What is a pickup and how does it work?
At its most basic, a pickup is anything that captures sound vibrations and turns them into a signal which can then be amplified or recorded. Pickups are best suited for instruments that produce vibrations. A pickup is a transducer, meaning it converts one type of energy to another.
Broadly speaking, there are two types of pickups: magnetic and piezoelectric. Magnetic pickups capture sound vibrations through a magnetic field that pulses in time with the vibrations around it. Piezoelectricity works by conducting vibrations directly from the instrument to the pickup, which is made of materials that are particularly sensitive to this force. For guitars, the most common locations for piezo pickups are under the saddle or on the sound board or bridge plate. (Read more about the difference between undersaddle and bridge plate pickups.)
Magnetic pickups are most popular in electric guitars. This makes sense if you've ever played or held an electric guitar: They are very solid and do not produce a lot of vibrations, other than in the strings themselves. Acoustic guitars, on the other hand, have a hollow body and you can feel the sound vibrations resonate throughout the whole instrument.
Pickups are generally preferred over microphones in performance settings. A microphone doesn't care where sound is coming from: It’ll amplify the sound of your guitar just as easily as the drums behind you or the bass next to you. A pickup doesn’t “hear” — it’s attached to your instrument and can only “feel” what you’re playing. Microphones, however, are very popular in recording settings when all outside noise can be eliminated.
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