From
www.kinman.com:
VOLUME Control control: (Treble Bypass filter -or- treble bleed filter)
It is simply a .0012uF (1.2nF) 630* volt Polyester capacitor in series with a 130K Ohm resistor (1/4 watt) that is wired across the two hot terminals of the volume pot (*any voltage cap will work fine but 630 volt caps have thick wires that are easy to work with). Rule of thumb is the *amount* of brightness that is gained is determined by the resistor's value (less Ohms = more brights) but the frequencies that are present is determined by the Cap value (lower the value the higher the frequencies, the higher the value the lower the frequencies).
By the way, this design works better than a 'capacitor' only -or- the parallel 'resistor/capacitor' design that some makers fit to their guitars
I use this with my Duncans in my PRS McCarty and it works great!