Anatomy of the guitar
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 makes it easier to play the instrument while seated. Acoustic guitars typically have a large, round hole (the sound hole) on their faces, which, due to the resonance of the body, amplifies the sound greatly. This is why acoustic guitars are louder and project their sound further than unplugged electric guitars.
Other aspects of the guitar body consist of: -flattop: the "front" of the guitar. -treble/upper bout: the (usually) smaller curved part closest to the strings. -bass/lower bout: the (usually) larger curved part behind the bridge. -waist: 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 end of the body. Depending on the guitar, the strings may originate from the bridge or they might simply be supported by it. Most guitars allow the bridge to be raised or lowered, an adjustment necessary in setting up the guitar that 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.
One specialized type of bridge is the "Tune-O-Matic" Bridge.
The tremolo bar, also called the "tremolo arm," "whammy bar," or "vibrato bar," is only found on some electric guitars, most notably the Fender Stratocaster. 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 (the rapid repetition of one note), hence the misnomer tremolo bar.
The pickup is only found on electric guitars — in fact, the presence of one is the definition of an electric guitar. The pickup "picks up" the vibration of the strings, and sends it out to the amplification cable, which will carry it to the amplifier. A guitar usually has anywhere between one and four pickups. Two and three are common, especially since the Gibson Les Paul and Fender Telecaster use two, and the Fender Stratocaster uses three. Pickups also come in three varieties: single-coil, humbucker, and piezoelectric. All of them will sound different. Pickups can also be wired in different ways for customized sounds, but this option is best left to advanced guitarists. Pickups will also sound different depending on their positioning on the body: pickups towards the bridge will have a brighter tone and will express harmonics more clearly. Pickups toward the neck tend to sound darker and dampen harmonics.
Single-coil pickups will pick up "noise" from other electric devices, commonly heard as a faint droning 50 or 60 Hz tone. Humbuckers reduce this noise while reinforcing the musical signal, but this makes a darker tone. Piezoelectric pickups are rarely found except acoustic/electric hybrid guitars. Because they are not magnetic, they will not pick up electromagnetic noise. Humbuckers are usually preferred for heavy rock and metal, while single-coil pickups are usually preferred for country and folk music, and piezoelectric pickups might be preferred for acoustic guitars, and likely the only option for acoustic classical guitars.
Switches and knobs
Switches and knobs on the body control the pickups, and are therefore found only on electric guitars. Many guitars have just two knobs: one for volume and one for tone. Some guitars, such as the Les Paul, will have four: a volume knob and tone control for each pickup. Most guitars with more than one pickup will have a switch. For example, the three-way switch, found on many two-pickup guitars, selects between either of the two pickups, or both at the same time. Switch positions can "split" humbuckers on some guitars, turning it into a single coil and combining it with another pickup.
The neck of a guitar might extend directly from the body. This is almost universal in acoustic guitars. More commonly in electric guitars, the neck is bolted on. Both acoustic and electric guitars usually have a steel truss rod going through the neck. Classical guitars do not require a truss rod. Adjusting the truss rod is a step in setting up the guitar, but only an experienced luthier should perform this adjustment.
On the front face of the neck is the fretboard, or fingerboard. Most commonly, there are twenty to twenty-two frets on the fretboard. To play a desired note, a string is pressed against the appropriate fret. The first fret is the first one down from the nut, unless there is one immediately after the nut, which is called the "zero fret".
All strings pass through the nut at the top of the fretboard. It roughly divides the fretboard and headstock, and works as an "open-string" fret. Confusingly, the nut is also sometimes called a bridge; following this terminology, a guitar has two bridges.
The headstock is at the end of the neck and holds the tuning pegs. There is one tuning peg per string. A knob extends from each peg, which may be rotated in order to change the pitch of the string.
Amplifier and effects
The amplifier is not part of a guitar per se, but it is nevertheless necessary in playing the electric guitar (except for simple practicing). 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 cause overdrive. 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. Sometimes these effects may be built directly into the amplifier.
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