Both acoustic and electric guitars share many parts in common. For instance, they all have a body, neck, fretboard, and headstock.
The guitar's body is of utmost importance: it provides the resonance that shapes the tone of an electric or acoustic guitar and provides the volume (or heft) of an acoustic guitar. It also may consist of:
- flattop (or just top):
- the "front" of the guitar.
- treble/upper bout:
- the (usually) smaller curved part closest to the strings.
- base/lower bout:
- the (usually) larger curved part behind the bridge.
- the inwardly curved part between the two bouts.
Factors that affect a guitar body's tonal qualities include the type of wood, the construction (whether layered or one-piece, hollow or solid-body), shape and size, and more. However, a solid-body electric guitar's shape is mostly aesthetic rather than functional.
The bridge is found somewhere between the middle and bottom of the body. Depending on the guitar, the strings may originate from the bridge or they might simply be supported by it. Most electric guitars allow the bridge to be raised or lowered, an adjustment necessary in setting up the guitar which may easily and safely be performed by any guitarist. This is typically done by adjusting screws, which are either thumbscrews which can be rotated with the fingers, or traditional screws requiring a screwdriver.
Acoustic guitars usually have a bridge and saddle arrangement. The strings originate at the bridge, usually held in by pegs. The strings then pass over a saddle, a flat piece of material held on its side. The saddle can be made of many materials, but the most common are either plastic or bone. Synthetic bone substitutes are becoming more common.
The tremolo bar, also called the "tremolo arm," "whammy bar," or "vibrato bar," is found on part of electric guitars. It was popularized on the Fender Stratocaster, and is now seen on many different models, including some hollow-body eletrics. Another popular type of tremolo bar is the Floyd Rose. Its base will be located below the bridge. Pushing down on the bar will lower the pitch of the strings, and pulling it up will raise the pitch. Rapidly pushing and releasing (or pushing and pulling for exaggerated effect) will produce a modulation in pitch, called vibrato. Vibrato is often confused with tremolo (modulation in volume), hence the misnomer tremolo bar.
The neck of a guitar extends from the body. Some guitars may have it glued on, which is a set neck, and some may have it bolted on. A few guitars are made entirely of one piece of wood, or at the least, one piece of wood comprises the neck and part of the body, up to where the bridge is located, with the sides attached. Set necks are almost universal amongst acoustic guitars. The bolt-on or screw-on neck is similarly common with electric guitars. Both acoustic and electric guitars usually have a steel truss rod going through the neck. It counteracts the pull of the strings on the neck, strenghtening it, and reducing its curvature to an appropriate amount, also allowing for further adjustments if needed. Classical guitars do not require a truss rod, because there is less tension from their strings. Adjusting the truss rod is a step in setting up the guitar, but only an experienced luthier are encouraged to perform this adjustment. There have been several examples of alternative materials for the manufacture of guitar necks, the most noteable being a carbon fibre composite, the neck being the only structural requirement for string tension.
On the front side of the neck is the fretboard, or fingerboard. On it will be a number of metal frets, usually 20 to 24. Strings are held down behind a fret to change the note a string will produce. The first fret is the one nearest the nut (see below), unless there is one immediately after the nut, which is called a "zero fret".
All strings pass through the nut at the end of the fretboard. It roughly divides the fretboard and headstock. Its function is to maintain proper string spacing and provide an endpoint for the string. On acoustic guitars, the nut and saddle are usually made of similar material. Electric guitars commonly use plastic, synthetics, and sometimes metal. As tremolo bars can cause tuning problems, guitars equipped with them usually have some manner of locking nut, where the strings are clamped down. Fender has recently introduced the roller nut, a nut incorporating a system of ball bearings similar to a locking nut, but easier on the strings.
The headstock lies at the end of the guitar's neck. The major mechanical purpose of the headstock is to support the tuning machines (tuners) which terminate the strings of the instrument. A secondary purpose is identification; many guitar makers use a distinctive headstock shape, perhaps with logo or model information, or imitate that of a more well-known brand.
Amplifier and effects
The amplifier is not part of a guitar per se, but it is nevertheless absolutely necessary in playing the electric guitar (except for very simple practicing). The amplifier often considered part of the guitar in the sense that different amplifiers will give the guitar a different sound. Many amplifiers have effects built in, especially distortion. The most common kind of distortion is called overdrive. If the amplifier has a "lead" channel, then turning up the pre-amplifier (or "pre-amp") will overdrive the amplifier's tubes or transistors, causing the amplification not to be linear, but adding a certain distortion to the sound. The higher it is, the more distortion there will be. Turning up the pre-amplifier will, by definition, increase the volume of the sound, so to compensate there is a "gain" knob, which can be turned down to reduce the volume after overdrive. Heavy amplification can result in dangerously loud sounds even on small 25-watt amplifiers, therefore, when adjusting an unfamiliar system, one should turn down the gain knob all the way, adjust the pre-amplification, and then pluck a string or chord on the guitar, while slowly and carefully turning up the gain until it is at the desired level, then plucking again to double-check. Distortion can also be provided by effects pedals, and other pedals can apply effects such as chorus, reverb, wah-wah, compression, or countless others. Sometimes these effects may be built directly into the amplifier. (Courtesy of Wikibooks)