As with standard electric guitars, the sound captured by the pickups is extremely important in the tone achieved for conveyance to audience or recording. There are basically two different ways in which the pickups on bass guitars use electronics to capture the sound produced by the strings. Most electric basses use magnetic pickups to capture the sound created from string vibration. The other main type of pickups is non-magnetic.
Magnetic pickups possess magnets that create a magnetic field that is interrupted and fluctuates by the vibrations created when the strings are picked or plucked. These fluctuations produce electrical current in the metal coils within the pickups, creating an electrical signal that is then sent to the bass guitar amplifier for processing and amplification in order to be converted back into an acoustic sound signal. The magnetic pickups work in basically the same way as the coil within a dynamic microphone converts sound to signal, minus the diaphragm. Pickup arrangements come in various styles, each purporting to get the most sound out of bass string vibration. The main difference between magnetic pickups found in electric basses can be observed by the number of magnetic poles (4 or 8) and the number of coils found within the pickup itself (single or double). The tried and true methods created by Leo Fender when he designed the first electric bass have been mimicked in assorted ways over the years, with most basses possessing one or two pickups, usually one nearer the bridge for a brighter sound and one nearer the neck joint for warmth. A dual coil pickup is called a humbucker and possess two rows of exposed magnetic poles while the single coil pickup possesses just one. The other type of magnetic pickup, the soapbar, gets its name by its design (it looks like a bar of soap) and does not possess visible poles.
Types of non-magnetic pickups are piezoelectric pickups and optical pickups. Piezoelectric pickups use a transducer crystal to convert string vibrations into electric signal for the amplifier. Because vibrations are captured non-magnetically, non-metal strings made of materials such as nylon or rubber may be used. These different materials when used in bass strings provide a much different tone than produced by metal strings, often mirroring the sonic qualities of a double bass, especially on fretless models. Optical pickups use an L.E.D. to track string movement optically. This arrangement allows for high volume production without the annoying white noise or interference generated by traditional magnetic pickups at high volumes.
The best way to find the right pickup arrangement for a given bassist is by playing every kind of electric bass one can get their hands on. Local music stores like Austin's Strait Music Company stock basses that are representative of all styles and brands to provide every bassist with a wide array of sounds and tones to choose from.
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