Capacitor Value and Tone Question

[spacefuzz74]

When capacitor values are swapped to achieve more treble or bass in a circuit, you lower for more treble, and increase for more bass, correct?

For example, on the attached Fulltone layout, if i wanted to give the low end a boost, would i increase both cap values?  if so, why both...or, why only one?

[Ciaran Haslett]

That statement is true when we talk about coupling caps...caps that pass AC but block DC.  A common example is Input and Output caps.

Then there's filters.  High Pass, Low Pass, Band Pass etc.  Here's a handy online calculator for working out RC values for different kinds of filters.  Plug in some values and see how the cutoff frequency changes.  

Then look at the Fat Boost schematic, especially the tone pot.  Its a cap with a resistor to ground...a High Pass filter!  Plug in some values into the calculator and see how you can tailor that tone pot to your desired needs.

You will also notice that your guitar signal comes out of the JFET amplifier and through the 220n.  Its a coupling cap so if we increase it, we allow more bass frequencies to pass.