Guitar Pickup Basics

A guitar pickup essentially consists of a coil of wire wrapped around a magnet (or series of magnets, as would be the case). When a steel or nickel string vibrates, it interrupts a magnetic field, creating energy. This can be explained by Faraday's Law of Induction.

Faraday's Law of Induction: The induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit.

In other words, when a magnetic field is disrupted, it creates energy in a closed circuit that is also in its field.

Magnets: Lower strength magnets give the guitar a warmer, bassier tone and sound better clean, while higher strength ceramic magnets have more treble and bite, and are usually desirable for use with distortion.

Coils: The more wraps in a pickup's coil, the more output it has. The kind/age/preparation of the wire also alters the tone. Most coils are sealed in wax to prevent feedback.

Single Coil Pickups: The first form of guitar pickup. While picking up the sound of the guitar, early single coils would also pick up stray radio frequencies, which would result in an annoying humming sound. Single coils are still used, however, because of the quality of their clear, bright sound, and because many improvements have been made that minimize the hum.

Humbucking Pickups: This pickup literally "bucks" the "hum" from the signal, and was first invented as a solution to the single coil. The humbucker is essentially comprised of two single coils next to each other that share a large magnet at the base. Each coil has oppositely wound wiring, which effectively cancels out the hum caused by stray radio frequencies. The unintentional effect that came with the humbucker was a higher output due to the multiple, stronger magnets.

Piezo Pickup: A pickup that functions based on the principle of piezoelectricity. A ceramic disc (or more recently, a synthetic polymer) is affixed to a vibrating surface (usually the bridge of a guitar or other stringed instrument). The vibrations create energy which is sent to the amplifier.

Piezoelectricity: The charge which accumulates in certain solid materials (in this case, ceramics) in response to applied mechanical strain. This is essentially electricity resulting from pressure.