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Post by flateric on Apr 18, 2011 15:52:47 GMT -5
Looking for a very simple wiring of pot/footswitch and cap to act as passive volume cut pedal for a pal who plays very high gain and needs a solo boost, like notching up the guitar vol for solos by use of footswitch.
I built one for someone a couple of years ago but I can't remember where I got the circuit from! Main issue will be choice of pot value and capacitor to minimise treble bleed when the pot is cutting the gain.
So when set to OFF the pedal routes the guitar signal thru a variable resistor to give a lower Db rhythm sound. Stomping the pedal turns 'on' the boost by bypassing the pot. Simple.
Any hints for pot and cap values chaps?
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Post by JohnH on Apr 18, 2011 19:28:34 GMT -5
I'd suggest a 500k log taper pot, and wire the switch so it is completely cut out for boost, so it then adds no loading to the guitar. Whether it needs a treble blled circuit will depend....
If he is running really high gain, and wants a very big cut to acheive a cleanish sound, then TB may not be needed. They tend to be most important for making smaller cuts, similar to turning a volume pot down to say 7 or 6 from 10 max. Also, if this pedal is just a short patch cord away from the next active stompbox down stream (eg a Boss tuner pedal, with a buffer), then again TB wont be needed.
If it has 10' or cord after the vol pedal, before being connected to an active circuit, then Id go with 1nF in parallel with 150k (or maybe 220k) for starters, and experiment from there.
John
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Post by flateric on Apr 19, 2011 2:35:49 GMT -5
He's not after a clean rhythm sound, just a significant Db boost for solos. If he had a cleaner sound with a bit more headroom for rhythm he could just use an eq pedal or mosfet boost or tubescreamer type pedal for solos, trouble is the preamp is so saturated already that any further boost just saturates and compresses further. That's why I thought a passive vol cut would be a better option for him.
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Post by flateric on May 1, 2011 5:46:58 GMT -5
Pedal done - 500k log pot used with 150k resistor in parallel to 1nF cap across the middle and outer pot lug. The other pot lug solders to ground, works fine and the treble bleed cap and resistor preserves the treble for lower vol rhythm parts.
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Post by JFrankParnell on May 1, 2011 12:21:28 GMT -5
Working as expected? Cuz, I was thinking, the guy probly just turned up his rhythm vol so much that the 'solo' switch just overloaded the preamp again, like an active boost would!  |
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Post by flateric on May 1, 2011 16:57:04 GMT -5
ha! Working as I'd expect, I guess. For him, he needs discipline to leave some headroom in his amp settings so that removing the vol cut functions properly as a solo boost, the vol cut has to be in quite far to get the Db down in a heavily overdriven JCM900.
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