History of the Guitar
Before the development of the electric guitar and the use of synthetic materials, a guitar was defined as being a musical instrument having "a long, fretted neck, flat wooden soundboard, ribs, and a flat back, most often with incurved sides". Instruments similar to the guitar have been popular for at least 5,000 years. The oldest known graphic representation of an instrument displaying all the essential features of a guitar being played is a 3,300 year old stone carving of a Hittite minstrel.
The modern guitar owes its development to three separate influences, one being the Roman "Cithara" brought by the Romans to Spain around 40 AD, the second influence being the arrival of the four-string "Oud", (Arabic, meaning wood), brought by the Moors after their conquest of the Iberian peninsula in the 8th century, and the third influence being the six-string Scandinavian "Lut" , (lute), introduced through the Viking incursions across the continent. The cithara was an ancient Greek musical instrument in the zither family, it was a version of the seven-stringed lyre that was primarily used by the "professional" musicians of the time. The simpler lyre was primarily a folk-instrument. The oud usually had five strings made of gut. The neck of the oud, which is short in comparison to the body, has no frets and this contributes to its unique sound. The most common string combination is five pairs of strings tuned in unison and a single bass string. Another distinctive feature of the oud is its head, with the tuning pegs bent back at an angle to the neck. The oud was quickly adopted by the Europeans after its introduction.
The lute held the highest respect of all the musical instruments during the Renaissance period. Its basic design is similar to the oud, with the main difference being that it had frets. Lutes are made almost entirely of wood. The soundboard is a teardrop-shaped thin flat plate of resonant wood (usually spruce). In all lutes the soundboard has a single (sometimes triple) decorated sound hole under the strings, called the rose. The lute also featured 6 pairs of strings, although sometimes the top string was single. Among other predecessors of the guitar were the Spanish "Vihuela" , resembling a guitar although larger with six or seven courses, (strings), paired in unison as in the lute. The Romanian "Cobza" , a short necked, un-fretted lute very similar to the oud of Iraq, and Syria., and the "Mandolin", A small lute-like instrument with a typically pear-shaped body and a straight fretted neck, having usually four sets of paired strings tuned in unison or octaves.
By the 13th century the four string "guitar" had evolved into two types: the guitarra morisca, (Moorish guitar), which had a rounded back, wide fingerboard and several sound holes, and the guitarra latina, (Latin guitar), which resembled the modern guitar with one sound hole and a narrower neck.The number of strings became variable, from three to four to five. However, by the end of the medieval period, the four string guitar emerged as the most popular.
During the 16th century, another string was added creating the five string guitar. The tuning of the five string guitar was A - D - G - B - E, as on the first five strings of the modern guitar. The A string was the addition to the four string guitar. This five string guitar emerged from Italy and gained acceptance throughout Europe. These influences led to the vihuela, which had 6 pairs of strings and due to its many similarities is considered to be the immediate ancestor of the modern guitar. It had lute-style tuning and a guitar-like body. Its construction had as much in common with the modern guitar as with its contemporary four-course renaissance guitar. The vihuela enjoyed only a short period of popularity as it was superseded by the guitar. It is not clear whether it represented a transitional form or was simply a design that combined features of the Arabic oud and the European lute.
Undoubtedly the most important factor in the development of the guitar was the addition of the sixth string. This development can be credited to 18th century Italy as the Italian guitarra battente had an arrangement of six pair of strings. The precise date six single strings replaced six double strings is not known, but toward the end of the 18th century, the guitar with six single strings overshadowed all other types. The rosette gave way to an open sound hole, while the neck was lengthened and fitted with a raised fingerboard extending to the sound hole. Nineteen fixed metal frets eventually became standard. The bridge was raised, the body enlarged, and fan-strutting introduced beneath the sound board to support higher tension strings. Treble strings were made of gut, which was replaced by more durable nylon after World War II and eventually steel on the modern day flat top.
