Electric Guitars

Electric guitar

 

An electric guitar is a guitar that uses the principle of direct electromagnetic induction to convert vibrations of its metal strings into electric audio signals. The signal generated by an electric guitar is too weak to drive a loudspeaker, so it is amplified before sending it to a loudspeaker. Since the output of an electric guitar is an electric signal, the signal may easily be altered using electronic circuits to add "color" to the sound. Often the signal is modified using effects such as reverb and distortion.

Invented in 1931, the electric guitar became a necessity as jazz musicians sought to amplify their sound. Since then, the electric guitar has become the most important instrument in popular music. It has evolved into a stringed musical instrument that is capable of a multitude of sounds and styles. It served as a major component in the development of rock and roll and countless other genres of music.

History

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 guitar makers 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. The first electrically amplified guitar was designed in 1931 by George Beauchamp, General Manager at National Guitar Corporation with Paul Barth who was Vice President.The maple body prototype for the one piece cast aluminum "Frying Pan" was built by Harry Watson, factory superintendent of National Guitar Corporation. Commercial production began in late summer of 1932 by the Ro-Pat-In Corporation (Electro-Patent-Instrument Company Los Angeles), a partnership of Beauchamp, Adolph Rickenbacker, and Paul Barth. 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 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.

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. 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 solid body 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.

The first recordings using the electric guitar were by Hawaiian style players, 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). The ES-150 achieved some popularity, but was suffered from unequal loudness across the six strings.

At an Engineering Fair in 1940, first prize went to NC State University physics professor Sidney Wilson for his invention of a solid body guitar, claimed by NC State University to be the first of its kind. They also maintain that the pickup on this guitar was the first to have individual polepieces for each string, which addressed the unequal loudness problem of the ES-150's single blade. However, a Gibson experimental bar pickup with polepieces has been documented by Duchossoir as early as 1939, and Gibson had introduced a metal covered pickup with individual poles by 1940 on the ES-100 and 150 models. Professor Wilson also disposed of the acoustical body, reasoning that it was not necessary for a fully electric instrument. He developed the guitar shown here and entered it in the annual engineering fair. Patents from academia were quite unusual in the 1940s, so Professor Wilson did not patent his invention.

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), Lonnie Johnson, 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 Epiphone 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.

Construction

 

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 most guitars. The photo below shows the different parts of an electric guitar. The headstock 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 used to keep place of where the notes of the guitar are.

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 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 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 a solid body electric guitar, the tone is only affected by the type of wood used in construction, when playing the guitar without an amplifier. This is why a hollow aluminum body Fender Stratocaster's tone is identical to that of a swamp ash body Fender Stratocaster, equipped with the same electronics components, strings and pickups.

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.

The guitar output jack is typically designed for monaural function. On many guitars with active electronics a stereo jack may be installed but is wired for mono sound. The extra "ring" lug on the jack is then used to break the ground connection to the on-board battery thus preserving battery life when the guitar is unplugged. These guitars require use of a mono plug to close the internal switch and connect the battery to ground. Standard guitar cables are outfitted with a high impedance 1/4 inch (6.35 mm) mono plug. These utilize a tip and sleeve configuration referred to as a TS connector.

A few guitars are actually set up for stereo, for example Rickenbacker guitars equipped with Rick-O-Sound. There are a variety of ways the "stereo" effect may be implemented. Commonly, but not exclusively, stereo guitars route the neck and bridge pickups to separate output buses on the guitar. A stereo cable can then route each pickup to its own signal chain or amplifier. For these applications, the most popular connector is a high impedance 1/4 inch plug with a tip, ring and sleeve configuration also known as a TRS connector. Some studio instruments, notably certain models of Gibson Les Paul, incorporate a low impedance 3-pin XLR connector for balanced audio. Many exotic arrangements and connectors are employed to support features such as midi and hexaphonic pickups.

Bridge and tailpiece systems

The bridge and tailpiece, while serving separate purposes, work closely together as design elements to affect the playing style of the guitarist and the sound of the instrument. There are four basic types of bridge/tailpiece systems found on electric guitars. Within these four types there are many variants.

Hard-tail

A hard-tail guitar bridge incorporates hardware that anchors the strings at or directly behind the bridge and is fastened securely to the top of the instrument. These may be found on carved top guitars such as the Gibson Les Paul, Paul Reed Smith models as well as on slab body guitars like the Music Man Albert Lee, and Fender guitars that are not vibrato arm equipped.

