Sorry for the absence. I've been busy actually making things in analog life. Recently I've noticed a bunch of online guitar folks talking about the weird switch Gibson came out with in the late 50's. The original idea wasn't around all that long, so perhaps that's why it's misunderstood. It's not a simple capacitor switch that simply cuts treble at different values. People do make those, and often claim it's a varitone. It's not. It's simply a variable low pass filter switch. The varitone is a variable notch filter, allowing you to cut different frequencies (often mids) across the spectrum using a magnetic inductor. Lot's of great info and discussion can be found here: https://guitarnuts2
It can really give you unique and cool sounds from an era that people missed out on. I think because people didn't really understand what it was doing, it got a bad reputation. People often tore them out. I remember being 17 in a guitar store playing a 1960s 335 and asking the owner what the giant switch was. He said "the worst idea Gibson ever came up with". Well, history showed it can always get worse. Guys like BB King and Freddie King loved them. Go back and listen to some of those performances. I'm convinced they used the positions 2 and 3 a lot. This video probably gives the best examples I've seen of the positions.
Last year I thought I'd take a swing at my own recipe for a varitone on my flying V. I wasn't using the single standard tone knob much, so it was my perfect candidate for a varitone. I wanted positions 2 and 3 and maybe 4, but towards the end of the switch, things sounded trashy and super lo-fi with very little bass. Very cool if you need that sound. I do like to cut treble live, to get a nice sustaining (non-squealing) feedback. So, I opted to add a standard cap to ground for that at position 2. Then I moved every other position one down. It just makes more sense for me playing live. I need to hit the treble cut faster than the other positions that I might stay on longer for a song.
So let's look at the updated schematic:
Some 10 meg resistors from the other side's center lug to each position lug to prevent popping sounds when switching. Then some caps to an inductor. In this case I used an easy to find audio transformer (TY-250) rated at 10.29 henrys and 20Hz to 20kHz.. Input to leg 2 and out to ground off leg 4. Because the henrys are at a different rating than the original Gibson one, I had to recalculate the values to work with my transformer.
So we get the following results:
Position 1 = Bypass all tone control
Position 2 = Treble cut (you can tweak the amount by value)
Position 3 = Slight scooped mids sound
Position 4 = More scooped upper mids
Position 5 = Thin bright sound with bass cut
Position 6 = Trashy lo-fi transistor radio tone
I find this works for me in my single tone knob guitar, but you can experiment with your own values within the ballpark of these to find your own sounds that work for you! 
