How to Solve the Treble-Bleed/Fuzz Problem

To put the problem as simply as possible: The input impedance of a classic fuzz or booster design is very low, usually lower than 20kohms. Together with the pickup inductance (usually 2.5 H up to 8 H) it creates a low-pass filter, a happy accident with an ear-friendly result. When a fuzz pedal, for instance, receives a kind of neutral carrier signal, it results in good, harmonic-sounding overtone content. But this balance is very fragile, so if the fuzz receives an input signal containing a lot of high end (caused by a treble-bleed network, buffer, active guitar signal, etc.), that balance is disturbed. A lot of intermodulation distortion will be generated between the overtones of the input signal and the generated overtones of the distorted signal. Sum tones and difference tones will be present, which sound dissonant and not very pleasant. So, we can say that the natural filtering of the guitar signal at the input of the pedal is essential for the typical, well-known fuzz tone.