Guitar

History

The guitar is a stringed musical instrument. It is generally played with the fingers of the left hand. 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 have a 'body' (hollow in acoustic guitars, solid in most electric guitars) and a 'neck'. Typically, a 'headstock' extends from the neck for tuning. Like almost any kind of string instrument guitars may be acoustic, electric (ie. with electrical amplification) or both. Guitars are used in a variety of musical styles. They are made and repaired by luthiers.

History

Stringed instruments analogous to the guitar have been popular for at least 5,000 years. While today's classical guitar first emerged in Spain, it had been itself a product of the extensive as well as convoluted history that witnessed a number of consanguine guitar varieties developed and utilized throughout Europe. The origins of the guitar can be delineated back thousands of years to an Indo-European precursor in instrumentation, then perceived in central Asia and northern India. The oldest recognized iconographic depiction of an instrument exhibiting all the prerequisite components of a guitar being strummed is a 3,300 year old granite relief of a Hittite bard. The contemporary term, guitar, was assimilated into English from Spanish guitarra (German Gitarre, French Guitare), borrowed from the medieval Andalusian Arabic qitara, itself derived from the Latin cithara, which in turn derived from the preceding Greek word kithara.

The modern guitar is descended from the Roman cithara conveyed by the Roman settlers to Hispania around 40 AD, and further modified and developed with the later appearance of the four-string oud, produced by the Moors. Elsewhere in Europe, the indigenous six-string Scandinavian lut (lute), had increased in preeminence in regions of Viking incursions across the continent. By 1200 AD, the four string 'guitar' had evolved into two types: the guitarra morisca (Moorish guitar) which had a curved back, broad fingerboard and numerous soundholes, and the guitarra latina (Latin guitar) which approximated the modern guitar with one soundhole and a narrower neck.

The Spanish vihuela appears to be an intermediate construct between the precursory guitar and the modern guitar, with lute-style tuning and a compact guitar-style form, but it is not incontrovertible whether this represents a transitional design or simply a model that blended elements from the two families of musical instruments.

The electric guitar was invented by Adolf Rickenbacker, with the assistance of George Beauchamp and Paul Berth, in 1931. Rickenbacker 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.

Parts of the guitar

Headstock

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 etc

Nut

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.

Fretboard

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 noticeably 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

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.

Truss rod

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

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, 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, coloured 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 colouring (which involves black colouring 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.

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.

Neck

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.

Neck joint

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.

Body (acoustic guitar)

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, cedar 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.

Body (electric guitar)

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.

Resonating chamber

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.

Pickups

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 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-canceling 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.

Electronics

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.

Purfling and Binding

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.

Bridge

The main purpose of the bridge on an acoustic guitar is the 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.

Pickguard

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.

Strings and tuning

Strings

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 ${\sqrt[{12}]{2}}$, 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.

Tuning

A variety of different tunings are used. The most common by far, known as 'standard tuning' (EADGBE), is as follows:

• sixth (lowest) string: E (a minor thirteenth below middle C—82.4Hz)
• fifth string: A (a minor tenth below middle C—110Hz)
• fourth string: D (a minor seventh below middle C—146.8Hz)
• third string: G (a perfect fourth below middle C—196.0Hz)
• second string: B (a minor second below middle C—246.92Hz)
• first (highest) string: E (a major third above middle C—329.6Hz)

Standard tuning has evolved to provide a good compromise of both simple fingering for many chords, and the ability to play common scales with minimal left hand movement. Additionally, the separation of all adjacent string pairs except one (G-B) by the same interval, a perfect fourth (equivalent to 5 frets' distance), yields a symmetry and intelligibility to fingering patterns in this tuning. The major third (four frets' distance) between the g and b strings, though undermining this clarity, facilitates the playing of many chords and scales as mentioned above and, more generally, provides some diversity in fingering possibilities; many figures which are difficult to play on strings tuned a fourth apart are easy to play on strings tuned a third apart and vice versa.

