How does a bass pickup work? What is the difference between the various kinds of pickups?
toc A bass pickup works by detecting the changes made by the moving string in the magnetic field of the pickup. A normal bass pickup consists of one or more magnets wrapped in coils of thin wire. The vibration of the metal strings changes the magnetic field of the pickup, and the changing magnetic field produces a voltage across the two ends of the wire wrap. This voltage can be detected and amplified by a bass amp, and then converted back to sound by a speaker. This signal needs to be amplified in order to be audible. Passive pickups do not amplify the signal at all: they require the bass amp to do all of the amplification. Active pickups contain a small amplifier inside the pickup housing. This amp boosts the pickups signal to a higher level which is then sent down the instrument cable into the amplifier. (Good amplifiers have two input jacks, one for active basses and one for passive basses, to reflect this difference.) You can also get basses which have onboard preamps which take t
