Original Marshall Guv'Nor - Mod for more bass

[craggsy]

Hi there!

I bought an original Marshall Guv'Nor overdrive pedal off eBay for £10 (about $20) and was an absolute steal! 

It's a good pedal but could be better. I was wanting to change a few caps for more bass response and wondering if you could give me pointers on which caps to change.

I'll be working off the schematic at GGG (http://www.generalguitargadgets.com/diagrams/guvnor_sc.gif). I thought about changing the cap c5 which I think is the low pass filter to 1.0uF however upon checking the circuit there's a resister in its place!?!.

So any advice would be greatly appreciated.

Cheers

PS Should I keep the pedal standard as they are becoming abit of a rarity and use the clone circuit which I previously ordered from GGG?


PS Should I keep the pedal standard as they are becomming abit of a rarety and use the clone circuit which i priously ordered from GGG?

[moosapotamus]

The usual suspects for more bass... increase cap values, input (C5), coupling caps (C3, C9), output cap, etc... C14 makes a low pass filter. Increase for more bass.

Don't know for sure how it would sound, but you could try adapting Jack Orman's TS9 fat mod at IC1a.
http://www.muzique.com/lab/fatt.htm

No doubt, the tone stack could be tweaked for more bass, too. I'm not sure exactly how. Maybe someone else could comment on that.

If you're going to try a bunch of different things like those above, and you are already getting a PCB from GGG anyway, I would avoid butchering your original.

Have fun!
~ Charlie

[craggsy]

Thats for the information there moosapotamus, ill certainly look into it.

I think I will use the board I have from GGG so to experiment and not to bugger the original!

If anyone has any suggestions on making the EQ more bass friendly I would be grateful!

Thanks again for the advice

[mojotron]

I did so many mods to mine that I don't know if this first mod did the trick or not, you may need to do both:

1) I changed C1 to .22uF and used a 2k pot for a "depth" control - but you might be happy with something more or less than .22uF.

The pot makes this a lot more flexible by dialing in the "fine adjust" for frequencies to apply the gain to and the cap (C1) sets the "knee" in the LPF made up of C1 and R1. So the cap determines more of the "coarse adjust" for the LPF making the end result sound like the cap controls the amount of gain you want to get from the first gain stage and the pot controlling the low-end roll off of that gain.

2) I doubled the size of the coupling caps C3, C4 and C9 - but you might not want to go that far.

3) Another thing I did was to tie the wiper of VR1 to C3 - this takes the gain to a whole different level - you won't even need those diodes/LEDs 

[craggsy]

Thanks both again for your suggestions,

I'm going to build it on the board I have from GGG, have abit experiment and see what happens!

mojotron, that depth control sounds interesting, something ill definitely try.

Cheers
Craggsy

[mojotron]

Thanks both again for your suggestions,

I'm going to build it on the board I have from GGG, have abit experiment and see what happens!

mojotron, that depth control sounds interesting, something ill definitely try.

Cheers
Craggsy

Thanks, I do the same thing (and a few other things) on my TS9/Fulldrive "modded to death clone" I call "The Id" that I'm shamelessly promoting on my WWW site (email me if anyone wants these mods - I have not given them clever names nor claim that I came up with the ideas... they all came from threads here and elsewhere). When I got to buying and trying different TS clones I sort of boiled the change that defined a couple of great sounds to 5 or so resistor settings in 1st stage feedback loops like on the Guv'nor and TS - all variants of the "fat mod" suggested by moosapotamus - so I use a pot where Jack suggests some resistor settings.