While the sound of the acoustic guitar depends on the vibration of its body and the air surrounding it, the sound of the electric guitar depends largely on the signal transmitted from the pickups. A variety of effect devices or circuits can further change and process the tone of the signal while it travels to the amplifier. Likewise, amplifiers and speakers add even more color to the final sound.
Pickups of the electric guitar
Traditional electric guitars usually have two or three magnetic pickups. Identical pickups create different tones depending on their position between the neck and the bridge. Bridge pickups, on one hand, produce bright or treble-like timbres, and neck pickups are smoother and more bass-heavy. The type of pickup also affects the sound. People often describe the sound of dual-coil pickups as warm and thick, and single-coil pickups as bright and clear. If there is more than one pickup, a switch alternates between the outputs of individual pickups or a combination of them. For this, two-pickup guitars have three-way switches, and three-pickup guitars have five-way switches.
The final stages of the onboard sound-shaping circuit are the volume control potentiometer and tone control. The latter is a low-pass filter that “rolls off” the treble frequencies. Individual volume controls for different pickups also exist on some guitars, providing further possibilities to adjust the sound.
Pedal stompboxes and amplifier systems
In the 1960s, the tonal range of the electric guitar was further developed with the inclusion of effect units across the signal before the amplifier. These units have been created in a number of formats, the most common of which is the “pedal stompbox” and the rackmount unit.
A small metal or plastic box contains the circuitry of the stompbox. One or more switches, often pressed with the foot, activate it. For this reason, the stompbox often rests on the floor in front of the player. The rackmount effect units may use an electronic circuit almost identical to the stompbox effect. However, a standard equipment rack houses the electronics in this case.
The solid-body electric guitar does not create enough sound for the listener to hear it in a performance setting unless it is electronically amplified — plugged to an amplifier, a mixing console, or PA. Guitar amplifier designs use a different approach than sound reinforcement amplifiers and home hi-fi stereo systems. By design, the latter aim to faithfully replicate the source signal without the introduction of tonal coloring or distortion. On the other hand, guitar amplifiers purposefully color the signal, which can even define a trademark sound for different manufacturers.