Author Topic: eh bad stone vol recovery need help!  (Read 1419 times)


eh bad stone vol recovery need help!
« on: May 03, 2010, 08:46:47 AM »
sorry to trouble you guys but i notice from doing searches around the web that some guys have cured the vol drop on the bad stone with an ' opamp vol recovery stage and vol pot '.
im not very skilled in building [ have made a fuzz / tonebender and a rangemaster and done simple amp mods maintenance ] and i wonder if any of you would be able to help guide me in how to do this mod to my bad stone?
im using mains power for the pedal so would want to build a little mother board with opamp stage and maybe a trim pot for final volume to 'set and forget' once its all locked up inside the box.
would anyone be able to guide me to a simple opamp circuit i could build on stripboard with a trimpot and also tell me where and how to wire it to my bad stone board?

i have the final version bad stone with the 3 knobs and large orange lettering 'BAD STONE' on the case.
if its too much hassle its no problem , just thought id ask!
cheers and thanks - robert
Joined: 27 Apr 2010, 19:50
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eh bad stone vol recovery
« Reply #1 on: July 23, 2010, 01:03:53 PM »
i've got the same issue - limited experience with e.e. and a v.3 bad stone with a HUGE volume drop [mine actually has a TB and topmounted 'manual' footswitch].  i love the damn thing and am searching for an answer.
i've read that removing an 'output resistor' or replacing it with a lower value can negate the drop: i think if you remove it altogether, there might actually be a massive, swooping gain, possibly?  how about dropping the opamp w/ pot in there?
also, the schematics i've found have me confused: - i think this might be for the rocker pedal version [kinda like a wah or the dunlop variphase] - for v.2 with two pots and toggle

has anyone ever traced out the v.3 with three pots?


Re: eh bad stone vol recovery need help!
« Reply #2 on: July 24, 2010, 07:11:21 AM »
I can't open that first schematic, the link seems to send me to somet else. On that second schematic, there doesn't seem to be any summing / mixing amplification. So I'd say sticking a simple non-inverting amplifier on the end could boost the output a bit, I'd choose the non-inverting as it has a higher input impedance, remember though that you need a halfway voltage bias. Then simple setup a pot as a voltage divider for a volume control.