Does anyone know how this works or how to make one? It sounds cools, and I just bought one, but I'm sure either Wolf, Newey or Sumgai can make one of these in their sleep. It's a rotary mid-shaper. Take a look:
I haven't seen anybody talk about that exact circuit. Doesn't really look to be inductor based, but it's hard to say. When you get yours you'll take some pics, maybe some meter readings, and we'll see what we can't deduce.
This page says that instead of varying the resistance before the cap, it changed cap values. That's pretty easy to do. Where it starts to get expensive is mil-spec rotary switches and smd caps which are not expensive themselves but take special tools to install.
It does seem like a device for switching in different cap values, and it talks about having 16 positions. Standard rotary switches can have 12 positions, so one of those could be the basis of an inexpensive home made version.
Lets say 1st position is off - no cap. A guitar and 10' cord, with some self capacitance of the pups has a capacitance of about 600pF. So the object would be to add extra caps to give a series of equal-ratio increments up to the max value of 22nF
So with 12 positions, a series of extra caps to be switched in might be:
Each increment adds about 40 to 50% to the total, including 600pF self capacitance. At each step, the resonance and treble roll off will change by about 20 to 25%, or about 1/3 octave.
This would involve 11 capacitors all connected to ground at one end, selected by the switch. Another way, maybe easier to make, would be to have the caps in a series chain, the more caps in series selected, the smaller the value. For the same overall results, a suitable range would be: