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.

Perhaps the most famous of these sounds—or, at least, the most formative—is that of Dave Davies, the lead guitarist for The Kinks, who got bored of his Elpico amplifier in 1964 and decided to pierce its speaker cone with a razor blade. This effect, known as “clipping,” cuts off the audible waveform at the height of the amplifier’s limits (voltage, current, and thermal), thereby distorting the signal. Although Link Wray had been doing this since the late 1950s, Davies popularized guitar distortion in the first few moments of “You Really Got Me,” changing guitar music.

Artists have been converging on this sound for more than a decade before Davies used it. In 1951, “Rocket 88” by Ike Turner and the Kings of Rhythm took advantage of a distorted amplifier that had been damaged in transport. The same thing happened to the Johnny Burnette Trio in 1956, when Paul Burlison pulled out a vacuum tube from his amplifier after it fell off the top of the band’s car. He loved the sound so much he used it to record “The Train Kept a-rollin,” which inspired a whole raft of British musicians:

Most lo-fi amplifiers in the 40s and 50s produced unexpected distortion or overdrive tones at higher volumes. Guitarists quickly discovered that the Fender Tweed Champ (originally marketed to beginners as the Champion 800 in 1948) produced a distorted sound at high-volume levels thanks to the Champ’s low power output and simple circuitry. Many of the classic guitar solos in the 1950s were recorded through a Champ, which resembled a wide-panel TV cabinet covered in tweed cloth. Leo Fender even went so far as to manufacture the first 100-watt amplifiers for surf guitar pioneer Dick Dale, who had blown hundreds of Fender amps and speakers from regularly turning up the volume.

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The history of signal modification isn’t just one of pleasing the ear through unconventional methods. It works both ways: Guitar effects have modified their users, just as much as their users and engineers have modified their sound. New effects can change a guitarist’s playing ability completely, concealing their technique as well as embellishing it. U2’s The Edge, for example, is known for his restraint of technique by embedding different rhythms within delay settings.

Some effects, and the boxes that produced them, altered musical periods beyond recognition. The valve-driven Watkins Copicat, for example, will forever be associated with the sound of the late 1950s British music “beat” scene. Developed by Charlie Watkins in 1958, this odd machine supported a tape-recording mechanism that would record and play back any sound with varying lengths of delay in-between the replay heads. The device was critical to the rockabilly sound of the late 1950s, the “beat-group” sound of The Shadows, and the Liverpool Merseybeat scene of early 1960s (as well as the Birminghambeat, or Brumbeat scene). The sensation of hearing a guitar warble and wail to its own output encouraged guitarists to experiment with different styles of attack and vigor. For example, the noise that begins and ends the original 1962 recording of “Telstar” by the Tornados was made using the Copicat by creating a loop of echo and reverb effects. This produced what can best be described as some sort of space-echo/attack-helicopter noise.

Some effects produced dramatically weird sounds that were largely impossible to pull off. The peculiar 1948 DeArmond Trem-Trol (used extensively by rock-and-roll pioneer Bo Diddley) altered the volume of the guitar signal by exposing the connecting pin to a brass-and-glass canister half-filled with shaking, water-based electrolytic “Hydro-fluid.” The shaking—and often leaky—fluid washed over the pin and would bend the signal’s volume, causing an oscillating, watery tone. In the words of Chris Gray, one of its few remaining owners, “This is not a subtle effect—it adds all its personality to your sound whether you’re ready for it or not.”

Other notable effects include the tube-driven Leslie speaker series, which originally modified the sound of electric organs (such as the Hammond B3) until guitarists like George Harrison (and the Beatles more generally) began to use it for spacey chorus, tremolo, and phaser tones. The classic 60s model, the Leslie 122, was housed in a huge 41-inch wooden laminate casing and comprised of two motors (essentially two electromechanical horns) that had been rotated to create a Doppler-effect-based vibrato. These horns were, in turn, picked up by the dual speaker units. The Leslie 122 wasn’t even built to connect to a guitar, but bull-headed technicians fudged the electronics and made it work anyway. The laminate wood wasn’t just for aesthetics, either: It functioned as a partial enclosure, ensuring mellower tones, and different woods created different vibratos.

It obviously wasn’t ideal for guitarists to permanently damage their amplifiers for the benefit of experimental tone. Nor was it practical for them to drag immovably large objects on tours. Luckily, increasing experimentation in guitar sound modification collided with the widespread manufacture of electronic transistors in the early 1960s, which replaced vacuum tubes and integrated synthetic distortion in amplifiers. As the transistor revolutionized computing, it also dramatically simplified the production of guitar effects and amplifiers, allowing compact design and portability with little overheating.