The Vinaccia family of luthiers is known for developing the mandolin, and may have built the oldest surviving six string guitar. Gaetano Vinaccia has his signature on the label of a six string guitar built in Naples, Italy with the date of 1779.
The dimensions of the modern classical guitar (also known as the Spanish guitar) were established by Antonio Torres Jurado , working in Seville in the 1850s. Torres and Louis Panormo of London were both responsible for demonstrating the superiority of fan strutting over transverse table bracing. Antonio de Torres worked with the design and construction of the guitar. Up until this point the guitar was small and narrow. He increased the size and experimented with improving the sound, and was especially interested in volume. He was the first builder to use "fan" bracing in the top. To prove his theory that the top produced most of the volume he designed and built a guitar with a spruce top and Paper Mache´ back and sides. He is the father of the guitar as we know it today.
There are several types of guitars in use today, each having its own niche based on design, playability, and sound qualities.
Acoustic Guitar - The Acoustic guitar is not dependent on an external device to be heard but uses a soundboard which is a wooden piece mounted on the front of the guitar's body. The acoustic guitar is quieter than other musical instruments commonly found in bands and orchestras so when playing within such groups it is often externally amplified. Many acoustic guitars available today feature a variety of pickups which enable the player to amplify and modify the raw guitar sound. There are several notable subcategories within the acoustic guitar group: classical and flamenco guitars; steel string guitars, which include the flat top or "folk" guitar; twelve string guitars and the arch top guitar. The acoustic guitar group also includes un-amplified guitars designed to play in different registers such as the acoustic bass guitar which has a similar tuning to that of the electric bass guitar.
Classical Guitar - The Classical guitars are typically strung with nylon strings, played in a seated position and are used to play a diversity of musical styles including classical music. The classical guitar is designed to allow for the execution of solo polyphonic arrangements of music. Flamenco guitars are very similar in construction, but are associated with a more percussive tone. 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.
Flat Top Guitar - The Flat-top (steel-string) guitar is 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. This allows the instrument to withstand the additional tension of steel strings. The steel strings produce a brighter tone, and according to many players, a louder sound. The acoustic guitar is used in many kinds of music including folk, country, bluegrass,pop, jazz and blues.
Arch-top Guitar - The Archtop guitars are steel string instruments which feature a violin-inspired f-hole design in which the top is carved into 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 deep, hollow body guitar whose form is much like that of the mandolin or violin family of musical instruments and may be acoustic or electric. Some solid body electric guitars are also considered arch-top guitars although usually Arch-top guitar' refers to the hollow body form. Arch-top guitars were immediately adopted upon their release by both jazz and country musicians and have remained particularly popular in jazz music, usually with flat wound strings. The electric semi-hollow body arch-top guitar has a distinct sound among electric guitars and is consequently appropriate for many styles of pop music. Many electric arch-top guitars intended for use in rock and roll have a Tremolo Arm.
Resonator Guitar - The Resonator, resophonic or Dobro guitars are similar to the flat top guitar in appearance, the sound of the resonator guitar is produced by a metal resonator mounted in the middle of the top. The physical principle of the guitar is therefore similar to the banjo. The original purpose of the resonator was to amplify the sound of the guitar. This purpose has been largely superseded by electrical amplification, but the resonator guitar is still played because of its distinctive sound. Resonator guitars may have either one resonator cone or three resonator cones. Three-cone resonators have two cones on the left above one another and one cone immediately to the right. The method of transmitting sound resonance to the cone is either a "biscuit" bridge, made of a small piece of hardwood, or a "spider" bridge, made of metal and larger in size. Three-cone resonators always use a specialized metal spider bridge.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.
Twelve Sting Guitar - The 12 string guitar usually has steel strings and is widely used in folk music, blues and rock and roll. Rather than having only six strings, the 12 string guitar has six courses made up of two strings each, like a mandolin or lute. The highest two courses are tuned in unison, while the others are tuned in octaves. The 12 string guitar is also made in electric forms.
