Various experiments at electrically amplifying the vibrations of a string instrument date back to the early part of the twentieth century. Patents from the 1910s show telephone transmitters adapted and placed inside violins and banjos to amplify the sound. Hobbyists in the 1920s used carbon button microphones attached to the bridge, however these detected vibration from the bridge on top of the instrument, resulting in a weak signal. With numerous people experimenting with electrical instruments in the 1920s and early 1930s, there are many claimants to have been the first to invent an electric guitar.
Electric guitars were originally designed by luthiers, guitar makers, electronics enthusiasts, and instrument manufacturers. Guitar innovator Les Paul experimented with microphones attached to guitars. Some of the earliest electric guitars adapted hollow bodied acoustic instruments and used tungsten pickups. An electrically amplified guitar was developed by George Beauchamp in 1931. Commercial production began in late summer of 1932 by Electro-Patent-Instrument Company Los Angeles, a partnership of Adolph Rickenbacker, Paul Barth and George Beauchamp, the inventor. The wooden body of the prototype was built by Harry Watson, a craftsman who had worked for the National Resophonic Guitar Company (where the men met). By 1934 the company was renamed Rickenbacker Electro Stringed Instrument Company.
The need for the amplified guitar became apparent during the big band era as orchestras increased in size, particularly when guitars had to compete with large brass sections. The first electric guitars used in jazz were hollow archtop acoustic guitar bodies with electromagnetic transducers. By 1932 an electrically amplified guitar was commercially available. Early electric guitar manufacturers include: Rickenbacker (first called Ro-Pat-In) in 1932, Dobro in 1933, National, AudioVox and Volu-tone in 1934,Vega, Epiphone (Electrophone and Electar), and Gibson in 1935 and many others by 1936.
The solid body electric guitar is made of solid wood, without functionally resonating air spaces. Rickenbacher, later spelled Rickenbacker, offered a cast aluminum electric steel guitar, nicknamed "The Frying Pan" or "The Pancake Guitar", developed in 1931 with production beginning in the summer of 1932. This guitar sounds quite modern and aggressive as tested by vintage guitar researcher John Teagle. The company Audiovox built and may have offered an electric solid-body as early as the mid-1930s.
The first solid body "Spanish" standard guitar was offered by Vivi-Tone no later than 1934. An example of this model, featuring a guitar-shaped body of a single sheet of plywood affixed to a wood frame, can be seen in the Experience Music Project. Another early, substantially solid Spanish electric guitar, called Electro Spanish, was marketed by the "Rickenbacker" guitar company in 1935 and made of Bakelite. By 1936, the Slingerland company introduced a wooden solidbody electric model.
The earliest documented performance with an electrically amplified guitar was in 1932, by Gage Brewer. The Wichita, Kansas-based musician had an Electric Hawaiian A-25 (frypan, lap-steel) and a standard Electric Spanish from George Beauchamp of Los Angeles, California. Brewer publicized his new instruments in an article in the Wichita Beacon of October 2, 1932 and through performances that month. Brewer's original 1932 Ro-Pat-In Electro Spanish guitar can currently be viewed at the Wichita-Sedgwick County Historical Museum.
The first recordings using the electric guitar were by Hawaiian style players, including Andy Iona in 1933. Bob Dunn of Milton Brown's Musical Brownies introduced the electric Hawaiian guitar to Western Swing with his January 1935 Decca recordings, departing almost entirely from Hawaiian musical influence and heading towards Jazz and Blues. Alvino Rey was an artist who took this instrument to a wide audience in a large orchestral setting and later developed the pedal steel guitar for Gibson. An early proponent of the electric Spanish guitar was jazz guitarist George Barnes who used the instrument in two songs recorded in Chicago on March 1, 1938, "Sweetheart Land" and "It's a Low-Down Dirty Shame". Some incorrectly attribute the first recording to Eddie Durham, but his recording with the Kansas City Five was 15 days later. Durham introduced the instrument to a young Charlie Christian, who made the instrument famous in his brief life and would be a major influence on jazz guitarists for decades thereafter.
Gibson's first production electric guitar, marketed in 1936, was the ES-150 model ("ES" for "Electric Spanish"; and "150" reflecting the $150 price of the instrument, along with a matching amplifier). The ES-150 guitar featured a single-coil, hexagonally shaped "bar" pickup, which was designed by Walt Fuller. It became known as the "Charlie Christian" pickup (named for the great jazz guitarist who was among the first to perform with the ES-150 guitar). An early commercially successful solid-body electric guitar was the Fender Esquire in 1950.
Early proponents of the electric guitar on record include: Jack Miller (Orville Knapp Orchestra), Alvino Rey (Phil Spitalney Orchestra), Les Paul (Fred Waring Orchestra), Danny Stewart (Andy Iona Orchestra), George Barnes (under many aliases), Floyd Smith, Big Bill Broonzy, T-Bone Walker, George Van Eps, Charlie Christian (Benny Goodman Orchestra) Tampa Red, Memphis Minnie, and Arthur Crudup.
