This is a handy calculator you can easily download:
http://www.duncanamps.com/tsc/ (http://www.duncanamps.com/tsc/)
Just input and play with resistor and cap values and move the treble, mid and bass sliders to see a nice graph of your frequency response. Very handy if you are modding your tone stack on your amp. Perfect for geeks like me. :P
(http://www.duncanamps.com/tsc/tsc_ani.gif)