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Stupidly Wonderful Tone Control 3A Simple Passive Tone Control for Effects Pedals
A closer look reveals that it does not have the "constant volume" design philosophy of the SWTC, but the volume loss is small and the tone network has some interesting characteristics nonetheless.
When the Tone pot is clockwise, the effect of the 100n capacitor is reduced and most of the rolloff is a first order R/C from the 4.7k resistor and the 47n capacitor. As the tone control is rotated counterclockwise, the 100n is brought into play until you finally have a second order R/C with the 10k of the pot and the 100n capacitor forming the second pole.
This tone filter is very heavy with most of the high frequencies rolled off.
As you can see, both capacitors have been reduced in value to open up the mids of the filter more than in the original. The 22n value may be too small, depending on the circuit in which the control is used, and the value may be increased to 33n or 47n as needed. This tone control is best used with circuits that have a lot of high frequency content that needs to be tamed, such as a fuzz (overdrive/distortion). It can only reduce high frequency content but is calaculated to have a response roughly similar to the speakers of an amp.
Add this to a dual mini-booster, or Rat clone, and have some smooth distortion sounds!
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I saw this tone control design in an old magazine from the early 1970s, and on first glance, it resembles the 
A simple change to the values of the capacitors will yield a response with more high end, which is a better response for modern rock styles.
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