Diagram of normal sinus rhythm as seen on ECG. In atrial fibrillation the P waves, which represent depolarization of the top of the heart, are absent.
The wah-wah pedal is based on a simple concept but its effect is far more dramatic. Using a powerful filter to sweep through a broad frequency spectrum, the wah pedal boosts and exaggerates specific tones. Creating sounds that range from thick, flubbery bass to scratchy, stinging treble.
Guitar amplifiers and electronic keyboards may have switch pedals for turning built-in reverb and distortion effects on and off; the pedals contain only a switch, with the circuitry for the effect being housed in the amplifier chassis.