The science behind how an electric guitar produces that iconic loud sound!
As opposed to an acoustic equivalent, which uses a hollow body to amplify the vibrating strings, a solid-body electric guitar requires a set of pickups to project the sound.
It uses a principle of electromagnetic induction to translate the movement of metal strings into a very small electric current within a set of pickups. These tightly wound magnetic coils are positioned directly under the area where the player strums and usually contain a set of six pole pieces that sit directly below each string. When the string is plucked it induces a voltage fluctuation inside the pickup, which is then channelled out of the instrument down a lead and into an amplifier. The wattage of the guitar amp largely defines the volume with big live acts using powerful 16 speaker stacks to achieve maximum loudness.
Players also boost the raw guitar signal with effects units or foot pedals that apply layers of distortion for achieving that distinctive crunching rock sound.
We know that the vibrating steel strings generate an electric current within the pickups, but the frequency of this current is proportional to certain characteristics of the string itself.
The wavelength of the oscillations change as the strings are plucked at various frets, and the player uses tension with the fretting hand to shorten the length of the string at each interval of the fret board. This changes the vibration pitch passing above the pickup to create the notes needed to form the chords. A thicker ‘gauge’ of string tends to offer a louder output and heavier tones, while factors such as how the string has been wound also influence the final sound.