Introduction to the Electric Guitar

Of course we have all seen and heard the electric guitar in action hundreds of times. Since the 1950s this instrument has been associated with some of the most iconic figures of the music world. Without question the electric guitar has played a pivotal role in the development of today's popular music. But many people know little about how the instrument actually works. How is a sound that can be heard by thousands of people at a live gig produced as a result of a guitarist hitting some metal strings which are less than a millimetre in thickness? Obviously this is not something that the majority of people will ever need to know, but for those of us who want to play the instrument it is necessary to have a small amount of (not very) technical knowledge.

You may find that you have to return to the latter part of this lesson as our course progresses to remind yourself what certain parts of the instrument do. However, we begin by considering what the electric guitar will actually be doing whilst we play our music – how it changes the notes we play into the sounds that we hear from the amplifier.

How does the electric guitar work?

What makes an electric guitar different to an acoustic guitar is what happens in the body of the instrument (indicated in Figure 1 below). As with an acoustic guitar, vibrations of the instrument's strings produces musical notes that we can hear. Each string is by convention set up to produce a different pitch when it is plucked, but by pressing a string down in different places on to the fretboard, each string can produce notes of several different pitches. An electric guitar differs from an acoustic guitar insofar as it converts the notes that are being produced into an electrical signal which can then be routed through an amplifier and speaker.

But how are these notes converted into an electrical signal? The answer to this question lies with the slightly raised bits of metal located in the centre of the instrument's body - the pickups. These are magnets wound with coils of wire, which change the vibrations within their magnetic field caused by the guitar strings into electrical energy (in the form of a vibrating current within the coil). This signal then passes through a simple electrical circuit, being modified by tone and volume controls on the body of the guitar, before passing down the lead into an amplifier or other device which converts this electrical signal into something that we can hear.

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