Quick Tone Control/Filter Question

[erick4x4]

Can anyone tell me how the 2 parts in a simple tone control filter work. Like the one on a guitar, or that a lot of people stick on the end of the circuit. Just a Tone pot -> cap -> ground.

How does the cap and pot values affect this? It seems like the larger pot would shunt more frequencies to the ground, but what about the pot value?

Thanks!

[momiel]

The frequency at wich a filter start to cut high(or low) is given by this formula:
f=1/(2piRC). C is the capacitance (in Farads, not micro!) and R is the resistance (in Ohm). remember any resistor in series with the pot....

[GibsonGM]

Read up on "capacitive reactance"...Google for it.  Capacitors pass high frequencies easier than they do low...at DC, freq=0, they don't pass anything at all. They are "frequency dependent resistors", actually.  The relationship between resistance and capacitance, as momiel pointed out, is just that formula above.  There's more to it, that is gettable on the net, for more complex details of the whole thing.

So, the higher value of the pot in a guitar tone control is "slowing down" how much the cap can dump to ground - it passes it on thru the circuit instead of to ground, and your tone is "normal".    Lower the value of resistance in series with the cap by turning the tone control, and more of the highs 'picked up' by the cap will shunt to ground...make sense?  It's like plumbing and valves...