Floating tailpiece

A floating tailpiece (similar to a violin's) is sometimes called a trapeze tailpiece and is fastened to the body at the base of the guitar. These are often seen on Rickenbackers, Gretschs, Epiphones, a wide variety of archtop guitars, particularly jazz-boxes and the 1952 Gibson Les Paul.

Vibrato arms

Pictured is a tremolo arm or vibrato tailpiece style bridge/tailpiece system often called a whammy bar or trem. It uses a lever ("vibrato arm") attached to the bridge which can slacken or tighten the strings temporarily, changing the pitch, thereby creating a vibrato or a portamento effect. Early vibrato systems tended to be unreliable and cause the guitar to go out of tune quite easily. They also had a limited range. Later Fender designs were better, but Fender held the patent on these, so other companies used older designs for many years.

 

Detail of a Squier-made Fender Stratocaster. Note the vibrato arm, the 3 single-coil pickups, the volume and tone knobs.

With the expiration of the Fender patent on the Stratocaster-style vibrato, various improvements on this type of internal, multi-spring vibrato system are now available. Floyd Rose introduced one of the first improvements on the vibrato system in many years when in the late 1970s he began to experiment with "locking" nuts and bridges which work to prevent the guitar from losing tuning even under the most heavy whammy bar acrobatics.

String-through body

 

Tune-o-matic with "strings through the body" construction (without stopbar)

The fourth type of system employs string-through body anchoring. The strings pass over the bridge saddles and then through holes drilled through the top of the guitar body to the back. The strings are typically anchored in place at the back of the guitar by metal ferrules. It is widely believed that this design improves a guitar's sustain and timbre. Examples of string-through bodies on guitars include the Fender Telecaster Thinline, Telecaster Deluxe, B.C.Rich IT Warlock and Mockingbird.

Pickups

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.

 

A close-up of the pickups on a Fender Squier "Fat Strat" guitar; on the left is a "humbucker" pickup and on the right are two single-coil pickups.

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. Piezoelectric pickups use a "sandwich" of quartz crystal or other piezoelectric material placed in the body of the guitar, usually under the bridge, that reacts to the changes in pressure caused by string and body vibration; these pickups are generally not sensitive to EMI.

Guitar necks

Electric guitar necks can vary according to composition as well as shape. The primary metric used to describe a guitar neck is the scale length, which is the overall length of the strings from the nut to the bridge. A typical Fender guitar uses a 25.5 inch scale length, while Gibson uses a 24.75 inch scale length in their Les Paul. While the scale length of the Les Paul has often claimed to be 24.75 inches, it has varied through the years by as much as a half inch. The frets are placed proportionally according to the scale length; thus, the shorter the scale length, the closer the spacing of the frets. Opinions vary regarding the effect of scale length on tone and feel. Generally, it is felt that longer scale length contributes to greater amplitude. Reports of playing feel are greatly complicated by the many factors involved in this perception. String gauge and design, neck construction and relief, guitar setup, playing style and other factors contribute to the subjective impression of playability or feel.

Necks are described as bolt-on, set-in, or neck-through depending on how they are attached to the body. Set-in necks are glued to the body in the factory, and are said to have a warmer tone and greater sustain; this is the most traditional type of joint. Bolt-on necks were pioneered by Leo Fender to facilitate easy adjustment and replacement of the guitar neck. Neck-through instruments extend the neck itself to form the center of the guitar body, and are known for long sustain and for being particularly sturdy. While a set neck can be carefully unglued by a skilled luthier, and a bolt-on neck can simply be unscrewed, a neck-through design is difficult or even impossible to repair, depending on the damage. Historically, the bolt-on style has been more popular for ease of installation and adjustment; since bolt-on necks can be easily removed, there is an after-market in replacement bolt-on necks from companies such as Warmoth and Mighty Mite. Some instruments, notably most Gibson models, have continued to use set/glued necks. Neck-through bodies are somewhat more common in bass guitars.

