How to add/mod a Footswitch jack to a Mark I?

[jimkeaney]

I understand that a Footswitch (to boost channel 1) was a factory option on the Mark 1’s. I would like to add this to my Mark 1 head. Does anyone have experience/instructions on how exactly to implement this mod? I have to imagine it’s pretty straight forward and there’s already a blank hole in the rear of the chassis for it. Any info/guidance is appreciated. Thanks

 

[jimkeaney]

Thanks to some detailed photos of other user's Mark 1's on this board, I figured out the Footswitch Boost mod just by looking at it. It's about as simple as I had hoped. At the back of the first Push-Pull Potentiometer (Gain Knob #1/Boost) there is a resistor strapped across the two pins. If you solder a Tip/Sleeve jack (respectively) to those same 2 pins, it's essentially bypassing the resistor when you close the circuit with the foot switch.

 

[mark1406]

That mod is normally already wired into the amp. On my old Mark 1 amp there was a jack in the middle of the chassis, I just needed to get a cable and switch.

The EQ changes significantly. I liked the gain boost but I didn’t like the change in EQ. There are other ways to get more gain from a Mark 1.

Regards

Mark