Connect the BOSS parametric equalizer using the 1/4-inch phone plug patch cords. The guitar connects to the "input" jack on the right and the amplifier to the "output" jack on the left. Step on the foot switch until the LED on the top of the unit is lit.
Adjust low-frequency and high-frequency shelf filters by way of the stacked "presence/low" knobs on the left. The inner knob controls presence, or high frequencies, and the outer knob controls the low frequencies. Turning knobs counterclockwise reduces the parameter and turning them clockwise increases it.
Adjust middle and high frequencies by first selecting the frequency with the outer knob, then controlling the boost or cut using the inner knob. The "level" control knob on the right controls the mix of input signal and equalized signal. As with the other controls, turning the knob counterclockwise reduces the effect and turning it clockwise increases it.