Seven String Guitar - These are seven string acoustic guitars which were the norm for Russian guitarists throughout the 19th and well into the 20th centuries. The guitar is traditionally tuned to an open G major tuning.
Tenor Guitars - Tenor guitars are generally a 4-string guitar with a scale length of 23"and are tuned in fifths, C G D A, as is the tenor banjo and the cello. It is generally accepted that the tenor guitar was created to allow a tenor banjo player to follow the fashion as it evolved from Dixieland Jazz towards the more progressive Jazz that featured guitar. It allows a tenor banjo player to provide a guitar-based rhythm section with little to learn.
Harp Guitars - Harp Guitars are difficult to classify as there are many variations within this type of guitar. 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 musical 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.
Electric Guitars - Electric guitars can have solid, semi-hollow, or hollow bodies, and produce little sound without amplification. Electromagnetic pickups convert the vibration of the steel strings into electrical signals which are fed to an amplifier through a cable or radio transmitter. The sound is frequently modified by other electronic devices or the natural distortion of valves (vacuum tubes) in the amplifier. There are two main types of pickup, single and double coil (or humbucker), each of which can be passive or active. The electric guitar is used extensively in jazz, blues, and rock and roll, and was commercialized by Gibson in collaboration with Les Paul, and independently by Leo Fender of Fender Music. The lower fret board action (the height of the strings from the fingerboard) and its electrical amplification lend the electric guitar to some techniques which are less frequently used on acoustic guitars. These include tapping, extensive use of legato through pull-offs and hammer-ons (also known as slurs), pinch harmonics, volume swells, and use of a tremolo arm or effects pedals.
Electric Bass Guitars - The electric bass guitar 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 guitars with two, three, or rarely four necks, all manner of alternate string arrangements, fret less fingerboards used almost exclusively on bass guitars and are meant to emulate the sound of a stand-up bass.
The development of the solid body (electric) guitar owes a great deal to the popularity of Hawaiian music in the early 1900’s. Hawaiian guitars were solo instruments played with a metal slide. Electric Hawaiian guitars were the first instruments that depending entirely on their sound being amplified.
A key figure in the early designs of the electric guitar history was Adolph Rickenbacker who originally made metal components for The Dopera Brothers' National Resonator Guitars. While at National Resonator, Rickenbacker teamed up with George Beauchamp and Paul Barth who had been working together on the magnetic pick-up. Together they formed the Electro String Company and in 1931 produced their first Hawaiian guitars. Their success prompted Gibson and others to start making electric guitars.
In the 1940s Gibson became firmly established as a manufacturer of electric guitars. People began to work on ways of applying the solid body of the Hawaiian and steel guitars to regular instruments. In 1944, Leo Fender, who ran a radio repair shop, teamed up with Doc Kaufman, and started The K & F Company producing a series of steel guitars and amplifiers. Leo Fender felt the pickups being used at the time were excessively large and designed a newer version, and incorporated it into a guitar with a more properly fretted fingerboard. The guitar was only meant to demonstrate this new pickup but soon became in such demand that the Fender Electric Instrument company was born in 1946. Fender was more concerned with practical usage rather then appearance and wanted a regular guitar with the clear sound of the Hawaiian electric of the period but, without the feedback problems The result was the Broadcaster which he began producing in 1948 and later was renamed the Telecaster.
Les Paul was working in this same direction by experimenting with pick ups throughout the 1930s but, because of feedback and resonance problems he began to think about a solid body guitar. He was convinced that the only way to avoid feedback was to reduce pick up movement by mounting it in a solid body. Les persuaded Epiphone to let him experiment in their shop, where in 1941 he built the historic "log" guitar
In 1947 Paul Bigsby in concert with Merle Travis built a solid body electric guitar that shared some of the design features of the Broadcaster that Fender introduced in 1948. Fender was more concerned with utility and practicality rather then looks and wanted a regular guitar with the clear sound of the electric Hawaiian but, without the feedback problems. The result was the Broadcaster which he began producing in 1948 later renamed the Telecaster. In 1954, Fender began producing the Stratocaster, and along with the Telecaster and the Gibson Les Paul models, the standard was set for solid body guitars.