The materials used in the manufacture of the neck, selected for dimensional stability and rigidity, are alleged to influence the tone of the instrument. Hardwoods are very much preferred, with maple, mahogany, and ash topping the list. The neck and fingerboard can be made from different materials, such as a maple neck with a rosewood fingerboard. In the 1970s, exotic man-made materials such as aircraft grade aluminum, carbon fiber, and ebonol began to be used by designers John Veleno, Travis Bean, Geoff Gould, and Alembic. Along with the engineering advantages, some have felt that in relation to the rising cost of rare 'tonewoods' man-made materials may be economically viable. However, artificial materials have not replaced the popularity of wood in production instruments, although they are sometimes used in conjunction with traditional materials. Vigier guitars are one example. Vigier uses a wooden neck and reinforces it by embedding a light, carbon fiber rod to replace the heavier steel bar or adjustable steel truss rod typically employed. After-market necks made entirely from carbon fiber can be retrofitted to existing bolt-on instruments. Few, if any, extensive formal investigations have been widely published to confirm or refute claims over the effects of different woods or materials on an electric guitar's sound.

There are several different neck shapes used on guitars, including shapes known as C necks, U necks, and V necks. These refer to the cross-sectional shape of the neck (especially near the nut). There are also several sizes of fret wire available, with traditional players often preferring thin frets, and metal shredders liking thick frets. Thin frets are considered better for playing chords, while thick frets allow lead guitarists to bend notes with less effort. An electric guitar with a neck which folds back called the "Foldaxe" was designed and built for Chet Atkins by Roger C. Field. Steinberger guitars developed a line of exotic, carbon fiber instruments without headstocks, with tuning done on the bridge instead.

Just as neck shapes vary so do fingerboards. Fingerboards are the surface of the neck into which frets are set. This surface has a radius in cross section optimized to accommodate finger movement for different playing techniques. They typically range from nearly flat, a very large radius, to radically arched, a small radius. An example of a small radius, the vintage Fender Telecaster typically has approximately a 7 inch radius fingerboard. Some manufacturers have experimented with fret design, fret layout, number of frets, and modification of the fingerboard surface for a variety of reasons. Some innovations were intended to improve playability by ergonomic means such as Warmoth Guitars compound radius fingerboard. Scalloped fingerboards added enhanced microtonality during fast legato runs. Fanned frets permit each string to have an optimal playing tension and enhanced musicality. Some guitars have no frets whatsoever and others, like the Gittler guitar, have no neck in the traditional sense.

Sound and effects

While an acoustic guitar's sound is largely dependent on the vibration of the guitar's body and the air within it, the sound of an electric guitar is largely dependent on a magnetically induced electrical signal, generated by the vibration of metal strings near sensitive pickups. The signal is then "shaped" on its path to the amplifier by using a range of effect devices or circuits that modify the tone and characteristics of the signal. The amplifiers and speakers used also add (intentional) coloration to the final sound.

Built-in sound shaping

Electric guitars usually have up to three magnetic pickups. Identical pickups will have different tones depending on how near they are to the neck or bridge, with bridge pickups having a bright or trebly timbre, and neck pickups being more warm or bassy. The type of pickup also affects tone, with dual-coil pickups sounding warmer, thicker, perhaps even muddy, and single coil pickups sounding clear, bright, perhaps even biting. Guitars do not have to be fitted with a uniform type of pickup: a common mixture is the "fat strat" arrangement of one dual-coil at the bridge position, with single coils in the middle and neck positions.

Where there is more than one pickup, selector switching is fitted. These often allow the outputs of two or more pickups to be combined, so that two-pickup guitars have three-way switches, and three-pickup guitars have five-way switches. Further circuitry is sometimes provided to combine the pickups in different ways. For instance, phase switching places one pickup out of phase with the other(s), leading to a "honky", "nasal", or "funky" sound. Individual pickups can also have their timbre altered by switches, typically coil tap switch, which effectively short-circuits some of a dual-coil pickup's windings, giving a tone like a single coil pickup.

The final stages of on-board sound-shaping circuitry are the volume control (potentiometer) and tone control (which "rolls off" the treble frequencies). Where there are individual volume controls for different pickups, and where pickup signals can be combined, they would affect the timbre of the final sound by adjusting the balance between pickups from a straight 50:50.

The strings fitted to the guitar also have an influence on tone. Rock musicians often prefer the lightest gauge of roundwound string, which are easier to bend, while jazz musicians go for heavier, flatwound strings with a rich, dark sound.

