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.
The expression pedal is clearly visible directly above the pedalboard. An expression pedal is an important control found on many musical instruments including organs, electronic keyboards and pedal steel guitar. The musician uses the pedal to control different aspects of the sound, commonly volume. stand alone expression pedal used with electronic keyboards, amplifiers, and effects is usually a smaller pedal made of metal or plastic that can be placed on the floor and then connected to the device with an instrument cable.