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DIY Stompboxes => Building your own stompbox => Topic started by: MmmPedals on July 17, 2011, 10:33:19 AM

Title: Input cap blend pot crackling
Post by: MmmPedals on July 17, 2011, 10:33:19 AM
I built a brian may boost (http://www.generalguitargadgets.com/pdf/ggg_geb_bmay_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a (http://www.generalguitargadgets.com/pdf/ggg_geb_bmay_sc.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a)) and put a pot to act as a blend of a .0047uf film and 3.3uf electrolytic cap. The control crackles as does the volume knob on my guitar.
Is something wired incorrect?
Is there a way to solve this?
Title: Re: Input cap blend pot crackling
Post by: Joe Hart on July 17, 2011, 12:34:52 PM
I believe it is normal for the knob to crackle (I think it's something like DC on the pot). And maybe DC is going through the cord to your guitar, too? Or maybe the crackle on your guitar volume was always there, but the Rangemaster makes it more apparent? I hope this helps!
-Joe Hart
Title: Re: Input cap blend pot crackling
Post by: joegagan on July 17, 2011, 12:57:27 PM
this is a bit of a problem. my brontoboost does this sometimes as well, which has a control almost identical to yours. even with a buffer in between. but the crackling isn't bad, i try to make changes during the music to mask it. is that bad? when i put a new pot in my tele it helps a lot.
Title: Re: Input cap blend pot crackling
Post by: John Lyons on July 17, 2011, 03:12:41 PM
Measure the tip of the input jack with the pedal "on".
You should not be seeing any DC voltage.
If you do then that's your problem.
Put a 1M resistor from the circuit input to ground
to bleed off any DC voltage.
Title: Re: Input cap blend pot crackling
Post by: MmmPedals on July 17, 2011, 07:09:54 PM
there is already a 120k resistor to ground in the above schem.