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A guitar is a stringed musical instrument. It is often played with the fingers of the left hand[1]. The right hand plucks the strings with either the fingers or a plectrum (guitar pick). The sound is produced by vibrating strings, which in turn resonate the body and neck.
Guitars may be acoustic, electric (i.e. with electrical amplification) or both. Classical guitars are also present in the guitar family, although they are not as popular as the prior two. Guitars have a body acting mostly as a resonator, which can be hollow in acoustic guitars or solid in most electric guitars, and a neck. Typically, a headstock extends from the neck for tuning. Guitars are made and repaired by luthiers.
Guitars are used in a variety of musical styles. Guitars are widely known as a solo classical instrument, and the primary instrument in blues and rock music.
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Instruments similar to what we know as the guitar have been popular for at least 5,000 years. The guitar appears to be derived from earlier instruments known in ancient central Asia. Instruments very similar to the guitar appear in ancient carvings and statues recovered from the old Iranian capitol of Susa. The modern word, guitar, was adopted into English from Spanish, possibly from earlier Greek word kithara. Prospective sources for various names of musical instruments that guitar could be derived from all appear to be a combination of two Indo-European roots: guit-, similar to Sanskrit sangeet meaning "music", and -tar a widely attested root meaning "chord" or "string".
The word guitar may also be a Persian loanword to Iberian Arabic. The word qitara is an Arabic name for various members of the lute family that preceded the Western guitar. The name guitar was introduced into Spanish when guitars were brought into Iberia by the Moors after the 10th century. (See related article).
The Spanish vihuela appears to be an intermediate form between the ancestral guitar and the modern guitar, with lute-style tuning and a small, but guitar-like body. It is not clear whether this represents a transitional form or simply a design that combined features from the two families of instruments. (See the article on the lute for further history.)
The electric guitar was invented by Adolf Rickenbacher, with the help of George Beauchamp and Paul Berth, in 1931. Rickenbacher was the inventor of the horseshoe-magnet pickup. However, it was Danelectro that first produced electric guitars for the wider public. Danelectro also pioneered tube amp technology.
Guitar consists of several parts. Refer to appropriate article for description of a part:
The headstock is located at the end of the guitar neck. It is fitted with the tuning machines for pitch adjusting. Traditional layout of tuners is "3+3" which means 3 top tuners and 3 bottom ones. Some electric guitars feature 6 in-line tuners or even 4+2.
The nut is a small strip of ivory, bone, plastic, brass, graphite, or other medium-hard material that braces the strings at the joint where the headstock meets the fretboard. It is grooved to hold the strings in place, and it is one of the endpoints of the strings' tension. The material used also affects the sound of the guitar.
Also called the fingerboard, the fretboard is a long plank of wood embedded with metal frets that comprises the top of the neck. It is flat on classical guitars and slightly curved crosswise on acoustic and electric guitars. The curvature of the fretboard is measured by the fretboard radius, which is the radius of a hypothetical circle of which the fretboard's surface constitutes a segment. The smaller the fretboard radius, the more noticably curved the fretboard is. Pinching a string against the fretboard effectively shortens the vibrating length of the string, producing a higher tone (a string, unfingered, will vibrate from the saddle to the nut; once fingered, it will vibrate only along the distance between the saddle and the fret directly before the finger). Fretboards are most commonly made of rosewood, ebony, and maple.
Frets are metal strips (usually nickel alloy) embedded along the fretboard which are placed in points along the length of string that divide it mathematically. When strings are pressed down behind them, frets shorten the strings' vibrating lengths to produce different pitches- each one spaced a half-step apart on the 12 tone scale. For more on fret spacing, see the Strings and Tuning section below. Frets are usually the first permanent part to wear out on a heavily played electric guitar. They can be re-shaped to a certain extent and can be replaced as needed. Frets also indicate fractions of the length of a string (the string midpoint is at the 12th fret; one-third the length of the string reaches from the nut to the 7th fret, the 7th fret to the 19th, and the 19th to the saddle; one-quarter reaches from nut to fifth to twelfth to twenty-fourth to saddle). This feature is important in playing harmonics. Frets are available in several different gauges, depending on the type of guitar and the player's style.
