Pickups are the components in electric guitars that convert the sound coming from the strings into an electrical signal to be transmitted to an amplifier. Essentially they are made up of a wire that is wound up many times into a coil, but there are many different types with slightly different components. The wire is wound around a magnet so that when the strings vibrate, they alter the magnetic field around the magnet, which in turn generates current in the wire. The characteristic tonal quality of the pickups varies according to their components and construction, and so different ones can be used according to what style of music you want to play.
As the name suggests, these versions consist of a single wire winding and are usually found on Stratocaster type guitars. They 'pickup' sound from a very localised section of the guitar and have a bright twangy tone that is full of character. They tend to have a lower output and be more noisy than humbuckers - i.e. subject to feedback!
These versions are made up of two coils of wire and take up a larger space than single coils (see Fig.2). The magnets inside each coil are reversed in polarity and this acts to cancel out any unwanted hum or interference from other sources, hence hum 'bucker', American slang.
The extra coils give them a greater power but makes them less responsive to higher frequencies. Their increased width gives them a longer area of the string over which to receive sound. Humbucker tones are consistent and powerful with less twangy character than single coils. Because they are less noisy than single coils, they sound great with the distortion turned up!
These are large single coil versions, and were originally found in early Gibson Les Paul guitars. They have a powerful tone similar to humbuckers but retain the characteristic ‘twang’ of single coil pickups (see fig 3).
Bass pickups tend to be named after the styles of basses that they were first found on, however many modern variations exist and basses can have variations in different styles – the most common being the P and J formation. As with many differences between bass and electric guitars, basses employ the same components but tend to be a bit more chunky!
Precision Bass-style pickup (Split Coil)
Fenders Precision bass style 'pups' consist of two separate coils that are offset from one another. These are reversed in polarity to form a staggered humbucker (see fig5). These produce more midrange due to their deeper set coils and pole pieces resting in-between the strings. They are generally positioned near to the neck of the guitar.
Jazz bass-style Pickup (Single Coil)
These large single coils were first used in Fender Jazz basses. The single coil stretches the width of all of the strings, with pole pieces lying directly underneath each. These pups give a tighter treble attack great for finger playing, and are generally located at the bridge end of the guitar.
First developed in Music Man basses, this is a large profile, dual coil version with wide spread metal poles giving ultimate bass tone. Music Man, now owned by Ernie Ball, were the first production bass guitars to use active circuitry.
Having 'active' pickups means that they batteries are needed to operate the electrics. This boost in power gives more control over the frequency range transmitted, so active bases tend to have more tone controls, including bass, middle and treble boosters.
They are generally placed in the neck, middle or bridge position on a guitar in order to achieve different tonal qualities. Whereas Stratocaster type guitars have single coils in the neck, middle and bridge, Les Paul style guitars generally have dual humbuckers in the bridge and neck positions. The variations in types and position affects what sort of sounds your guitar will make when plugged in.
Their position affects the output sound of a guitar because the sound that the strings make varies from bridge to neck. To avoid getting too technical it can be said that when the string vibrates, it takes on many different shapes. By placing the pickups in different places along the string, they pick up these shapes differently and so the sound that you get changes.
As you move closer to the bridge, they get more treble and the sound gets quieter. The closer to the neck you go the tone becomes louder and warmer with more mid tones. In most Stratocasters, all three of them are of the same type – it is their location that makes them give out different sounds.
Selecting specific versions for certain sounds allows you to take these differences into account. For example it is common to find a high output bridge one (to compensate for reduced volume) with a vintage style neck version (to concentrate on the warm tones). These combinations of different types allows you to customise your sound and gives you a more versatile range of tones out of a single instrument.