Editing Guitar (section)

====Neck====
{{Unreferenced section|date=February 2020}}
{{Main|Neck (music)}}
{{See also|Fingerboard|Fret|Truss rod|Inlay (guitar)|Set-in neck|Bolt-on neck|Neck-through}}
A guitar's [[frets]], [[fretboard]], [[Machine head|tuners]], [[headstock]], and [[truss rod]], all attached to a long wooden extension, collectively constitute its [[neck (music)|neck]]. The wood used to make the fretboard usually differs 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|Tuning]]), and the ability of the neck to resist bending (see [[#Truss rod|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-quality one.

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| footer = ''Triple Neck'' (Left) and ''Double Neck'' (Right) Guitars.
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The cross-section 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 fretboard, 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 types of material used to make guitar necks are graphite ([[Steinberger]] guitars), aluminum ([[Kramer Guitars]], [[Travis Bean]] and [[Veleno (guitar)|Veleno guitars]]), or carbon fiber ([[Modulus Guitars]] and [[ThreeGuitars]]). [[Double neck guitars|Double neck]] electric guitars have two necks, allowing the musician to quickly switch between guitar sounds.

The 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 steel-string guitars, with the primary exception of Taylors, have glued (otherwise known as set) necks, while electric guitars are constructed using both types. Most classical guitars have a neck and headblock carved from one piece of wood, known as a "Spanish heel". Commonly used set neck joints include [[mortise and tenon]] joints (such as those used by C. F. Martin & Co.), dovetail joints (also used by C. F. Martin on the D-28 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 is located on the same piece of wood. The sides (also known as wings) of the guitar are then glued to this central piece. Some luthiers 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.

The [[fingerboard]], also called the fretboard, is a piece 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. Most modern guitars feature a 12" neck radius, while older guitars from the 1960s and 1970s usually feature a 6-8" neck radius. Pinching a string against a fret on the fretboard effectively shortens the vibrating length of the string, producing a higher pitch.

Fretboards are most commonly made of [[rosewood]], [[ebony]], [[maple]], and sometimes manufactured using composite materials such as HPL or resin. See the section "Neck" below for the importance of the length of the fretboard in connection to other dimensions of the guitar. The fingerboard plays an essential role in the treble tone for acoustic guitars. The quality of vibration of the fingerboard is the principal characteristic for generating the best treble tone. For that reason, ebony wood is better, but because of high use, ebony has become rare and extremely expensive. Most guitar manufacturers have adopted rosewood instead of ebony.

[[File:Sinéad O’Connor (cropped).jpg|thumb|[[Sinéad O'Connor]] playing a Fender guitar with a [[Capo (musical device)|capo]] ]]

=====Frets=====
Almost all guitars have frets, which are metal strips (usually nickel alloy or stainless steel) embedded along the fretboard and located at exact points that divide the scale length in accordance with a specific mathematical formula. The exceptions include [[fretless bass]] guitars and very rare fretless guitars. 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 and 24 frets, although guitars have been made with as many as 27 frets. Frets are laid out to accomplish an [[equal temperament|equal tempered]] division of the octave. Each set of twelve frets represents an octave. The twelfth fret divides the [[scale (string instruments)|scale length]] exactly into two halves, and the 24th fret position divides one of those halves in half again.

The [[ratio]] of the spacing of two consecutive frets is <math>\sqrt[12]{2}</math> ([[twelfth root of two]]). In practice, [[luthiers]] determine fret positions using the constant 17.817—an approximation to 1/(1-1/<math>\sqrt[12]{2}</math>). If the nth fret is a distance x from the bridge, then the distance from the (n+1)th fret to the bridge is x-(x/17.817).<ref name="Calculating Fret Positions">{{cite web |last=Mottola |first=R.M. |title=Lutherie Info—Calculating Fret Positions |url=http://www.liutaiomottola.com/formulae/fret.htm}}</ref> Frets are available in several different gauges and can be fitted according to player preference. Among these are "jumbo" frets, which have a much thicker gauge, allowing for use of a slight vibrato technique from pushing the string down harder and softer. "Scalloped" fretboards, where the wood of the fretboard itself is "scooped out" between the frets, allow a dramatic vibrato effect. Fine frets, much flatter, allow a very low [[Action (music)|string-action]], but require that other conditions, such as curvature of the neck, be well-maintained to prevent buzz.

=====Truss rod=====

The truss rod is a thin, strong metal rod that runs along the inside of the neck. It is used to correct changes to the neck's curvature caused by aging of the neck timbers, 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 headstock, sometimes under a cover, or just inside the body of the guitar underneath the fretboard 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 tightens it, counteracting the tension of the strings and straightening the neck or creating a backward bow. Turning the truss rod counter-clockwise loosens 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 (music)|action]]. Some truss rod systems, called ''double action'' truss systems, tighten both ways, pushing the neck both forward and backward (standard truss rods can only release to a point beyond which the neck is no longer compressed and pulled backward). The artist and [[luthier]] Irving Sloane pointed out, in his book ''Steel-String Guitar Construction'', that truss rods are intended primarily to remedy concave bowing of the neck, but cannot correct a neck with "back bow" or one that has become twisted.<ref>
{{cite book
 |last= Sloane
 |first= Irving 
 |date= 1975
 |title= Steel-string Guitar Construction: Acoustic Six-string, Twelve-string, and Arched-top Guitars
 |url=https://books.google.com/books?id=2sAXAQAAIAAJ&q=back+bow
 |location=
 |publisher=Dutton 
 |page= 45
 |isbn= 978-0-87-690172-4
}}
</ref> Classical guitars do not require truss rods, as their nylon strings exert a lower tensile force with lesser potential to cause structural problems. However, their necks are often reinforced with a strip of harder wood, such as an [[ebony]] strip that runs down the back of a [[Thuja plicata|cedar]] neck. There is no tension adjustment on this form of reinforcement.

=====Inlays=====
{{More sources needed section|date=September 2023}}
Inlays are visual elements set into the exterior surface of a guitar, both for decoration and artistic purposes and, in the case of the markings on the 3rd, 5th, 7th and 12th fret (and in higher octaves), to provide guidance to the performer about the location of frets on the instrument.<ref>{{Cite web |last=Reyes |first=Daniel |date=2023-07-03 |title=What Are The Dots On A Guitar Fretboard For? (2023) |url=https://www.guitarbased.com/what-are-the-dots-on-a-guitar-fretboard-for/ |access-date=2023-09-20 |website=Guitar Based |language=en-US}}</ref> The typical locations for inlay are on the fretboard, headstock, and on acoustic guitars around the soundhole, known as the [[rosette (design)|rosette]]. Inlays range from simple plastic dots on the fretboard to intricate works of art covering the entire exterior surface of a guitar (front and back). Some guitar players have used [[LED]]s in the fretboard to produce unique lighting effects onstage. 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. These usually appear on the odd-numbered frets, but also on the 12th fret (the one-[[octave]] mark) instead of the 11th and 13th frets. 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 fretboard inlays as a well-trained player is expected to know his or her way around the instrument. In addition to fretboard inlay, the headstock and soundhole surround are also frequently inlaid. The manufacturer's logo or a small design is often inlaid into the headstock. Rosette designs vary from simple concentric circles to delicate fretwork mimicking the historic rosette of lutes. Bindings that edge the finger and soundboards are sometimes inlaid. Some instruments have a filler strip running down the length and behind the neck, used for strength or to fill the cavity through which the truss rod was installed in the neck.