The common design of a standalone stompbox is simple and, thus, hasn’t changed much: The guitar lead plugs into an input while a second lead carries the output to the amplifier. In between, a multitude of knobs, switches, and pedals modify the signal. To connect two or more boxes requires “jumper” leads, which chain the boxes together to complete a circuit of circuits, each one powered by a 9V battery. Typically, stompboxes are activated by “stomping” on an on/off bypass switch. This simple design enables tinkering: The exterior casing can be easily removed, exposing the interior for modification. To do so requires only a basic grasp of electronics, solder tools (or a solder-less breadboard circuit), and patience. Lots of patience.

After the introduction of electronic transistors in the 60s, engineers began to emulate these new and raw vacuum tube sounds with the new technology. They often used germanium transistors, which were not only cheap, but also had a sensitivity for generating bizarre fuzz tones, a quality that became a key ground for experimentation. The first mass-produced box was the Gibson Maestro FZ-1A Fuzz-Tone, which launched in 1962, right at the birth of British rock: The Fuzz-Tone was responsible for Keith Richard’s sound in 1965’s “(I Can’t Get No) Satisfaction,” transforming it from a mild Dylan-esque acoustic record into the Stone’s signature confrontational delivery.

Nashville studio engineer Glen Snoddy discovered the Fuzz-Tone sound when recording Marty Robbin’s 1960 hit “Don’t Worry About Me.” Allegedly an overloaded transformer blew in a Langevin tube module, transforming Grady Martin’s bass guitar into a distorted, heavy fuzz. Some put the event down to another case of amplifier malfunction. Either way, Martin continued to use the tone throughout 1961 while Snoddy transistorized the malfunctioning circuit through trial and error, and sold it onto Gibson in 1962.

This, in turn, led to the first stompbox-pedal-and-fuzz circuit used for recording purposes, designed by Orville “Red” Rhodes in 1961. It was never produced commercially and was built primarily to recreate Martin’s sound for Nokie Edwards (of The Ventures fame) and Billy Strange (who used it for Ann-Margaret’s 1961 hit “I Just Don’t Understand”).

Inspired by the Fuzz-Tone’s ability to add an aggressive swagger to any guitar melody, the mid-60s saw an explosion of copycat fuzz stompboxes. Most of the imitations were atrocious, but some became infamous. A few deliberately tried to combat the limitations of guitars themselves, like Gary Hurst’s 1965 Sola Sound Tone Bender MKI, which reused the three-transistor circuit of the Fuzz Tone. For the MKI, Hurst tweaked certain resistor values, which extended, or sustained, the guitar notes for longer. A two-transistor version of the tone bender (the MKI.5) morphed into Jimi Hendrix’s favorite stompbox, the simple and durable Arbiter Fuzz Face. The later model, the MKII, was at the heart of Jimmy Page’s secret sound in early Led Zeppelin recordings, When the Fuzz Face was released in 1966, it set a precedent for Hendrix imitators (“I Don’t Live Today” being the most frenetic extension of the Fuzz Face’s limits). With a keen ear for experimentation, Hendrix would often prefer the Fuzz Face’s tone when the battery was half-charged, in large part because germanium transistors fluctuate according to voltage. Guitarists would often have to wade through different batteries in order to find their own tone.

Eventually, silicon transistors replaced germanium ones, helping to combat the inconsistent sounds of the germanium version (each circuit varies, and they were often affected by hot temperatures). Silicon completely changed the distortion, making it brighter, edgier, and more aggressive, as exemplified by the famous Electro-Harmonix Big Muff. The later introduction of the integrated circuit provided even more stability. Digital emulators can now universalize effects in a standalone unit. Materials don’t lie, however; when compared to their analog ancestors, the digital units lack the unique wildness of the germanium effect.

The late 60s and 70s produced even more bizarre and berserk creations. The birth of Mayfield and Mullen’s VOX King Wah pedal sealed its place in guitar history during overbearingly long, Clapton-esque guitar solos. The 1978 Pro Co RAT, whose design was a re-imagining of the Arbiter Fuzz Face, arose partly from error: A botched resistor band created a harsher, clipped audio waveform. Its use has supported nearly all “alternative” rock genres in the last 30 years: 80s punk, American indie rock, Grunge (the RAT played a crucial part in Cobain’s quiet-loud-quiet-loud composition), not to mention Britpop and grindcore.

More recently, many boutique pedal manufacturers, such as the Z.Vex and Death by Audio series, have attempted to revive the analog strangeness of germanium transistors and diodes. Not bound by imitation, they continue to innovate with analog materials as if the technical innovations of the 70s and 80s had never happened. The mid-90s Z.Vex Fuzz Factory is notable for establishing internal feedback loops that are inadvertently tied to the logic of circuit bending. This means that the pedal self-oscillates, producing an absurd yet controllable noise, akin to an air-raid siren.

Guitar effects and the boxes that generate them have married theory and practice, history and material, content and form. Such strange logics, inherent to all of these simple devices, radiate sincerity in their transgressive sounds. Or put differently, those “unmistakable sounds,” which can enchant an entire generation, are not entirely intentional, but are born from the accidental collisions between transistors, tubes, wiring, and luck.

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