A functionally solid body electric guitar was designed and built by Les Paul from an Epiphone acoustic archtop. His "log guitar" (so called because it consisted of a simple 4x4 wood post with a neck attached to it and homemade pickups and hardware, with two detachable Swedish hollow body halves attached to the sides for appearance only) shares nothing in design or hardware with the solid body "Les Paul" model sold by Gibson. However, the feedback problem associated with hollow-bodied electric guitars was understood long before Paul's "log" was created in 1940; Gage Brewer's Ro-Pat-In of 1932 had a top so heavily reinforced that it essentially functioned as a solid-body instrument.
In 1945, Richard D. Bourgerie made an electric guitar pickup and amplifier for professional guitar player George Barnes. Bourgerie worked through World War II at Howard Radio Company making electronic equipment for the American military. Barnes showed the result to Les Paul, who then arranged for Bourgerie to have one made for him.
While guitar construction has many variations, in terms of the materials used for the body, the shape of the body, and the configuration of the neck, bridge, and pickups, there are features which are found in almost every guitar. The photo below shows the different parts of an electric guitar. The headstock (1) contains the metal machine heads, which are used for tuning; the nut (1.4), a thin fret-like strip of metal, plastic, graphite or bone which the strings pass over as they first go onto the fingerboard; the machine heads (1.1), which are worm gears which the player turns to change the string tension and thus adjust the tuning; the frets (2.3), which are thin metal strips which stop the string at the correct pitch when a string is pressed down against the fingerboard; the truss rod (1.2), a metal cylinder used for adjusting the tension on the neck (not found on all instruments); decorative inlay (2.2), a feature not found on lower-cost instruments.
The neck and the fretboard (2.1) extend from the body; at the neck joint (2.4), the neck is either glued or bolted to the body; the body (3) of this instrument is made of wood which is painted and lacquered, but some guitar bodies are also made of polycarbonate or other materials; pickups (3.1, 3.2), which are usually magnetic pickups, but which may also be piezoelectric transducer pickups; the control knobs (3.8) for the volume and tone potentiometers; a fixed bridge (3.4) -on some guitars, a spring-loaded hinged bridge called a "tremolo system" is used instead, which allows players to "bend" notes or chords down in pitch or perform a vibrato embellishment; and a plastic pickguard, a feature not found on all guitars, which is used to protect the body from scratches or cover the control cavity which holds most of the electric guitar's wiring.
The wood that the body (3) is made of is a very disputed subject considered by some to largely determine the sonic qualities of the guitar, while others believe that the sonic difference in a solid body guitar is very subtle between woods. In acoustic and archtop guitars there is a more pronounced sonic definition caused by the type of wood used. Typical woods include alder (brighter, but well rounded), swamp ash (similar to alder, but with more pronounced highs and lows), mahogany (dark, bassy, warm), poplar (similar to alder) and basswood (very neutral). Maple, a very bright tonewood, is also a popular body wood, but is very heavy. For this reason it is often placed as a 'cap' on a guitar made of primarily of another wood. Cheaper guitars are often made of cheaper woods, such as plywood, pine or agathis, not true hardwoods, which can affect the durability and tone of the guitar.Although most guitars are made from wood, any material may be used in the construction of a guitar. Materials such as plastic or cardboard are examples of unusual but possible materials that affect the overall sound of the guitar.
Compared to an acoustic guitar, which has a hollow body, electric guitars make comparatively little audible sound simply by having their strings plucked, and so electric guitars are normally plugged into a guitar amplifier, which makes the sound louder. When an electric guitar is strummed, the movement of the strings generates (i.e., "induces") a very small electric current in the magnetic pickups, which are magnets wrapped with coils of very fine wire. That current is then sent through a cable to a guitar amplifier. The current induced is proportional to such factors as the density of the string or the amount of movement over these pickups. That vibration is, in turn, affected by several factors, such as the composition and shape of the body.
Some "hybrid" electric-acoustic guitars are equipped with additional microphones or piezoelectric pickups (transducers) that sense mechanical vibration from the body. Because in some cases it is desirable to isolate the pickups from the vibrations of the strings, a guitar's magnetic pickups will sometimes be embedded or "potted" in epoxy or wax to prevent the pickup from having a microphonic effect.
Because of their natural inductive qualities, all magnetic pickups tend to pick up ambient and usually unwanted electromagnetic noises. The resulting noise, the so-called "hum", is particularly strong with single-coil pickups, and aggravated by the fact that very few guitars are correctly shielded against electromagnetic interference. The most frequent cause is the strong 50 or 60 Hz component that is inherent in the generation of electricity in the local power transmission system. As nearly all amplifiers and audio equipment associated with electrical guitars rely on this power, there is in theory little chance of completely eliminating the introduction of unwanted hum.
Double-coil or "humbucker" pickups were invented as a way to reduce or counter the unwanted ambient hum sounds (known as 60 cycle hum). Humbuckers have two coils of opposite magnetic and electric polarity. This means that electromagnetic noise hitting both coils should cancel itself out. The two coils are wired in phase, so the signal picked up by each coil is added together. This high combined inductance of the two coils leads to the richer, "fatter" tone associated with humbucking pickups. Optical pickups are a type of pickup which sense string and body vibrations using infrared LED light.