ProCo Rat - Mod Idea

[amonte]

I'm getting read to make some changes to my old RAT 2 pedal.  I've done some research on the web and come across a lot of the standard mods.  I've also bought Jack Orman's E-Book on modding the RAT (a great read!) and I have a pretty good idea of what I am going to do.

One of the limitations of modding the RAT 2 is the rather smallish enclosure.  While there is room to add a few switches without it looking to odd, adding a fourth knob (which I will need to do the Ruetz mod) would probably require drilling the sides of the enclosure.

So I got to thinking about making the Ruetz knob the Filter knob and then using a dual gang pot for the drive control - using the second half of the pot to roll off the highs via a low-pass filter - so there would be more treble at the lowest gain settings and less as the drive knob is turned.  To add a little more flexibility, I was planning on using a three-way toggle switch to flip between three different capacitors in the low-pass filter - kind of a dark-bright-normal switch. 

I guess my concern is that this sounds great in theory but won't work as well when it is executed.  I suppose I would need to have a "ceiling" on the high and low ends of the second half of the dual gang pot to prevent it from getting too bright or too muddy.  I also gave some thought to using the dual gang pot on the fourth knob (the Ruetz mod) and rolling the highs off there. 

So what do you guys think?  Worth trying on the breadboard?

[the recluse]

I didn't have any luck finding the part on mouser, but if you could find a stacked concentric pot (as on the Fender Nashville Power Tele) you could possibly try that. 

Edit: Actually, there is some on Ebay selling a lot of 11 100K audio taper dual concentric pots  Item number: 140122904277

[zarathustra]

You can fit two 16mm pots in there without having to drill the sides. Put them toward the "back" end of the pedal, where the jacks and DC input are. Then drill through that (much thinner) part of the enclosure.

[amonte]

I know that Hoffman Amps sells different values - not sure if they have a 100K dual gang.  I know they sell a 1M dual gang.

I actually have a couple of those 100K "stereo controls" from radio shack which appear to just be dual gang pots with an extra lug on the back...

[Processaurus]

You may want to try the ruetz mod (changing the pre-emphasis) on a breadboard before contemplating installing it as an external knob, its honestly not a night and day difference.  I did mine as a trimpot inside, just found a spot I liked, and left it.  The filter has been a much more useful external control, at least as far as getting a good sound with different amps. 

either that or maybe use a 3 position toggle switch for 3 pre-emphasis settings rather than a knob.  More consistency, and 3 settings would cover what is already a subtle change in the rat sound. 

The minimum gain mod is very good, it makes it so you can find the touchy setting where its almost clean but is a tiny bit ratty, instantly, by just turning the gain down all the way.