Some common alternate tunings:

• E-A-d-f#-b-e which provides the same intervals as for a renaissance lute and so you can play with your guitar directly from tablature.
• D-G-d-g-b-d, open g tuning commonly used for blues or slide guitar
• Open D tuning D-A-d-f#-a-d, commonly used in blues and folk
• E-B-e-g#-b-e, open e tuning one step up from open D
• C-G-c-g-c'-e', open c tuning commonly used in country blues and by modern acoustic fingerstylists
• D-A-d-g-b-e', the drop d tuning frequently used in folk music, and by metal and alternative-rock bands
• E-a-d-g-c'-f', all fourths tuning removes from the standard tuning the irregularity of the interval of a third between the fourth and fifth strings. The tuning is in fourths like that of the lowest four strings in standard tuning. With regular tunings like this, chords can simply be moved down or across the fretboard, dramatically reducing the number of different finger positions that need to be memorized. The disadvantage of all fourths is that not all major and minor chords can be played with all six strings at once.
• C-G-d-a'-e'-b', all fifths tuning is in fifths like that of a mandolin or a violin and has a remarkably wide range.
• C-G-d-a-e-g, the new standard tuning used by most Guitar Craft students around the world. The tuning is like all fifths except the most treble string is dropped down from b' to g.
• D-A-d-g-a-d' frequently used in Celtic music, and by artists such as Pierre Bensusan.
• E-G#-C-e-g#-c, major third guitar tuning devised in 1960's by jazz guitarist Ralph Patt

Each of the six strings can be alternately tuned, as low as a whole step lower, to 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 16,575 possible tunings for a six-string guitar.

Note that a standard guitar sounds one octave below pitch as written in standard notation. Therefore, the pitch of the top string in standard tuning actually sounds as a major third above middle C, despite being written 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 normal guitar, treble guitars tuned a fourth higher than a standard (prime) guitar, and contrabass guitars, which are tuned one octave lower than prime guitars.

Acoustic and electric guitar

Broadly speaking, guitars can be divided into 2 major categories:

• Acoustic guitars:

Unlike the electric guitar, the traditional guitar is not dependent on any external device for amplification. The shape and resonance of the guitar itself creates acoustic amplification. However, the unamplified guitar is not a loud instrument, that is, it cannot compete with other instruments commonly found in bands and orchestras, in terms of sheer audible volume. Many acoustic guitars are available today with built-in electronics to enable amplification. There are several subcategories within the acoustic guitar group: classical and flamenco guitars, both of which use nylon and composite strings, and steel string guitars, which includes the flat top, or 'folk' guitar, the closely related twelve string guitar, and the arch top guitar. A recent arrival in the acoustic guitar group is the acoustic bass guitar, similar in tuning to the electric bass.

• Electric guitars:

Electric guitars can have solid, semi-hollow or hollow bodies, and produce little or very low sound without amplification. Electromagnetic pickups (single and double coil) convert the vibration of the steel strings into electric signals which are fed to an amplifier through a cable or radio device. The sound is frequently modified by other electronic devices or natural distortion of valves (vacuum tubes) in the amplifier. The electric guitar is used extensively in blues and rock and roll, and was commercialised by Gibson together with Les Paul and independently by Leo Fender. The lower fretboard action (the height of the strings from the fingerboard) and its electrical amplification lend the electric guitar to some techniques which are harder (or impossible) to execute on acoustic guitars. These techniques include tapping, extensive use of legato through pull-offs and hammer-ons (aka slurs in the traditional Classical genre), pinch harmonics, volume swells and use of a Tremolo arm or effects pedals.

Other guitar types include:

• Renaissance and Baroque guitars:

These are the gracile ancestors of the modern classical guitar. They are substantially smaller and more delicate than the classical guitar, and generate a much quieter sound. The strings are paired in courses as in a modern 12 string guitar, but they only have four or five courses of strings rather than six. They were more often used as rhythm instruments in ensembles than as solo instruments, and can often be seen in that role in early music performances. (Gaspar Sanz' Instrucción de Música sobre la Guitarra Española of 1674 constitutes the majority of the surviving solo corpus for the era.) Renaissance and Baroque guitars are easily distinguished because the Renaissance guitar is very plain and the Baroque guitar is very ornate, with inlays all over the neck and body, and a paper-cutout inverted 'wedding cake' inside the hole.

