Big Muff "Rams Head" Fuzz Pedal 

June 12, 2014

Modification to add a DC Power Input Jack 

In this installment, we were asked to put a DC Power Jack on the pedal for use with external power supplies. We are going to wire it to the Roland Tip Negative standard Polarity. 

  While we are in surgery, we will also install a new Battery Clip, and replace the Guitar Input Jack with a new jack with a switch for turning the Pedal on and off. 

Items Needed
DC Jack
Battery Clip
Input jack – Switching type

First we remove the stock On/Off slide switch. This hole will be filed out to accommodate the new DC Input jack. We used a Metal jack that takes a plug size 2.1 X 5.5 mm, and there is as witch to the sleeve. This switch contact is used to connect to the battery when there is no power supply used. 

If the external power source is not plugged in, the battery is connected. We mount the jack in the chassis and wire it as shown in the photo.Next we wire the new Battery Clip into the pedal so that we can still use battery power if we want. One lead is connected to the switch terminal on the DC input jack and the other connects to the PC Board. We will replace the Guitar Input jack to substitute for the On/Off Switch we removed. 

Mount the Jack and wire it as seen in the photos. 

There are two more mods that I would recommend. This pedal was not made with a True Bypass Switch, and it would not be difficult to change it. This Pedal has a boat load of Gain to get the Fuzz Tone. Therefore when it is powered by an external power supply, that power supply must be well regulated, that is a Noise Free Power Source. I tried three or four common Wall Wart Power Supplies, and they all had some noise getting to the output. So, we can add some regulation and some extra filtering to get back our Battery like power source.

That’s it! Happy Fuzzing!

Battery clip and DC input Jack

Battery, the arrows drawn on the board point to the positive battery leads footswitch 

the switching jack installed

close up of the switching jack