Single Resistor Turns Guv'nor into Crunchenstein

[Nick C.]

My GV2 has been gathering a lot of dust because it just didn't work well with my Fender amp. It never had much high end to cut through the mix. Looking to mod it this thread gave me an idea.
http://www.diystompboxes.com/smfforum/index.php?topic=56879.0

Refer to GGG schematic:
http://www.generalguitargadgets.com/pdf/ggg_mgv_org_sc.pdf

The problem area is in the 2nd opamp which has a gain of 68x and a low pass at about 1KHz. There's my highs! The mods in the thread increase the gain and shift more gain to the 1st opamp, a 720hz high pass. I figured I could do the same thing by changing R6 (R11 on my GV2) to a lower value. This would also raise the lowpass to boot.

1st I tried replacing the 680k R6 with a 220k which would give me a low pass of about 3300hz. (that is if the knee is 1/2piRC). This change turned my buttery Fender into a ripper. Tons of high end crunch. Increadable transformation. Problem is that the normally huge bottom was reduced and the gain was low enough that I could max the volume and be just at unity. I decided to compromise and changed R6 to 470k, 1500hz low pass. Now I have plenty of highs, lows and gain for my taste. Not over the top, but a very workable pedal for my rig. Also thinking of changing to R6 back to 680k and C8 from 220pf to 100pf or 50pf and hear what that does.

One resistor=huge transformation! Thought I'd share.

Nick

BTW is 1/2piRC the right calc for the cutoff?

[b_rogers]

i will try this mod when i get home.  ive always hated the lack of highs in this really nice featured pedal. lots of flexiblity, but just cant get thru the mud.