Recent guitar designs may incorporate much more complex circuitry than described above: see Digital and synthesizer guitars, below.

Classic amplifier sounds

In the 1960s, some guitarists began exploring a wider range of tonal effects by distorting the sound of the instrument. To do this, they used overdrive — increasing the gain, of the preamplifier beyond the level at which the signal could be faithfully reproduced, resulting in a "fuzzy" sound. This effect is called "clipping" by sound engineers, because when viewed with an oscilloscope, the wave forms of a distorted signal appear to have had their peaks "clipped off", approximating a square wave. This was not actually a new development in the instrument, but rather a shift of aesthetics, the sound having not been recognized as desirable previously.

Distortion achieved by overdrive necessarily involves high volumes and is therefore often combined with audio feedback.

After distortion became popular, amplifier manufacturers included various provisions for it, making amps easier to overdrive, and providing separate "dirty" and "clean" channels so that distortion could easily be switched in and out. The distortion characteristics of vacuum tube amplifiers are particularly sought-after, and various attempts have been made to emulate them without the disadvantages (fragility, low power, expense) of actual tubes.

Guitar amplifiers have long included at least a few effects, often tone controls and a spring reverb unit. The use of offboard effects is assisted by the provision of effect loops, an arrangement that allows effects to be taken out of circuit when not required.

Effects units

 

A Boss distortion pedal in use.

In the 1960s, the tonal palette of the electric guitar was further modified by introducing an Effects unit in its signal path. modifiers, wave-shaping circuits, voltage-controlled oscillators, or digital delays. Effects units come in several formats, the most common of which are the stomp-box and the rack-mount unit. A "stomp box" (or "pedal") is a small metal or plastic box containing the circuitry which is placed on the floor in front of the musician and connected in line with the patch cord connected to the instrument. The box is typically controlled by one or more foot-pedal on-off switches and it typically contains only one or two effects. "Guitar pedalboards" are used by musicians who use multiple stomp-boxes; these may be a DIY project made with plywood or a commercial pedalboard.

A rack-mount effects unit may contain the identical electronic circuit, but is mounted in a standard 19" equipment rack. Usually, however, rack-mount effects units contain several different types of effects. They are typically controlled by knobs or switches on the front panel, and often by a MIDI digital control interface.

Typical effects include:-

• Effects such as stereo chorus, phasers and flangers which shift the pitch of the signal by a small and varying amount, creating swirling, shimmering and whooshing noises.
• Effects such as octavers, which displace pitch by an exact musical interval.
• Distortion, such as transistor-style fuzz, or effects incorporating or emulating vacuum tube distortion.
• Filters such as wah-wah
• Envelope shapers, such as compression/sustain or volume/swell.
• Time-shift effects such as delay and reverb.

Modern amplifier techniques

In the 1970s, as effects pedals proliferated, their sounds were combined with tube amp distortion at lower, more controlled volumes by using power attenuators such as Tom Scholz' Power Soak as well as re-amplified dummy loads such as Eddie Van Halen's use of a variac, power resistor, post-power-tube effects, and a final solid-state amp driving the guitar speakers. A variac is one approach to power-supply based power attenuation, to make the sound of power-tube distortion more practically available.

Recent amplifiers may include digital technology similar to modern effects pedals, including the ability to model or emulate a variety of classic amps.

Digital and software-based effects

 

The Zoom 505 multi-effect pedal.

A multi-effects device (also called a "multi-FX" device) is a single electronics effects pedal or rackmount device that contains many different electronic effects. In the late 1990s and throughout the 2000s, multi-FX manufacturers such as Zoom and Korg produced devices that were increasingly feature-laden. Multi-FX devices allow several of the effects to be used together, and most devices allow users to set "preset" combinations of different effects including distortion, chorus, reverb, compression, and so on. This allows musicians to have quick on-stage access to different effects combinations. Some multi-FX pedals contain modelled versions of well-known effects pedals or amplifiers.

 

The Boss GT-8 is a higher-end multi-effect processing pedal; note the preset switches and patch bank footswitches and built-in expression pedal.

