The Atlantic has a great piece on the mods and technologies that developed alongside the electric guitar in the later half of the 20th century, many of which emerged accidentally or through trial and error.
There’s an old joke in the technology industry: If a product has a problem, simply sell it as a feature. The electric-guitar-effects industry is no different. Music has often thrived on transforming faults into influential sound effects. Before professional studio production enabled granular tweaks in sound, standalone guitar effects emerged from deliberately converting hardware faults—often caused by the limitations of amplifiers—into positive features. By the end of the 1970s, it had become impossible to imagine how R&B, blues, and rock could have existed without these fortuitous mistakes.
In fact, the history of guitar-signal modification is one of happy accidents. Any “unmistakable” guitar sound isn’t just the product of a gifted musician, nor is it just the result of cultural context; it’s contingent on the combined work of transistors, speakers, magnets, signals, wires, and diodes.
Consider how many transformations take place during the production of sound from an electric guitar. The guitarist picks a string with a plastic plectrum, which produces vibrations that are picked up by coiled magnets directly positioned behind the strings, inducing an alternating current (hence the name “pick-ups”). The current’s signal is then transmitted through a wire lead, after which it’s amplified by either a vacuum tube or solid-state amplifier, and then reshaped into audible sound by a loudspeaker. Depending on the sound that a guitarist is seeking, he or she may place guitar effect pedals, or stompboxes, in between the pick-ups and the amplifiers. These small, intermediary devices further manipulate the guitar signal to produce a multitude of effects.