heard of thoses pcbs.
He seems to use some Madbean drawn schematics (as seen on the build doc of the Tape fuzz)
I agree it could be something else, but i have gotten a pot with a bad disc in it that behaved similarly. Its easy enough to test with a meter. I haven't heard of the vendor before either.
Title: Re: Demo Tape Fuzz build question
Post by: jonnygreentrees on November 25, 2016, 08:26:07 PM
just measured the resistance on the pot and I'm getting 03.3 ohm at both ends of the sweep on a 20k pot. Definitely something wrong with the pot