Tuesday, 5 March 2013

Marshall Guv'nor mods

The marshall Guv'nor was the first pedal I ever bought. And to be perfectly fair it is a very nice overdrive/distortion. I stumbled upon book, made by Brian Wampler, with a lot like I mean  lot of modifications to practically any pedal. Luckly it had the guv'nor on the list. One the the suggested mods are diode changing. The diodes that are originaly in there are red LEDs. Wampler suggested replacing them with 1N4001, the ones I used in the Distortion plus build(see previous posts). Another cool thing about this mod is that it makes the clipping section asymmetrical. There is two types of clipping symmetrical and asymmetrical:

This is a pretty good diagram showing the different kinds of diode clipping. Symmetrical has two diodes in parallel and asymmetrical has 1 diode on one side and two in series on the other side.

Anyways, this mod book says that this mod makes the clipping more responsive to pick attack, what the stock guv'nor lacked in. 

Switching diodes is a very easy way to modify any of your overdrive/distortion pedals that include a diode clipping section. This post will go through the desoldering process and replacing of the diodes with step by step instructions. 

Marshall GUV'NOR Plus
 Between my MXR Distortion Plus build (in previous posts) and now, I've gotten a new soldering iron. It's got a controllable wattage knob, not necessary but nice. A huge improvement from my last soldering iron.
Once you have opened up the back of your pedal and spotted the diodes you want to replace, the next step us to desolder. Before you even touch the soldering iron, make sure that your not replacing the wrong diode. Thats why I like using the mod book, it has a visual of the positioning. What I used to desolder is desoldering braid. I know desoldering pumps are a lot more effective, but it wasn't working for me for some reason. So I went back to basics. Anyway, it work out for me very well. If you want to learn how to use soldering braid I'm sure there are many sites on the internet and youtube for that.
 To be honest I am a little disappointed in the pump, but the braid is there for me
Make sure when you do apply your soldering iron you don't overheat the tracks. If you are able to see through the wholes / be able to fit the component through, you are ready for the next step
For the diodes, I am replacing them with 1N4001. The first one is just the single diode. I used the vertical diode technique o fit it in the right holes. Before you solder it in, make sure it's facing the right way. The line on the diode is facing the same way as the line on the schematic is facing. 
You might be able to see the schematic symbol on the PCB in this picture. But it will most likely be there, so put you diodes in the right way
The next diode I need to take out is replaced with two diodes in series. I good technique for soldering these together is bending one in a circle and putting the other one through the hole. This makes for easy soldering. Helping hand really help to hold the diodes in place.
 Make sure the diodes are facing the same way, like the picture below
 Because the holes were origonaly for an LED, I did need to be the diodes in a fancy way. Bending it this way really worked for me. You can bend it in any way, but just make sure the leads aren't touching any other components.
 What I like about this bend, it has a low profile so the excessive amount of wire in this pedal doesn't put pressure on the diodes.
Once everything is in position all you need to do is solder it in. PCB's have a very densely packed board so be extra carful about soldering.

I didn't have a lot of time to test out this mod, but from what I heard and played, it did make it more pick responsive, like the book said. I would say that this is a success

If you have any comments or question please leave them in the comment section below


  1. Heya. I've done the mod, so I think I should tell you guys how's the result.

    I always turn it on whenever I want to rock out the audience. More growly overdrive sound, more responsive pick attack. Couldn't be happier!

    The only thing that makes me unhappy is the volume drop. I turn the volume knob all the way up and the pedal is good to go. I wish there's another solution to fix this problem.

    If you have this pedal, I encourage you to DO this mod. I've tried the C22 mod too, but I don't like it very much because the sound become very thin. I put the C22 back and go back to his mod.

    Thanks for sharing the mod, Dimitri!

    1. 470pf rolls off too much highs, try replacing it with something like 100pf-220p.

  2. How, exactly, do you remove the C22? Cut it?

  3. You taste with germnanium diodes? 1N60 o 1N34?