Through a myriad on new design and innovation Fender and Gibson continue to be the “Big Boys” in the electric guitar industry.
Guitars can be constructed to meet the demands of both left and right-handed players. Traditionally the dominant hand is assigned the task of plucking or strumming the strings. For the majority of people this entails using the right hand. This is because musical expression (dynamics, tonal expression and color etc) is largely determined by the plucking hand, while the fretting hand is assigned the lesser mechanical task of depressing and gripping the strings. This is similar to the convention of the violin family of instruments where the right hand controls the bow. A minority, however, believe that left-handed people should learn to play guitars strung in the manner used by right-handed people, simply to standardize the instrument.
The Head Stock is located at the end of the guitar neck furthest from the body. It is fitted with machine heads that adjust the tension of the strings, which in turn affects the pitch. Traditional tuner layout is "3+3" in which each side of the head stock has three tuners (such as on Gibson Les Pauls). In this layout, the head stocks are commonly symmetrical. Many guitars feature other layouts as well, including six-in-line (featured on Fender Stratocasters) tuners or even "4+2" (Ernie Ball Music Man). However, some guitars (such as Steinbergers) do not have head stocks at all, in which case the tuning machines are located elsewhere, either on the body or the bridge.
The Nut is a small strip of bone, plastic, brass, corian, graphite, stainless steel, or other medium-hard material, at the joint where the head stock meets the fret board. Its grooves guide the strings onto the fret board., giving consistent lateral string placement. It is one of the endpoints of the strings' vibrating length. It must be accurately cut, or it can contribute to tuning problems due to string slippage, and/or string buzz.
Also called the fingerboard, the Fret Board is a piece of wood embedded with metal frets that comprises the top of the neck. It is flat on classical guitar construction and slightly curved crosswise on acoustic and electric guitars. The curvature of the fret board. is measured by the fret board. radius, which is the radius of a hypothetical circle of which the fret board.'s surface constitutes a segment. The smaller the fret board. radius, the more noticeably curved the fret board. is. Most modern guitars feature a 12" neck radius, while older guitars from the '60's and '70's usually feature a 6" – 8" neck radius. Pinching a string against the fret board. effectively shortens the vibrating length of the string, producing a higher pitch. Fret boards are most commonly made of rosewood, ebony, maple, and sometimes manufactured or composite materials such as HPL or resin.
Frets are metal strips (usually nickel alloy or stainless steel) embedded along the fret board. and located at exact points that divide the scale length in accordance with a specific mathematical formula. Pressing a string against a fret determines the strings' vibrating length and therefore its resultant pitch. The pitch of each consecutive fret is defined at a half-step interval on the chromatic scale. Standard classical guitars have 19 frets and electric guitars between 21 to 24 frets.
The Truss Rod is a metal rod that runs along the inside of the neck. It is used to correct changes to the neck's curvature caused by the neck timbers aging, changes in humidity or to compensate for changes in the tension of strings. The tension of the rod and neck assembly is adjusted by a hex nut or an allen-key bolt on the rod, usually located either at the head stock, sometimes under a cover, or just inside the body of the guitar underneath the fret board. and accessible through the sound hole. Some truss rods can only be accessed by removing the neck. The truss rod counteracts the immense amount of tension the strings place on the neck, bringing the neck back to a straighter position. Turning the truss rod clockwise will tighten it, counteracting the tension of the strings and straightening the neck or creating a backward bow. Turning the truss rod counter-clockwise will loosen it, allowing string tension to act on the neck and creating a forward bow. Adjusting the truss rod affects the intonation of a guitar as well as the height of the strings from the fingerboard, called the action. Classical guitars do not require truss rods as their nylon strings exert a lower tensile force with lesser potential to cause structural problems.