The truss rod is an adjustable metal rod that runs along the inside of the neck, adjusted by a hex nut or an allen-key bolt usually located either at the headstock (under a cover) or just inside the body of the guitar, underneath the fretboard (accessible through the sound hole). The truss rod counteracts the immense amount of tension the strings place on the neck, bringing the neck back to a straighter position. The truss rod can be adjusted to compensate for changes in the neck wood due to changes in humidity or to compensate for changes in the tension of strings. Tightening the rod will curve the neck back and loosening it will return it forward. Adjusting the truss rod affects the intonation of a guitar as well as affecting the action (the height of the strings from the fingerboard). Some truss rod systems, called "double action" truss systems, will tighten both ways, allowing the neck to be pushed both forward and backward (most truss rods can only be loosened so much, beyond which the bolt will just come loose and the neck will no longer be pulled backward). Classical guitars do not have truss rods, as the nylon strings do not put enough tension on the neck for one to be needed.
Inlays are visual elements set into the exterior wood on a guitar. The typical locations for inlay are on the fretboard, headstock, and around the soundhole (called a rosette on acoustic guitars). Inlays range from simple plastic dots on the fretboard to fantastic works of art covering the entire exterior surface of a guitar (front and back).
Fretboard inlays are most commonly shaped like dots, diamond shapes, parallelograms, or large blocks in between the frets. Dots are usually inlaid into the upper edge of the fretboard in the same positions, small enough to be visible only to the player. Some manufacturers go beyond these simple shapes and use more creative designs such as lightning bolts or letters and numbers. The simpler inlays are often done in plastic on guitars of recent vintage, but many older, and newer, high-end instruments have inlays made of mother of pearl, abalone, ivory, colored wood or any number of exotic materials. On some low-end guitars, they are just painted. Many classical guitars have no inlays at all; the player himself sometimes will make them with a marker pen or correction fluid.
The most popular fretboard inlay scheme involves single inlays on the 3rd, 5th, 7th, 9th, 15th, 17th, 19th, and 21st frets, and double inlays on the 12th, sometimes 7th, and (if present) 24th fret. Pros of such scheme include its symmetry about the 12th fret and symmetry of every half (0-12 and 12-24) about the 7th and 19th frets. However, playing these frets, for example, on E string would yield notes E, G, A, B, C# that barely make a complete musical mode by themselves.
A less popular fretboard inlay scheme involves inlays on 3rd, 5th, 7th, 10th, 12th, 15th, 17th, 19th, 22nd and 24th frets. Playing these frets, for example, on E string yields notes E, G, A, B, D that fit perfectly into E minor pentatonic. Such a scheme is very close to piano keys coloring (which involves black coloring for sharps that pentatonic consists of) and of some use on classic guitars.
Beyond the fretboard inlay, the headstock and soundhole are also commonly inlaid. The manufacturer's logo is commonly inlaid into the headstock. Sometimes a small design such as a bird or other character or an abstract shape also accompanies the logo. The soundhole designs found on acoustic guitars vary from simple concentric circles to delicate fretwork. Many high-end guitars have more elaborate decorative inlay schemes. Often the edges of the guitar around the neck and body and down the middle of the back are inlaid. The fretboard commonly has a large inlay running across several frets or the entire length of the fretboard, such as a long vine creeping across the fretboard. Most acoustic guitars have an inlay that borders the sides of the fretboard, and some electrics (namely Fender Stratocasters) have a black inlay running on the back of the neck, from about the body to the middle of the neck, commonly referred to as a skunk stripe.
Some very limited edition high-end or custom-made guitars have artistic inlay designs that span the entire front (or even the back) of the guitar. These designs use a variety of different materials and are created using techniques borrowed from furniture making. While these designs are often just very elaborate decorations, they are sometimes works of art that even depict a particular theme or a scene. Although these guitars are often constructed from the most exclusive materials, they are generally considered to be collector's items and not intended to be played. Large guitar manufacturers often issue these guitars to celebrate a significant historical milestone.
