Is there a good source on the web (maybe you) that could give me some wiring diagrams and capacitor/resistor values to install across volume controls to minimize loss of highs? I assume this condition is due to impedance loading on the pickup by the volume control when it is turned down. This almost always happens on my humbucker-equipped guitars.

I tried a .o1 mf cap - it did minimize the loss of highs, but also took alot of the other frequencies ("beef") out of the sound. A friend of mine told me to use a cap/resistor combo, but I'm having a hard time finding the cap resist. values. Would values vary depending on pickup ohm rating (say an early 70's number-stickered Gibson, vs. a SD Jeff Beck humbucker)?

>> Good question, and unfortunately one that doesn't have a single correct answer.

The values to use depend on just about everything - the impedance of your pickups, the value of your volume pot (and the actual reduced levels you want to use), the length and quality of your guitar lead, and the impedance of the amp or effect you plug into.

So the way to work it out is to experiment. Usually you will want a resistor in series with a capacitor connected accross the volume pot "hot" and wiper connections. The resistor would typically be a value between zero (ie no resistor) and about 270K, while typical capacitor values would be from 100pF to about 2.7nF (ie .0027uF).

Larger capacitor values have more effect on high-mids in addition to the highs. Larger resistor values reduce the overall effect of the treble bleed circuit. Maybe a starting point is 47K and 1nF.