|A very simple version of the varitone
can be found on many models of Gretsch guitars. In lieu of a tone
knob (for whatever reason!), you will find that there is a second toggle
right next to the pickup selector switch that looks just like a clone of
Incidentally, most people find these to be largely worthless, with the two altered signals being described as "muddy" and "muddier," but there are certainly some applications... and, naturally, there's no reason you can't modify it to make it more useful. More about that in a bit.
This is a three-way switch, just like the pickup selector, and it toggles between two capacitors, with a bypass in the middle.
The values of these two capacitors are (at least in my G1910 Double Cutaway; I didn't check my 6120 since those are harder to access, but I've also seen schematics with these same values):22,000 pF = 0.022 µF = "muddy" = similar to many jazz guitar tonesThe middle lug connects to the volume potentiometer just as any tone pot would (i.e., usually to the lug going to the output, but it could also be the middle lug on the three-way pickup selector). Note that (in spite of the implication of the picture) the switch in this case has to be an On/Off/On switch. The middle position of a conventional 3-way switch would be "both" rather than "no" capacitors... just as the switch on your Les Paul selects both pickups in the middle position. Keep that in mind if you're building your own tone switch.
47,000 pF = 0.047 µF = "muddier" = like the tone knob turned to zero
Personally, I think this mod is a trade-off. On the one hand you can literally "switch" your tone to something warmer with the flick of a your wrist, but on the other hand, you lost the subtlety of a tone knob.