A few months ago I copied the Marshall Guv'nor GV-2 Deep Circuit on a vero and installed it into an GV1 clone I built. (It rocks!) I've since been wondering about how to change the frequency of this circuit so I could switch between settings.
According to this posting here:
http://www.marshallforum.com/threads/marshall-gv2-guvnor-plus-overdrive-distortion-pedal-how-it-works-mods.93225/ (http://www.marshallforum.com/threads/marshall-gv2-guvnor-plus-overdrive-distortion-pedal-how-it-works-mods.93225/)
"The Deep control is focussed on very low bass, below guitar range. The hump could be shifted up by decreasing two caps (C16 and C17) in the deep circuit to give more action around 80hz."
What I'd like to know is just what values are needed for C16 and C17 to raise the frequency from the listed 30hz to the suggested 80hz? And how is that determined for this circuit with the two caps in parallel with each other?
Here's the GV2 schematic and my layout:
(https://i.postimg.cc/G4xx9gPw/gv2-schematic.jpg) (https://postimg.cc/G4xx9gPw)
(https://i.postimg.cc/cg99gwHx/Guv-nor-GV-2-Buffer-and-Deep-Circuit-Addon.png) (https://postimg.cc/cg99gwHx)
I would like to try this daughter board when I'll build my first Guv'Nor.
This is a GV-2 schematic I found, but I think there's something wrong with the Deep control: R20 100k is in parallel with C16 68nF, but that makes it work weird in my emulator:
(https://www.jocidapark.com.au/circuits//Marshall%20forum/GuvschematicGV2_zpsydic36kg.gif)
There's another schematic here. And the Deep control works better.
(https://www.lellolombardi.it/wp/wp-content/uploads/2016/01/Marshall-GV-2-schematic.jpg)
This is my emulator (a rev log pot seems more balanced) and, though I tested it putting the old original Guv'Nor circuit in front of the Deep control part, I guess is it clear. (GV-2 tonestack could give more bass and less treble).
(https://i.imgur.com/qy5OWEP.jpg)
And here a video that show the frequency of the Deep control.
https://youtu.be/rbiDg2mqTXU?t=103
Looking all this I didn't find the frequency so low. It didn't depends from Deep, at least I guess.
I'm looking some mods that change the Deep control and see how that could be useful, and I found this:
Replace these parts:
R19(4.7kOhm)->10kOhm
R21(470kOhm)->470kOhm->150kOhm
R9(1mOhm)->220kOhm
C23(22pf)->47pf
(https://i.imgur.com/0ZVMJBt.png)
I tried to emulate it, but it seems ruin the deep control. It minimizes too much the peak at max setting, at min setting cut bass and boost mid, and I got a drop of volume. Is really that the results?
Wow, I don't even remember making the OP. And that layout I did... that's atrocious...
Not that it helps much but here is a better set of layouts from when I revisited my .diy file a few months ago.
I also included the "modded gain range" values from the same source you found. Never had a chance to try it though since I gave my Guv'nor 1 with Deep Control away to a guy who used it on stage several times and loved it. (I need to get around to building the pedal again so I can use the spare deep board I have laying around in the "orphan circuits box.")
The layout on protoboard is not so bad! Is that verified?
Glad you like it. The layout in OP is verified but I can't see why the newer revisions wouldn't work. If any problems are found let me know and I'll update it.