Mad Professor Snow White Auto Wah Effects Pedal w/ Power Supply Sensitivity: Sets the filter trigger lvel, tune this carefully to fit your guitar/bass output and your playing touch. You can further change the sensitivity from your guitar volume knob while playing. Bias: Controls the fitler resonance frequency. When sensitivity is turned fully off the bias can be used as a sweepable fitler. Resonance: Controls the sharpness or Q-Factor of the filter Decay: Controls how fast the filter frequency falls back to resting point (that is set with the Bias control) This can be set fast (CW) so you get the wah effect on every note or slow for more traditional auto wah sound.