According to a guitar pickups guide, a guitar pickup is a device that is used for trapping vibrations made by guitar strings and then changing them into electronic signals that will be recorded and amplified. It is usually used with acoustic-electric and electric bass and rhythm guitars and come in passive (multi-transducer and magnetic) and active (piezoelectric and optical) types.
Types to choose from
Magnetic: Magnetic guitar pickups are made from permanent magnets that are enclosed within thin coils of copper wire, and may either be connected to a pickguard or neck (ideal for archtop acoustic-electric jazz guitars) or mounted on the body of the guitar. The voltages from magnetic string vibrations travel through radio transmissions or cables to be recorded or amplified. With outputs between 1 V rms to 100 mV rms, high-output models create more flux through strong magnets while others heighten voltage by increasing wire turns.
Piezoelectric: Piezoelectric guitar pickups are used as alternatives to magnetic ones. Besides providing unique sounds and producing great output impedance, they rarely pickup unnecessary fields like hums and feedback. They are also fitted with buffer amplifiers to avoid losing full frequency responses.
Multi-transducer: These guitar pickups produce different outputs, with each one dedicated to a particular guitar string. Allowing independent amplification and processing, they may be built into guitars and synthesizers but they are still relatively uncommon.
Optical: Optical guitar pickups function using LED light sources that give off light beams that are regularly interrupted by the strings. Using photodiode or phototransistor detectors, a guitar pickups guide will tell you that these guitar pickups are immune to magnetic and electric interferences.
Some things to remember
Semi-linear pre-amplifiers are great with piezoelectric guitar pickups because they prevent louder clippings from happening, and then makes whatever passes through less noticeable.
If you’re looking to achieve a wider range of sounds, then a piezoelectric guitar pickup will do this for you, over magnetic ones.