The signal from an electric guitar is generated by the vibration of the metal strings over the magnetic pickups. How these pickups are wired can have a dramatic effect on the tone of the guitar when played through an amplifier. The difference between series and parallel wiring offers perhaps the most dramatic tonal variation.
When two pickups are wired together so that the signal passes through one to pass through the other, they are wired in series. Pickups wired in a series don't draw a load from each other, resulting in a stronger overall output signal. The twin sets of coils in a humbucker-type pickup seen on Gibson Les Paul guitars are wired in series, even though the two separate humbuckers are wired in parallel. Series wiring delivers the kind of powerful sound with long sustain that is familiar to Les Paul players.
In a parallel connection the pickups are wired in such a way that they share common connections in the guitar circuit. This has the effect of splitting the signal, with the result that the output is noticeably lower. This is exemplified by the Fender Stratocaster where the bridge and middle position, and the middle and neck position, arranges the pickups in a parallel circuit. The sound produced by these combinations is thinner and has more treble, with far less sustain than on a Les Paul.
Fender Stratocaster players often modify the wiring to enable them to play the bridge and middle, and also the middle and neck pickups in series rather than in parallel. This adds flexibility by enabling the instrument to produce a fuller sound than is typical of the Stratocaster. Conversely, Les Paul players often enable parallel wiring within each humbucker pickup, as well as series wiring of the bridge and neck pickups together. In both cases a push/pull type of switch enables the player to quickly flick between each arrangement.
What is Best?
For many players, the choice of series or parallel wiring is one that will be dictated by the type of guitar they purchase, and the type of music they play. The thinner sound of a single-coil Fender Stratocaster is arguably more versatile than a Les Paul, but it can be easily modified to be more flexible by hooking up its pickups in a series circuit. Equally, the full-bodied sound of a fully amplified Les Paul can be toned down by parallel wiring the coils in the pickups. Whatever your personal preference or style of music, neither circuit is better than the other, but rather the choice must be one that is best for each individual player.
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