Inlays are visual elements set into the exterior surface of the guitar construction. The typical locations for inlay are on the fret board., head stock, and on acoustic guitars around the sound hole, known as the rosette. Inlays range from simple plastic dots on the fret board. to intricate works of art covering the entire exterior surface of a guitar. Some guitar players have used LEDs in the fret board. to produce a unique lighting effects onstage. Fret board. 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 fret board. in the same positions, small enough to be visible only to the player. Some older or high-end instruments have inlays made of mother of pearl, abalone, ivory, colored wood or other exotic materials and designs. Simpler inlays are often made of plastic or painted. High-end classical guitars seldom have fret board. inlays as a well trained player is expected to know his or her way around the instrument. In addition to fret board. inlay, the head stock and sound hole surround are also frequently inlaid. The manufacturer's logo or a small design is often inlaid into the head stock Rosette designs vary from simple concentric circles to delicate fretwork mimicking the historic rosette of lutes. Bindings that edge the finger and sound boards are sometimes inlaid. Some instruments have a filler strip running down the length and behind the neck, used for strength and/or to fill the cavity through which the truss rod was installed in the neck. Elaborate inlays are a decorative feature of many limited edition, high-end and custom-made guitars. Guitar manufacturers often release such guitars to celebrate significant or historic milestones.
A guitar's frets, fret board., tuners, head stock, and truss rod, all attached to a long wooden extension, collectively constitute its Neck. The wood used to make the fret board. 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 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. The shape of the neck can also vary, from a gentle "C" curve to a more pronounced "V" curve. There are many different types of neck profiles available, giving the guitarist many options. Some aspects to consider in a guitar neck may be the overall width of the fingerboard, scale (distance between the frets), the neck wood, the type of neck construction (for example, the neck may be glued in or bolted on), and the shape (profile) of the back of the neck. Other type of material used to make guitar necks are graphite (Steinberger guitars), aluminum (Kramer Guitars, Travis Bean and Veleno guitars), or carbon fiber (Modulus Guitars and Three Guitars).
Neck joint or 'Heel' 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 (otherwise known as set) necks, while electric guitars are constructed using both types. Commonly used set neck joints include mortise and tenon joints (such as those used by CF Martin & Co. guitars), dovetail joints (also used by CF Martin on the D28 and similar models) and Spanish heel neck joints which are named after the shoe they resemble and commonly found in classical guitars. All three types offer stability. 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. Another type of neck, only available for solid body electric guitars, is the neck-through-body construction. These are designed so that everything from the machine heads down to the bridge are located on the same piece of wood. The sides (also known as wings) of the guitar are then glued to this central piece. Some luthier's prefer this method of construction as they claim it allows better sustain of each note. Some instruments may not have a neck joint at all, having the neck and sides built as one piece and the body built around it.
Modern Guitar Strings are manufactured in either metal or organo-carbon material. Instruments utilizing "steel" strings may have strings made of alloys incorporating steel, nickel or phosphor bronze. Classical and flamenco instruments have historically used gut strings but these have been superseded by nylon and carbon-fibre materials. Bass strings for both instruments are wound rather than monofilament. Guitar strings are strung almost parallel to the neck, whose surface is covered by the fingerboard (fret board.). By depressing a string against the fingerboard, the effective length of the string can be changed, which in turn changes the frequency at which the string will vibrate when plucked. Guitarists typically use one hand to pluck the strings and the other to depress the strings against the fret board. In acoustic guitars, string vibration is transmitted through the bridge and saddle to the body via sound board.