• Classical guitars:

These are typically strung with nylon strings, played in a seated position and used to play classical music. Flamenco guitars are almost equal in construction, have a sharper sound, and are used in flamenco. In Mexico, the popular mariachi band includes a range of guitars, from the tiny requinto to the guitarron, a guitar larger than a cello, which is tuned in the bass register. The father of the modern classical guitar was Antonio Torres Jurado.

• Flat top guitars:

Similar to the classical guitar, however the body size is usually significantly larger than a classical guitar and it has a narrower, reinforced neck and stronger structural design, to sustain the extra tension of steel strings which produce a louder and brighter tone. The acoustic guitar is a staple in folk, Old-time music and blues music.

• Resonator, resophonic or Dobro^® guitars:

Similar to the flat top guitar in appearance, but with sound produced by a metal resonator mounted in the middle of the top rather than an open sound hole, so that the physical principle of the guitar is actually more similar to the banjo. The purpose of the resonator is to amplify the sound of the guitar; this purpose has been largely superseded by electrical amplification, but the resonator is still played by those desiring its distinctive sound. The type of resonator guitar with a neck with a square cross-section -- called 'square neck' -- is usually played face up, on the lap of the seated player, and often with a metal or glass slide. The round neck resonator guitars are normally played in the same fashion as other guitars, although slides are also often used, especially in blues.

• 12 string guitars:

Usually have steel strings and are widely used in folk music, blues and rock and roll. Rather than having only six strings, the 12-string guitar has pairs, like a mandolin. Each pair of strings is tuned either in unison (the two highest) or an octave apart (the others). They are made both in acoustic and electric forms. Big Joe Williams is a a blues musician famous for his 12 string guitar.

• Archtop guitars:

Steel string, instruments which feature a violin-inspired f-hole design in which the top (and often the back) of the instrument are carved in a curved rather than a flat shape. Lloyd Loar of the Gibson Guitar Corporation invented this variation of guitar after designing a style of mandolin of the same type. The typical Archtop is a hollow body guitar whose form is much like that of a mandolin or violin family instrument and may be acoustic or electric. Some solid body electric guitars are also considered archtop guitars although usually 'Archtop guitar' refers to the hollow body form. Archtop guitars were immediately adopted upon their release by both jazz and country musicians and have remained particularly popular in jazz music, usually using thicker strings (higher gauged round wound and flat wound) than acoustic guitars. Archtops are often louder than a typical dreadnought acoustic guitar. The electric hollow body archtop guitar has a distinct sound among electric guitars and is consequently appropriate for many styles of rock and roll. Many electric archtop guitars intended for use in rock and roll even have a Tremolo arm.

• Acoustic bass guitars:

Have steel strings, and match the tuning of the electric bass, which is likewise similar to the traditional double bass viol, the 'big bass', a staple of string orchestras and bluegrass bands alike.

• Harp Guitars:

Guitars that are difficult to classify as there are many variations within this type. They are typically rare and uncommon in the popular music scene. Most consist of a regular guitar, plus additional 'harp' strings strung above the six normal strings. The instrument is usually acoustic and the harp strings are usually tuned to lower notes than the guitar strings, for an added bass range. Normally there is neither fingerboard nor frets behind the harp strings. Some harp guitars also feature much higher pitch strings strung below the traditional guitar strings. The number of harp strings varies greatly, depending on the type of guitar and also the player's personal preference (as they have often been made to the player's specification).

• 7 string guitars:

Developed in the 1990s (earlier in jazz) to achieve a much darker sound through extending the lower end of the guitar's range. Some guitarists go a step further, using an 8 string guitar with two extra low strings.

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.

Guitar terminology

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', '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. On Fender products these effects do the opposite. 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.

Guitar/synthesizer

A guitar/synthesizer is the adaptation of a guitar to control a synthesizer. Most commonly, a guitar/synth is a converter which analyses 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 referred 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.