Proto Pedal Example: Analog Equalizer Project
Contributors:
Byron J.
Byron J. 
The Circuit
The Challenge - to devise an analog circuit that makes a usable guitar pedal and can be built entirely from parts in the SparkFun catalog.
The Result - an analog equalizer based on Fred Forssell's equalizer white paper. The result is a good sounding and flexible pedal design, featuring bell-shaped bass and treble controls. The low frequency is centered on 100 Hz, and the high frequency is centered on 3.2 kHz. Each band offers about 10 dB cut and boost.
Frequency Response Graph
(click to enlarge).
(click to enlarge).
The filters are also easily tuned to other frequencies and modified for shelving response.
Dual Band EQ Schematic
(click to enlarge).
(click to enlarge).