The Sound Board is typically made of tone woods such as spruce or cedar. Timbers for tone woods are chosen for both strength and ability to transfer mechanical energy from the strings to the air within the guitar body. Sound is further shaped by the characteristics of the guitar body's resonant cavity. In electric guitars, transducers known as pickups convert string vibration to an electric signal, which in turn is amplified and fed to speakers, which vibrate the air to produce the sound we hear. Nevertheless, the body of the electric guitar still performs a role in shaping the resultant tonal signature.
In acoustic guitar construction, the body of the guitar is a major determinant of the overall sound quality. The guitar top, or sound board, is a finely crafted and engineered element made of tone woods such as spruce and red cedar. This thin piece of wood, often only 2 or 3mm thick, is strengthened by differing types of internal bracing. The top is considered by many luthier's to be the dominant factor in determining the sound quality. The majority of the instrument's sound is heard through the vibration of the guitar top as the energy of the vibrating strings is transferred to it.
Body size, shape and style has changed over time. 19th century guitars, now known as salon guitars, were smaller than modern instruments. Differing patterns of internal bracing have been used over time by luthier's. Torres, Hauser, Ramirez, Fleta, and C.F. Martin were among the most influential designers of their time. Bracing not only strengthens the top against potential collapse due to the stress exerted by the tensioned strings, but also affects the resonance characteristics of the top. The back and sides are made out of a variety of timbers such as mahogany, Indian rosewood and highly regarded Brazilian rosewood (Dalbergia nigra). Each one is primarily chosen for their aesthetic effect and can be decorated with inlays and purfling.
The body of an acoustic guitar has a sound hole through which sound is projected. The sound hole is usually a round hole in the top of the guitar under the strings. Air inside the body vibrates as the guitar top and body is vibrated by the strings, and the response of the air cavity at different frequencies is characterized, like the rest of the guitar body, by a number of resonance modes at which it responds more strongly.
Instruments with larger areas for the guitar top were introduced by Martin in an attempt to create louder volume levels. The popularity of the larger "dreadnought" body size amongst acoustic performers is related to the greater sound volume produced.
Most electric guitar bodies are made of wood and include a plastic pick guard. Boards wide enough to use as a solid body are very expensive due to the worldwide depletion of hardwood stock since the 70's, so the wood is rarely one solid piece. Most bodies are made of two pieces of wood with some of them including a seam running down the center line of the body. 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. Most electrics have a polyurethane or nitrocellulose lacquer finish. Other alternative materials to wood, are used in guitar body construction. Some of these include carbon composites, plastic material (such as polycarbonate) and aluminum alloys.
Pickups are transducers attached to a guitar that detect (or "pick up") string vibrations and convert the mechanical energy of the string into electrical energy. The resultant electrical signal can then be electronically amplified. The most common type of pickup is electromagnetic in design. These contain magnets that are tightly wrapped in a coil, or coils, of copper wire. Such pickups are usually placed right underneath the guitar strings. Electromagnetic pickups work on the same principles and in a similar manner to an electrical generator. The vibration of the strings causes a small voltage to be created in the coils surrounding the magnets, this signal voltage is later amplified. Traditional electromagnetic pickups are either single-coil or double-coil. Single coil pickups are susceptible to noise induced from electric fields, usually mains-frequency (60 or 50 hertz) hum. The introduction of the double-coil humbucker in the mid-50's did away with this problem through the use of two coils, one of which is wired in a reverse polarity orientation.The type and model of pickups used can greatly affect the tone of the guitar. Typically, humbuckers, which are two magnet/coil assemblies attached to each other are traditionally associated a heavier sound. Single coil pickups, one magnet wrapped in copper wire, are used by guitarists seeking a brighter, twangy-er sound with greater dynamic range. Modern pickups are tailored to the sound desired. A commonly applied approximation used in selection of pickup is that less wire (lower dc resistance) = brighter sound, more wire = "fat" tone. Other options include specialized switching that produces coil-splitting, in/out of phase and other effects. Guitar circuits are either active, needing a battery to power their circuit, or, as in most cases, equipped with a passive circuit. Fender Stratocaster type guitars generally utilize 3 single coil pickups, while most Gibson Les Paul types use humbucker pickups.
