Magnetic pickups have been around since the early 40’s, first commercialized by the engineer Adolph Rickenbacker. Since then, a wide range of guitar pickups have been designed and developed to suit different tone styles and musical genres.
In it’s simplest form, guitar pickups are permanent magnets with a coil that pick up mechanical distortions in their magnetic field and pass them on as electric signals. This operational principle hasn’t changed until today, even if the modern pickups seem to be more sophisticated.
If you’re a serious guitarist, it pays to know the differences and subtleties between the different pickups as they colour the music you produce differently, and thus, some pickups are more suitable for the genre and playing style of your preference than others.
There are no strict rules that prevent you from using one pickup technology over the other, but it’s safe to say that a soulful sustained solo is going to sound better on a single-coil pickup such as can be found on a Fender Stratocaster, whereas a mean metal riff is going to sound more powerful coming out of an active EMG humbucker, often found on a Gibson.
Generally, we distinguish between two main types of guitar pickups: The single-coil pickup and the dual-coil pickup, otherwise called a humbucker.
The first pickup to ever hit the market was the classic single-coil pickup you have come to expect on any Fender Strat guitar.
It consists of a bobbin, which contains a series of six magnetic poles. The poles are typically made from aluminium or cobalt alloy.
The bobbin is then wrapped around by up to 10,000 turns of thin copper wire, resulting in a magnetic coil.
With a higher number of turns, i.e. a thicker coil, the coil resistance increases and this in turn produces a warmer sound. Single-coil pickups are geared towards a bright, treble-heavy sound with a lasting sustain. This makes single-coils ideal for solos and clean to mid-overdriven sound often prevalent in classic rock tunes.
Dual-Coil pickups, or as they are otherwise known, humbuckers are built by combining two single-coil bobbins and wiring the coils in opposite directions. Furthermore, humbuckers carry solid bar magnets at the coil core rather than the magnetized pole pieces that is found in single-coil setups.
Magnetic coils create a base oscillation, sometimes referred to as a “hum” which an be heard when you hook a single-coil equipped guitar up to an amp. Since humbuckers feature two coils with opposing magnetic fields, the two frequencies cancel out the “humming” which has given this pickup type the name “Humbucker”.
Typically, humbuckers have 2 coils with 5000 turns on each. Both coils have a lower resistance that the single-coil setup and thus have a flatter and warmer, more midrange-heavy sound.
Humbuckers also come in the form of active pickups. Active pickups are equipped with a 9V battery and their own circuitry to boost the weak input signal of the guitar. Active pickups have a very aggressive attack, i.e. they go from quiet (idle) to loud and heavy (engaged) in a heartbeat. These characteristics have made humbuckers the go to choice for hard rock and heavy metal tunes, where bassy and gnarly riffs are involved and the gain knob is turned to 11.
You are now familiar with the two most popular types of pickups, but there is also a third option that is widely used by guitarists: Piezo pickups.
This type of pickup uses piezoelectric crystals instead of magnets to generate a signal.
There are some benefits that come with the use of Piezos. Firstly, since they do not require an electromagnetic field to function there is no need for metallic strings. Piezo pickups are perfectly capable of picking up vibrations created by nylon strings such as used on classic and acoustic guitars.
Furthemore, piezo pickups do not suffer from electromagnetic feedback or interference. If you have ever played on an electric hollow body guitar, you would know how painful it is to play with traditional pickups that generate a lot of interference. Here the piezos really shine, as they do not have this problem.
Piezo pickups come in a range of shapes and forms, but traditionally they have a disk form which can be directly attached to a guitar, beneath the bridge section. Piezos are very small and can be mended to fit the space and form that is ideal for the application they are intended for.
Piezos are most commonly found on acoustic guitars and are known for a mellow and true town, without colouring the input in a traditional direction.