Can you add a tone knob to the original EVH model by replaceing the one knob with a push pull knob ( vol. / tone ) or with one of the new Fender knobs with the button on the top?
Anyone got this figured out? Thanks guys.
Adding a tone control is pretty straight forward. Essentially you take the input from the pickups to the volume pot and run a capacitor from there to the middle lug of the tone pot. Then wire one of the other lugs of the tone pot to ground like this: http://www.seymourduncan.com/website/support/schematics/2hb_1vol_1tone_3way.html
I don't have an EVH, so you'll want to be sure that the new volume & tone pot have the same resistance (probably 500k) and pick the size of the cap (probably 0.047 microfarads).
One last thing to keep in mind- adding a tone pot that wasn't there before will add a little more load to the pickups and will affect the sound slightly (if there's not a resistor in place where a tone pot would normally go). Even with the tone pot wide open, you might lose a little bit of high-end (depends on the pickups).
Might not be a bad idea to solder in the cap & a regular pot first to see if you like it. Then if you're happy you can rip out the volume pot and put in a dual concentric pot. (And if you're not, you haven't really changed anything.)