A guitar's frets, fretboard, tuners, headstock, and truss rod, all attached to a long wooden extension, collectively comprise its neck. The wood used to make the fretboard will usually differ from the wood in the rest of the neck. The bending stress on the neck is considerable, particularly when heavier gauge strings are used (see Strings and tuning), and the ability of the neck to resist bending (see Truss rod) is important to the guitar's ability to hold a constant pitch during tuning or when strings are fretted. The rigidity of the neck with respect to the body of the guitar is one determinant of a good instrument versus a poor one. Conversely, the ability to change the pitch of the note slightly by deliberately bending the neck forcibly with the fretting arm is a technique occasionally used, particularly in the blues genre and those derived from it, such as rock and roll. The shape of the neck can also vary, from a gentle "C" curve to a more pronounced "V" curve.
This is the point at which the neck is either bolted or glued to the body of the guitar. Almost all acoustic guitars, with the primary exception of Taylors, have glued (or set) necks, while electric guitars are constructed using both types. Set necks usually feature dovetail joints, which offer stability and sustain. Other commonly used neck joints include mortise-and-tenon joints (such as those used by CF Martin & Co. guitars), and Spanish Heel style neck joints (commonly found in classical guitars). Bolt-on necks, though they are historically associated with cheaper instruments, do offer greater flexibility in the guitar's set-up, and allow easier access for neck joint maintenance and repairs. Some very high-end instruments may not have a neck joint at all, having the neck and sides built as one piece and the body built around it.
The body of the instrument is a major determinant of the overall sound for acoustic guitars. The guitar top, or soundboard, is a finely crafted and engineered element often made of spruce, redcedar or mahogany. This thin (often 2 or 3 mm thick) piece of wood, strengthened by different types of internal bracing, is considered to be the most prominent factor in determining the sound quality of a guitar. The majority of the sound is caused by vibration of the guitar top as the energy of the vibrating strings is transferred to it. Different patterns of wood bracing have been used through the years by luthiers; to not only strengthen the top against collapsing under the tremendous stress exerted by the tensioned strings (Torres, Hauser, Ramirez, Fleta being among the most influential designers of their time), but also to affect the resonation of the top. The back and sides are made out of a variety of woods such as mahogany, Indian rosewood and highly regarded Brazilian rosewood (Dalbergia nigra). Each one is chosen for their aesthetic effect and structural strength, and can also play a significant role in determining the instrument's timbre. These are also strengthened with internal bracing, decorated with inlays and purfling, and subjected to a lot of abuse.
Most electric guitar bodies are made of wood. This wood is rarely one solid piece, as laminating hardwoods in the proper way can produce a body of exceptional strength and superior tone. The most common woods used for electric guitar body construction include maple, basswood, ash, poplar, alder, and mahogany. Many bodies will consist of good sounding but inexpensive woods, like ash, with a "top", or thin layer of another, more attractive wood (such as maple with a natural "flame" pattern) glued to the top of the basic wood. Guitars constructed like this are often called "flame tops". The body is usually carved or routed to accept the other elements, such as the bridge, pickup, neck, and other electronic components. Many higher-end electrics have a nitro-cellulose laquer finish on the top, which promotes resonance.
Usually on acoustic guitars, the resonating chamber or sound hole allows the acoustic guitar to be played without amplification. It is normally a round hole in the top of the guitar, though some may have different shapes or multiple holes. This allows the vibrations from the back and sides of the guitar to be pushed forward toward the listener.
The electric guitar is usually not very loud when played without an amplifier. Pickups are electronic devices attached to a guitar that detect (or "pick up") string vibrations and allow the sound of the string to be amplified. Pickups are usually placed right underneath the guitar strings. The most common type of pickups contain magnets that are tightly wrapped in copper wire. This allows the pickups to measure the movement of the steel guitar string within the magnetic field above the pickup. Some acoustic guitars also have microphones or pickups built into them for stage work. Pickups work on a similar principle to a generator in that the vibration of the strings causes a small current to be created in the coils surrounding the magnets. This signal is later amplified by an amplifier. However, a new type of pickup, called a Q-Tuner pickup, has been developed that measures the magnetic flux density of multiple magnets located in the pickup. These pickups produce a better tone and pick up harmonic frequencies better than standard pickups, but they cost more and are more difficult to wire.
