Anatomy of an Electric Guitar

Continuing the series of articles about guitar hardware, let's take a look at what the various parts are on a guitar. I generally play a solid-body electric guitar, so we'll concentrate on that type of guitar here, although much of what's covered here is also relevant to acoustic and semi/electro-acoustic guitars. Let's begin by taking a look at my main guitar:

For the curious amongst you, the guitar is a model that was custom-made for me by Ritchie Thompson of Tomson Guitars.

1 - Body

A solid piece of timber, which houses the pickups, controls, etc. The type of wood used for a guitar body makes a big difference to the sound. For all the sound ultimately comes from the pickups, it owes so much to the way that the strings vibrate. This is affected by the type of wood used for the body and how well it resonates. As a general rule, if an electric guitar has a poor acoustic sound, then it is unlikely to have an outstanding amplified sound - not even good quality pickups can salvage a fundamentally weak sound.

The body of my Tomson guitar is poplar - a fairly neutral-sounding timber (and, quite often, a fairly featureless wood, but Richie managed to find a very nicely figured piece for my guitar). Ash and alder are common woods for guitar bodies, as is mahogany. The latter is generally more expensive and has a richer sound, largely due to its greater density (and, therefore, weight). Since the late 1980's a wood called basswood has been in quite wide use by guitar makers. It is a good choice of tonewood for a number of reasons; its relatively lower cost compared to mahogany, a good sound (slightly reminiscent of mahogany) and its comfortable weight.

This guitar as a single piece body, but it is more usual for bodies to be made of two or three pieces of timber joined tightly together. Multi-piece bodies are not a cosmetic issue if the guitar is painted, as this hides the join, although a skilled luthier (guitar maker) can carefully match the grain of the wood so that the join is virtually invisible even on an unpainted guitar body. Another form of joinery sometimes seen is the practice of having a thinner body topped with a cap of another timber - a classic example of this is a mahogany body with a maple top.

The timber used for a guitar should be mature and well seasoned, so as to minimise the risk of warping, etc. once it has been made into an instrument.

2 - Neck and Fingerboard

Electric guitar necks are very often made of maple, with another piece of wood on top to form the fingerboard into which the frets are set. The timber used for the fingerboard is usually either rosewood (a dark timber, as used on my Tomson) or maple (a lighter wood, which imparts a slightly brighter sound than rosewood).

The profile of the neck is usually a curved 'C'-shape, although some necks have a sharper 'V'-shaped profile. This is a matter of preference, as some people prefer the feel of 'V' neck. Also, necks come in a variety of thicknesses, from big chubby necks right down to slim 'speed' necks.

The fingerboard on an electric guitar (and a steel-string acoustic) has a slightly curved profile. Take a look at the diagram below and compare how the profile of an electric guitar neck compares to the flat fingerboard found on a classical guitar:

A feature found on some higher specification guitars, and which I asked Richie to incorporate into mine, is a compound radius fingerboard. Here, the profile changes along the neck, so that the fingerboard is more like a section of a cone than a section of a cylinder. The degree of curvature lessens towards the higher frets, and enables string bending without the the strings 'choking' against the frets.

The frets set into the fingerboard help to transmit vibration from the strings into the wood of the neck, and so need to be firmly seated (and, for comfort when playing, have no sharp edges). There are several profiles of fret wire used on guitars (low/wide, tall/thin) and these can affect the way the neck feels, although this is largely a matter of personal style and preference.

Inside the neck is a long piece of metal called the truss rod. This helps to keep the neck straight - a guitar tuned to pitch has something like 40-50Kg (roughly 100lb) of tension along the strings. The truss rod can be adjusted to compensate for any bow or crown in the neck. Beware - incorrectly adjusting a truss rod can damage your guitar, so unless you're sure you know what you're doing, leave it to the experts.

3 - Headstock

The headstock holds the machine heads which anchor the strings in place and are used to tune the strings to pitch. There probably isn't a great deal to say about this other than to point out the importance of having a straight line between the tuning post for a string and the point where the string passes over the nut.

4 - Nut

The nut is the small piece of plastic (or bone, graphite or brass) with slots cut into it at the end of the neck. The depth of the slots affects how high or low the strings are above the neck (this height is called the 'action'). For tuning stability, the strings should be able to pass freely through these slots (often helped with a bit of lubrication from pencil lead or sewing machine oil) but not so loosely that it weakens the sound.

