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.
To preserve the clarity of the tone, it is most common to put compression, wah and overdrive pedals at the start of the chain, modulation (chorus, flanger, phase shifter) in the middle, and time-based units (delay, echo, reverb) at the end.