Hi everybody!
After several modifications to my wah pedal (dunlop GC-95) I decided to add a external "Q" control. I bouth a 100K linear pot and tried to wire in place of the original 33k resistor. The problem is that I can't make it work, all I get is either the original wah sound through most of the pot's sweep or no wah at all when the pot hits the other end. I can't get it to sweep from 0 to 100K as I thought it would happen. I know the pot is not damaged because the multimeter reads the sweep (0 to 100k)just fine before I hook up the pot to the pcb board, then all I get is either 0 or 32.7k. Here's how I hooked up the potentiometer.
Terminal one - connected to PCB (where 33k resistor was)
Terminal two- connected to PCB (where 33k resistor was)
Terminal three- jumper to Terminal two
I know I'm supposed to run a resistor in series with the potentioter to keep the minimum value higher then zero but even without the resistor, the pot should still give me the whole range of resistence values right?
What am I doing wrong?

Thanks a lot!

I'm sorry, cannot help without the schematic, can you get it or post it? But yes it normally can be done.

The 33K resistor is not the Q component in the circuit--when you change it, you change the vocal characteristic of the effect, not the Q. The critical Q component is the .01uF capacitor connected to the inductor.

I would suggest a rotary switch with the common connected to 1 side of the .01uF cap and each switch position thru various capacitors all connected to the other side of the .01uF cap. Moving the Q higher than stock would not do much for a guitar, but I have changed the cap to .033uF and it kicks butt even on low B 7-strings. Any lower Q is not that usable for guitar. I would suggest trying capacitor values of .02uF, .015uF, .01uF and .005uF on a 5-way switch with one OFF position for stock sound. These are polystyrene caps and I recommend these caps from Mouser here (very bottom left): http://www.mouser.com/catalog/633/818.pdf

Since they only go up to .01uF, you will have to put 2 caps in parallel to get the .02uF and .015uF values.

Another thing you may want to do is stack another one of these caps in parallel with the other stock .01uF. This lowers the stock high-pass frequency (about 95hz--ouch) on the input coupling and allows more of the bass frequencies into the wah circuit. If you have the stock 68K input resistor, the best value is .005uF. If you replaced the 68K input resistor with a lower value for more volume, use the .0068uF. Any larger values here will put the -3db point below 60HZ. This is useless for the guitar and only adds subsonic flubbiness and the possibility of amplifying 60HZ signals that are everywhere. Use those polystyrene caps, above.

The 33k resistor is the "Q" resistor. According to R.G. Keen in "The Technology of Wah Pedals"
"
This resistor is the primary determiner of the Q, or sharpness of the bandpass/resonance effect of the filter Values lower than 33K make the filter less sharp, reducing the quality of the wah effect. Values up to 100K contribute to sharper, peakier, more resonant tones. If it gets too sharp, the wah effect can be lost because it may not hit harmonics to emphasize."