Piezoelectric, or piezo, pickups represent another class of pickup. These employ piezoelectricity to generate the musical signal and are popular in hybrid electro-acoustic guitars. A crystal is located under each string, usually in the saddle. When the string vibrates, the shape of the crystal is distorted, and the stresses associated with this change produce tiny voltages across the crystal that can be amplified and manipulated.
Some piezo equipped guitars use what is known as a hex- aphonic pickup. "Hex" is a prefix meaning six. In a hex-aphonic pickup separate outputs are obtained from discrete piezoelectric pickups for each of the six strings. This arrangement allows the signal to be easily modified by on-board modeling electronics, as in the Line 6 Variax brand of electric guitars, the guitars allow for a variety of different sounds to be obtained by digitally manipulating the signal. This allows a guitar to mimic many vintage models of guitar, as well as output alternate tunings without the need to adjust the strings. Another use for hex-aphonic pickups is to send the output signals to a MIDI interpretation device, which determines the note pitch, duration, attack and decay characteristics and so forth. The MIDI (Musical Instrument Digital Interface) interpreter then sends the note information to a sound bank device. The resulting sound can closely mimic numerous types of instrument.
On guitars that have them, the electronic 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 pre-amplification and signal processing, or even for assistance in tuning. In many cases the electronics have some sort of shielding to prevent pickup of external interference and noise.
The top, back and ribs of an acoustic guitar body are very thin (1-2 mm), so a flexible piece of wood called lining is glued into the corners where the rib meets the top and back. This interior reinforcement provides 5 to 20 mm of solid gluing area for these corner joints. Solid linings are often used in classical guitars, while kerfed lining is most often found in steel string acoustics. Kerfed lining is also called kerfing (because it is scored, or kerfed to allow it to bend with the shape of the rib). During final construction, a small section of the outside corners is carved or routed out and then filled with binding material on the outside corners and decorative strips of material next to the binding, which are called Purfling. This binding serves to seal off the end grain of the top and back. Purfling can also appear on the back of an acoustic guitar, marking the edge joints of the two or three sections of the back. Binding and purfling materials are generally made of either wood or plastic.
The main purpose of the Bridge, (which supports the saddle), 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 on the body. There are many varied bridge designs. There may be some mechanism for raising or lowering the bridge to adjust the distance between the strings and the fret board (action), and/or fine-tuning the intonation of the instrument. Some are spring-loaded 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 also referred to as a "tremolo bar" (see Tremolo for further discussion of this term – the effect of rapidly changing pitch produced by a whammy bar is more correctly called "vibrato"). Some bridges also allow for alternate tunings at the touch of a button. On almost all modern electric guitars, the bridge is adjustable for each string so that intonation stays correct up and down the neck. If the open string is in tune but sharp or flat when frets are pressed, the bridge can be adjusted with a screwdriver or hex key to remedy the problem. In general, flat notes are corrected by moving the bridge forward and sharp notes by moving it backwards. On an instrument correctly adjusted for intonation, the actual length of each string from the nut to the bridge saddle will be slightly but measurably longer than the scale length of the instrument. This additional length is called compensation, which flattens all notes a bit to compensate for the sharping of all fretted notes caused by stretching the string during fretting.
The Pick- guard a also known as a scratch plate is usually a piece of laminated plastic or other material that protects the finish of the top of the guitar from damage due to the use of a plectrum or fingernails. Electric guitars sometimes mount pickups and electronics on the pick guard. It is a common feature on steel-string acoustic guitars. Vigorous performance styles such as flamenco, which can involve the use of the guitar as a percussion instrument, call for a scratch plate to be fitted to nylon-string instruments.
Tremolo arm or vibrato unit found on many electric guitars is commonly referred to as the "tremolo bar or "whammy bar" and it is used to lower or raise the pith of the played note.