Multi-effects devices have garnered a large share of the effects device market because they offer the user such a large variety of effects in a single package. A low-priced multi-effects pedal may provide 20 or more effects for the price of a regular single-effect pedal. More expensive multi-effect pedals may include 40 or more effects, amplifier modelling, and the ability to combine effects and/or modelled amp sounds in different combinations, as if the user was using multiple guitar amps. More expensive multi-effects pedals may also include more input and output jacks (e.g., an auxiliary input or a "dry" output), MIDI inputs and outputs, and an expression pedal, which can control volume or modify effect parameters (e.g., the rate of the simulated rotary speaker effect).

By the 1980s and 1990s, software effects became capable of replicating the analog effects used in the past. These new digital effects attempted to model the sound produced by analog effects and tube amps, to varying degrees of quality. There are many free guitar effects computer programs for computers that can be downloaded via the Internet. Now, computers with sound cards can be used as digital guitar effects processors. Although digital and software effects offer many advantages, many guitarists still use analog effects.

Synthesizer and digital guitars

In 2002, Gibson announced the first digital guitar, which performs analog-to-digital conversion internally. The resulting digital signal is delivered over a standard Ethernet cable, eliminating cable-induced line noise. The guitar also provides independent signal processing for each individual string. Also, in 2003 amp maker Line 6 released the Variax guitar. It differs in some fundamental ways from conventional solid-body electrics. For example it uses piezoelectric pickups instead of the conventional electromagnetic ones, and has an on-board computer capable of modifying the sound of the guitar to model the sound of many instruments.

Playing techniques

 

A prepared guitar

The sound of a guitar is not only adapted by electronic sound effects, but also heavily by all kinds of new techniques developed or becoming possible in combination with the electric amplification. This is called extended technique.

Extended techniques include:-

• String bending (or radial finger vibrato.). This is not quite unique to the electric instrument, but is greatly facilitated by the light strings typically used on solid body guitars.
• Neck bending, by holding the upper arm on the guitar body and bending the neck either to the front or pulling it back. This is used as a substitute for a tremolo bar, although not as effective and too powerful of force use could snap the guitar neck.
• The use of the whammy bar or "tremolo" arm, including the extreme technique of dive bombing.
• Tapping, in which both hands are applied to the fretboard.
• Pinch harmonics, sometimes called "squealies". This technique involves adding the edge of the thumb or the tip of the index finger on the picking hand to the regular picking action, resulting in a high pitched sound.
• Volume swells, in which the volume knob is repeatedly rolled to create a violin-like sound. Note that the same result can also be accomplished through the use of an external swell pedal, although the knob technique can enhance showmanship and conveniently eliminate the need for another pedal.
• Use of audio feedback to enhance sustain and change timbre.
• Substitution of another device for the plectrum, for instance the cello bow (as famously used by Jimmy Page) and the e-bow, (a device using electromagnetic feedback to vibrate strings without direct contact). Like feedback, these techniques increase sustain, bring out harmonics and change the acoustic envelope.
• Sustainers built into the guitar itself.
• Use of slide or bottlenecks.
• Sometimes guitars are even adapted with extra modifications to alter the sound, such as Prepared guitar and 3rd bridge.

Other techniques such as axial finger vibrato, pull-offs, hammer-ons, palm muting, harmonics and altered tunings are also used on the classical and acoustic guitar. Shred guitar is a genre involving a number of extended techniques.

Types

 

solid body

Solid body electric guitars have no vibrating soundboard to amplify string vibration as is the case with acoustic guitars. Solid body instruments depend on electric pickups and an amplifier (or amp) and speaker. The solid body ensures that the amplified sound will reproduce the string vibration alone, thus avoiding the "wolf tones" and unwanted feedback associated with amplified acoustic guitars prior to the introduction of the piezoelectric sensor pickup. These guitars are generally made up of hardwood with a polyester or lacquer finish. In large production facilities, the wood is stored for 3 to 6 months in a wood-drying kiln before being cut to shape. Premium custom built guitars are frequently made with much older, hand selected wood.

One of the first solid body guitars was invented by Les Paul. Gibson did not present their 'Les Paul' guitar prototypes to the public, as they did not believe it would catch on. The first mass-produced solid-body guitar was Fender's Broadcaster (later to become the 'Telecaster') first made in 1948, five years after Les Paul made his prototype. The Gibson Les Paul appeared soon after to compete with the Broadcaster. Another notable solid-body design is the Fender Stratocaster, which was introduced in 1954 and became extremely popular among musicians in the 1960s and 1970s for its wide tonal capabilities and more comfortable ergonomics than other models.

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