Acoustic Guitar Parts

See Wikipedia, Guitar, This illustration reprinted from  http://en.wikipedia.org/wiki/Guitar (On Dec. 12, 2008).

Names of   Acoustic Guitar Parts     1. Headstock    2. Nut    3. Machine heads (pegheads, tuning keys, tuning machines, tuners)    4. Frets    7. Neck    8. Heel        9. Body   12. Bridge   14. Back   15. Soundboard (top)   16. Body sides (ribs)   17. Sound hole,  (with Rosette inlay)   18. Strings   19. Saddle   20. Fretboard (or Fingerboard)

Acoustic Guitar Headstock

The headstock 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 their pitch. The traditional tuning layout is 3+3 so that each side of the headstock has three tuners. In this layout, the headstocks are commonly symmetrical.

Acoustic Guitar Nut

The nut is a small strip of bone, plastic, brass, corian, graphite, stainless steel, or other medium-hard material, at the joint where the headstock meets the fretboard. Its grooves guide the strings onto the fretboard, 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.

Acoustic Guitar Fretboard (Also called the fingerboard)

The fretboard is a long thin 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 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 or composite materials such as HPL or resin.

Acoustic Guitar Truss Rod (see electrical guitars)

Classical guitars do not require truss rods as their nylon strings exert a lower tensile force with lesser potential to cause structural problems.

Acoustic Guitar Frets

The frets 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. 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. Frets are laid out to a mathematical ratio that results in equal tempered division of the octave.  The twelfth fret divides the scale length in two exact halves and the 24th fret position divides the scale length in half yet again. Every twelve frets represents one octave. On steel-string guitars, frets are eventually bound to wear down; when this happens, frets can be replaced or, to a certain extent, leveled, polished, recrowned, or reshaped as required.

Acoustic Guitar Neck

A guitar's frets, fretboard, tuners, headstock, and truss rod, are all attached to a long wooden extension, which collectively constitute the guitars 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. 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.

Acoustic Guitar Neck joint or 'Heel'

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 (otherwise known as set) necks, while electric guitars are constructed using both types.

Commonly used set neck joints include mortise and tenon joints, dovetail joints 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.

Acoustic Guitar Strings

Modern guitars using "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.

Acoustic Guitar Top or Soundboard 

In acoustic guitars, string vibration is transmitted through the bridge and saddle to the body via a sound board. The guitar top, or soundboard, is a finely crafted and engineered element made of tonewoods such as spruce and red 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. 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 luthiers 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.  Sound is further shaped by the characteristics of the guitar body's resonant cavity.

Acoustic Guitar Body

In an acoustic instrument, the body of the guitar is a major determinant of the overall sound quality. 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 luthiers. 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 the body is vibrated by the strings, and the response of the air cavity at different frequencies is characterised, 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 or jumbo body size amongst acoustic performers is related to the greater sound volume produced.

Acoustic Guitar Bridge

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 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 fretboard (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" – 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.

Acoustic Guitar Inlays