Certainly, if presented with an acoustic guitar and an electric guitar, most people can identify which is which. After all, while the acoustic instrument has a large hole in the middle, the body of the electric instrument is smooth and apparently solid. (Some electric guitars are solid core, some are hollow and some are a combination of both, but that is beside the point in this instance). At any rate, acoustic and electric are easy to tell apart on sight. And of course, the sound of the electric guitar and the manner in which it is produced is equally characteristic. Yet what are all the little parts and pieces that allow that this instrument to do what it does? There are quite a few, and one of the most essential is the pickup.



A pickup is a transducer, or a device that converts one type of energy into another. On an electric guitar, pickups are used to detect string vibrations and convert those vibrations electrical energy. This results in an electrical signal, which can then be electronically amplified. Most pickups for electric guitars are electromagnetic in design. They contain magnets that are tightly wrapped in a coil, or coils, of copper wire. Such pickups are usually located right underneath the guitar strings. The vibration of the strings causes a small voltage to be created in the coils surrounding the magnets; this signal voltage is later amplified.

Traditional electromagnetic pickups are either single-coil or double-coil. Single coil pickups are susceptible to noise induced from exterior electric fields. Fortunately, in the mid-1950s, the introduction of the humbucker put an end to this problem. This pickup has two magnets wrapped in copper wire. The magnets are of reversed polarity and the wire is wound in opposite directions, and the result is that they are all but unaffected by interfering electric fields.

Piezoelectric, or piezo, pickups represent another category of pickup. These employ piezoelectricity, which is the ability of some materials (such as crystals, ceramics and bone) to generate electric potential in response to applied mechanical stress. Piezos are popular in hybrid electro-acoustic guitars. A crystal is located under each string, usually in the saddle. When the string vibrates, the shape of the crystal is distorted, and the stresses associated with this change produce tiny voltages across the crystal that can be amplified and manipulated.

Some guitarists use hexaphonic pickups, which can be used in conjunction with piezo pickups. In a hexaphonic pickup setup, each guitar string has a separate piezo that obtains a separate output. These outputs, of which there are six, are then fed into the hexaphonic pickup. Such an arrangement allows the final signal to be easily modified. With modern on-board modeling technology, an electric guitar's signal can be manipulated to attain a variety of different sounds, and a hexaphonic pickup makes this easier.

The type and model of pickup or pickups used can greatly affect the tone of the guitar. Typically, humbuckers are associated with a heavier sound, while single coil pickups are used by to create a brighter, twangier sound with greater dynamic range. And as mentioned, hexaphonic pickups are useful in enabling the guitarists to produce a variety of sounds.