Before you start changing your pedal, please keep in mind that you are trying to get the best sound for you. Make each change one by one, and listen to how it changes the sound of the wah, and see if you like it. When I work on a pedal I’m trying to balance the gain, treble, mids and bass. So each one sounds right to my ear. Don’t think that more of something is just better, you don’t need to “turn it up to eleven,” try and balance the tone to your taste. I have found these values are a good starting point and are by no means the last word on what may or may not produce the “perfect tone” for you, but simply a way to start listening.
It is also easy to take a stock wah pedal and turn it into a mess by altering the values. Please go slowly and keep track of what you are doing in case you need to go back to the beginning.
These resistors mods are optional. I do recommend changing the 68K resistor if you are adding a true bypass switch, this helps you retain a more even volume when the pedal is switched between off and on.
Input Mod:
This is shown as the stock 68K resistor. I suggest this mod for anyone who is installing the True Bypass switch. Install the 57K resistor in place here. This will help retain a more even volume between the on and off settings.
The Vocal Mod:
This is shown as the stock 33K resistor. I suggest the 100K resistor in this spot, you can alternately use the 68K resistor, and use the one you have taken out in place of the 57K. You can experiment with ranges from 33K-100K.
Bass Mod:
The stock resistor is 390 ohm some pedals have a 470 ohm or 510 ohm.
Install the 330 ohm resistor in this spot.
By lowering this value you increase the gain and lower frequencies.
Making it higher will make the pedal sound brighter.
Midrange:
The is the stock 1K5 resistor (1.5 K) replace this with the 2K resistor this will bring out the mids as well as create a more even transition to the lower frequencies.