Another common type of nut, epecially on rock guitars, is the locking nut, as is used on my Tomson. This incorporates a clamping device which locks the strings into place once they are in tune. This allows heavy use of the tremelo (see below) without the strings slipping out of tune.

5 - Neck Joint

It's worth quickly mentioning the joint between the neck and the body. The most common method is the 'bolt on' neck whereby the neck is fixed to the body with four large screws. However, another common method of joining is a glued joint. The latter has the advantage that a bit extra wood can sometimes be carved away at the heel of the neck, improving access to the upper frets when playing. My Tomson (like many of Richie's guitars) has a superbly formed glued-in neck joint with excellent access to the upper frets.

6 - Bridge / Tremelo

The bridge anchors the strings on the body, and the strings should pass over the bridge tightly in order to get the best possible sound. A common feature on many electric guitars is the tremelo (or 'trem').

In common use today there are two types of tremelo unit, both performing the same basic function. The first is the traditional style as pioneered by Fender on its Stratocaster guitars, and hence often referred to as a strat trem. The bridge is held in place on the body on a pivot mechanism, and the tension of the strings is counter-balanced by a set of springs inside the body, attached to the underside of the bridge. Pushing the tremelo arm down towards the guitar body lowers the tension on the strings (and, conversely, pulling it back up raises the pitch of the strings).

The second common type of tremelo is the locking tremelo (sometimes called a 'whammy'). This type of trem operates on the same baisc principle as the strat trem, but provides far more extreme variations in pitch. The reference to 'locking' comes from the locking nut used to help prevent tuning going awry during severe whammy bar use.

It's quite hard to describe the function of the tremelo here. It may help you to have a look at (and listen to) a separate tutorial that I've written about using the tremelo in your playing.

7 - Pickups

The pickups are what ultimately provide an electic guitar with its voice. These are magnets, wrapped with many thousand turns of wire. When the guitar strings vibrate they disrupt the magnetic field of the pickups and induce an electric current.

There are many models of pickup, but they fall into two basic categories, namely single-coil and humbucker. Single coil pickups have a brighter sound but also tend to suffer from noise or hum. Humbucking pickups were developed to counteract the noise inherent in single coil pickups - they do this, but they also have a characteristically different, thicker sound. Some humbuckers incorporate wiring whereby the one coil can be switched off, thus allowing the player to select either single-coil or humbucking sounds from a single pickup.

The position of the pickup also affects the sound, which is why many guitars have more than one pickup and a switching mechanism to select which pickup(s) are used. Pickups near the bridge tend to have a more treble-rich sound in comparison to pickups near the neck, which have a more rounded sound. This variation in sound is due to the way in which the strings vibrate at the point directly above the pickups. They are anchored at the bridge and nut, and so the degree of vibration is greater further away from these points.

Volume and tone controls complete the electrics, and allow the sound of from the pickups to be controlled.

8 - Strings

Lastly, but by no means least, are the strings. Electric guitars are always strung with steel (i.e. they will influence the magnetic field over the pickups, whereas nylon or gut strings would vibrate undetected).

Strings come in varying gauges (thicknesses) which affect the sound. The most common gauges used on electric guitars are 9's (referring to the thickness of the top E string, in 1000th's of an inch). My personal preference is the fairly common configuration of 9, 11, 16, 24, 32, 42, high to low, which provides a good balance between tone and comfort. Heavier (i.e. thicker strings) give the guitar a fuller sound, but can be harder to bend. Thinner strings are more comfortable for string bending, but have too thin a tone for my taste.

Strings don't just need to be changed when they snap. To keep a guitar sounding its best, change the strings regularly and allow them to stretch properly before finally tuning up. When opne string does change, it's usually best to change all 6 strings anyway so that you aren't left with one bright-sounding new string and 5 slightly duller sounding old ones.

Finally...

That concludes our brief look at the construction of the guitar. I hope you've found it useful. In future I plan to publish some further articles covering some features, such as pickups, etc. in more detail.

Lastly I'd like to point out that a guitar does require regular maintenance to keep it at its best. If you aren't too sure what you're doing, then speak to your local guitar repairer (all good music shops usually have one) - better to be safe than sorry.

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