Traditional electric pickups are either single-coil or double-coil. Double-coil pickups are also known as humbuckers for their noise-cancelling ability. The type and model of pickups used can have large effects on the tone of the guitar. Typically, humbuckers are used by guitarists seeking a heavier sound. Some guitars need a battery to power their pickups and/or pre-amp; these guitars are referred to as having "active electronics", as opposed to the typical "passive" circuits.
Guitar Synthesisers may have specialist 'cluster' pickups, effectively giving each string its own pickup.
On guitars that have them, these components and the wires that connect them allow the player to control some aspects of the sound like volume or tone. These at their simplest consist of passive components such as potentiometers and capacitors, but may also include specialized integrated circuits or other active components requiring batteries for power, for preamplification and signal processing, or even for assistance in tuning. In many cases the electronics have some sort of magnetic shielding to prevent pickup of external interference and noise.
This is the decorative edge found around the body of an acoustic guitar. Its purpose is not merely decorative, however. Because of the construction methods, the edges of the body are typically the weakest point of the acoustic guitar. There is not much wood there, as the sides have to be thin to allow for bending, and the top and back have to be thin to allow the string vibrations to resonate. Trying to connect two thin pieces of wood at a 90 degree angle is an engineering challenge. So to help, the purfling is used. The corners are overbuilt, using a triangular piece of scored wood (called a kerfed lining) on the interior of the instrument to allow it to follow the contours, and is glued in place. During final construction, a small section of the outside corners is carved or routed out and then filled in with the purfling or binding material.
In mass produced guitars, the binding or purfling is almost exclusively high quality plastic. Once the purfling is glued in place, it is an integral part of the guitar, and contributes greatly to the durability of the instrument, since plastic tends not to split as wood does upon impact.
The main purpose of the bridge on an acoustic guitar is to transfer the vibration from the strings to the soundboard, which vibrates the air inside of the guitar, thereby amplifying the sound produced by the strings.
On both electric and acoustic guitars, the bridge holds the strings in place. From there, the variations are astounding. There may be some mechanism for raising or lowering the bridge to adjust the distance between the strings and the fretboard (action), and/or fine-tuning the intonation of the instrument. Some are springloaded and feature a "whammy bar", a removable arm which allows the player to modulate the pitch moving the bridge up and down. The whammy bar is sometimes incorrectly referred to as a "tremolo bar"; unlike the change in pitch that the whammy bar produces, a tremolo is a quick oscillation of the volume. Some bridges allow for alternate tunings at the touch of a button.
Also known as a scratchplate. This is usually a piece of plastic or other laminated material that protects the finish of the top of the guitar. In some electric guitars, the pickups and most of the electronics are mounted on the pickguard. On acoustic guitars and many electric guitars, the pickguard is mounted directly to the guitar top, while on guitars with carved tops (e.g. the Gibson Les Paul), the pickguard is elevated. The Pickguard is more often than not used in styles such as flamenco, which tends to use the guitar as a percussion instrument at times, rather than for instance, a classical guitar.
Guitars have frets on the fingerboard to fix the positions of notes and scales, which gives them equal temperament. Consequently, the ratio of the widths of two consecutive frets is the twelfth root of two
, whose numeric value is about 1.059463. The twelfth fret divides the string in two exact halves and the 24th fret (if present) divides the string in half yet again. Every twelve frets represents one octave.
Guitars usually have six strings, although there are variations on this, the most common being a twelve-string guitar; the seven string guitar; the ukulele, which has four strings; and the bass guitar, which usually has four strings but also exists in five, six, eight, and twelve-string versions. There are also more exotic models involving multiple necks and pickups. The vihuela, a guitar variation which emerged in 16th century Spain, has six double strings made of gut.
The weight of a string is determined by its diameter and is normally measured in thousandths of an inch. The larger the diameter the heavier the string is (with thinner strings being lighter). Heavier strings require more tension for the same pitch and are consequently harder to hold on to the fretboard. Heavier strings will also produce a louder note and for this reason steel-strung acoustic guitars will normally be strung heavier than electric guitars. On electric guitars, heavier strings may also produce a thicker tone, leading to their use by rhythm guitarists in rock music.
