Bill's current filter is an LCR network, sized as a 1" cube, and can be a helpful device for multi-sound capabilities. It is an item Bill has promoted as a player and a designer since the 60's, and he's most famous for using it in the guitar he designed for Gibson back in the 70's -- the L6S
. It can simply take the place of the capacitor at the tone control or wired to a push-pull or on-off switch to maintain the standard tone control position while switching to the "Q-Tone".
Inductance - 1.8 Henry
Inductance - 3.0 Henry