DIYguitarist.com

[Paul Marossy]

I recently did some of the the mods to a Big Muff Pi at premierguitar.com directly for Brian Wampler. I did the basic mods plus the ones to make it "creamier" and I also did the dual tone control mod.

Now I haven't played a Big Muff Pi before this morning, and I was playing it this morning and I think that it is a pretty versatile pedal with all of these mods done to it. I made a quick soundclip of it to demonstrate how tweaking the controls will change how it sounds. The guitar I am using is my SpankenStrat with only the bridge pickup, which is a DiMarzio FRED. The tone controls are very interactive and yield a wide range of sounds.

Doing the mods was a real pain in the rear, however. The first thing that I found is that tracks on the PCB will literally melt away if you keep the desoldering braid on one spot too long. I've never seen a PCB like it before - it's like the tracks are actually made from tin, and not from copper. I found that it's better to hold the soldering iron to the component being removed on the solder side of the PCB and pry the part off from the opposite side, and then quickly use some desoldering braid to clean up the holes. The other thing to keep an eye on is to not break any of the very fragile wires while doing the mods.

To do the dual tone control mods, it requires the relocation of the status LED and the enlargement of the hole where the LED was mounted. This allows for the addition of the second tone control. See the picture below:



Also, it's a good idea to mark where each wire of the ribbon cable goes in case any of these wires break while doing the mods. It's also very helpful to do this when you do the dual tone control mod as you'll need to reconnect three of the wires in the ribbon cable.



Just a sidenote: The owner of the pedal had replaced the input & output jacks for some reason, and I had to find a better way of supporting the PCB rather than the foam and electrical tape that was used - another thing I had to fix. I kept some of the foam in there to prevent anything from shorting out, and for supporting the end of the PCB. It took about 3-4 hours to repair and mod it.
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"When the legends die, the dreams end. And when the dreams end, there is no more greatness."

[faction6]

I did this mod earlier today and I cannot get it to pass a signal when engaged. When bypassed its fine, of course. I had already done the emitter mod to the Big muff so I was wondering if that would make a difference? I would not think so but.... yeah I know, faction6....what loser. HA.

[Paul Marossy]

Check for cold solder joints and/or any broken wires. I find that the wires don't really take solder very well.

Also, you have to be very careful when doing the mods or else the "tracks" on the PCB will literally melt away and then something gets taken out of the circuit. That PCB is very strange, it's like solder tracks on a substrate instead of copper.
_________________
_/\/\/\_PJM_/\/\/\_
www.MySpace.com/j201jams
www.DIYguitarist.com

"When the legends die, the dreams end. And when the dreams end, there is no more greatness."

[faction6]

Got it. Yup bad trace. Thanks

[Paul Marossy]