A variety of different tunings are used. The most common by far, known as "standard tuning" (EADGBE), is as follows:
Standard tuning has evolved to provide a good compromise between simple fingering for many chords and the ability to play common scales with minimal left hand movement.
The separation of adjacent strings by a 5-semitone interval (a perfect fourth) allows the notes of the chromatic scale to be played with each of the four fingers of the left hand controlling one of the first four frets (index finger on fret 1, little finger on fret 4, etc.). It also yields a symmetry and intelligibility to fingering patterns.
The major third interval (two whole tones = four semitones = four frets) between the g and b' strings tunes the b' and e' strings a semitone flatter than if the pattern of perfect fourths were followed for all six strings. Though this breaks the fingering pattern of the chromatic scale (though only by making the little finger redundant on the g string) and thus the symmetry, it eases the playing of some often-used chords and scales and it provides more diversity in fingering possibilities. It also means that each open string is on a whole note, allowing it to be the root of a major scale, and that when the guitar is strummed with all strings open (as sometimes happens momentarily during difficult chord changes in frenetic passages of modern songs) it plays a tolerable chord (Em7#9sus4).
Some common alternate tunings:
Each of the six strings can be alternately tuned as low as a whole step lower and as much as a whole step higher without stressing the neck or the strings. With five possible tunings for each string (+2, +1, 0, -1, and -2), there can be as many as 15,625 possible tunings for a six-string guitar.
Note that a standard guitar sounds one octave below pitch as written in standard notation. That is, the first string in standard tuning plays the E note that is a major third above middle C, and is written on the staff as a major tenth above middle C.
There are also tenor guitars, baritone guitars tuned ADGCEA (or GDGCDG, GDGCEA, GCGCEG, etc.) a fifth lower than a standard (prime) guitar, treble guitars tuned a fourth higher than a prime guitar, and contrabass guitars, which are tuned one octave lower than prime guitars.
Broadly speaking, guitars can be divided into 2 categories:
The electric bass is similar in tuning to the traditional double bass viol. Hybrids of acoustic and electric guitars are also common. There are also more exotic varieties, such as double-necked guitars, all manner of alternate string arrangements, fretless fingerboards (used almost exclusively on bass guitars, meant to emulate the sound of a stand-up bass), and such.
The guitar has come to be called many different colloquial names over time such as: box, guit-fiddle and axe. The pitch bend arm found on many electric guitars has also had slang terms applied to it, such as "tremolo bar", "sissy bar", "whammy handle", and "whammy bar". The latter two slang terms led stompbox manufacturers to use the term 'whammy' in coming up with a pitch raising effect introduced by popular guitar brand "Digitech".
Interestingly, Leo Fender, who did so much to revolutionize the modern electric guitar, also created much confusion over the meaning of the terms "tremolo" and "vibrato", specifically by mis-naming the "tremolo" bar on his guitars and also regarding the "Vibrolux" amps. Vibrato is a variation in pitch, whereas tremolo is a variation in volume, so the tremolo bar is actually a vibrato bar and the "Vibrolux" amps actually had a tremolo effect.
A capo (used to change key without changing fingering) is sometimes called a "cheater".
A Slide, (bottle or knife) used in blues and rock to create a 'gliss' or 'hawaiian' effect. Many times, the necks of bottles were used, thus creating the term "bottle-neck".
A guitar/synthesizer is the adaptation of a guitar to control a synthesizer. Most commonly, a guitar/synth is a converter which analyzes the pitch of each string and sends an electronic message to a synthesizer, telling it what note to play. The pitches of the individual strings can be determined if a hexaphonic pickup is used. In modern implementations, the converter's output is a MIDI signal. This implementation led to the use of MIDI guitar as a synonym for a guitar/synthesizer or for the field of guitar synthesis in general.
A guitar-like MIDI controller is also refered to as a guitar/synthesizer. Such a device is not actually a guitar, but the human-interface is designed to play like one, allowing a guitarist to play a synthesizer or other MIDI-enabled instruments. The SynthAxe was one notable example.
One might also use the term guitar synthesis to refer to the field of programming synthesizers to sound like guitars, but this is far less common.