Now that we’ve established the difference between active and passive pickups, let’s look at different types of pickups that can fall into either the active or passive category.
Pickups consist of a magnet around which a copper wire is coiled. When the vibrations of a bass string disturb the magnetic field of the magnet, small voltage fluctuations in the copper coil are produced. These fluctuations are then transmitted to the bass amp, amplified and translated into sound.
There are two prominent pickup designs based on the number of coils used in a pickup’s construction – single-coil and double-coil.
Single-Coil Pickups
Single-coil pickups have one coil wrapped around the pickup’s magnet. Single-coil pickups are often bright and clear sounding. A drawback is they can pickup external noise and give off a humming sound. Radio waves, computer monitors, and florescent lighting can all cause this humming/buzzing. If two single-coil pickups are used (as on a Fender Jazz bass) and the pickup volumes are set equally, the noise will get cancelled out. If you just use one of the pickups, you may pickup some noise.
Double-Coil - Humbuckers
Just as two single-coil pickups can be put together to cancel hum, a double-coil pickup can be created to cancel the hum within one pickup. These pickups are often called humbuckers or humbucking pickups for their hum-reducing qualities.
Humbuckers tend to roll off some of the tonal highs when they cancel the hum and they usually have more output than single-coils.
Split-Coil Pickups
Split-coil pickups are basically double coil pickups split apart. This is what you see on Fender Precision basses. Instead of one double-coil underneath all 4 strings, the pickups are split in two — each under one pair of strings.
Piezo Pickups
Piezo pickups are less common on electric basses, but you may run into them. A piezo pickup senses the actual vibration of the string through contact with the string at the bridge contact point. These are often found in acoustic bass guitars. Since piezos don’t rely on magnets it is possible to use non-metal strings such as nylon strings. Piezos, without the right kind of pre-amp, can sound brittle and thin.
Optical Pickups
The newest kind of pickup available is the optical pickup. Optical pickups use light to sense the vibrations of the strings instead of magnets. These are still very uncommon, but may catch on.
Other Pickup Terminology:
Soapbar pickups refers to the shape of the pickup housing. They look like bars of black soap. Often found on 5- and 6-string bass guitars.
An MM-style pickup refers to pickups created by and used on MusicMan basses.
Bass Pickup Placement
Where the pickup is located along the length of the string plays an important role in the tonal characteristics of the pickup. As you get closer to the bridge, a string’s sound is thinner and brighter. As you near the neck, the tone is fuller and warmer. The tone put out by each pickup depends a lot on where the pickup is located beneath the bass strings.
Number of Pickups
Some basses, like the Fender Precision bass, have only one pickup. Many bass guitars have two pickups. With two pickups, the pickup nearest the neck is called the neck pickup and the one nearest the bridge is called the bridge pickup.
The neck pickup gives off fatter, warmer tones while the bridge pickup has a brighter, thinner sound.
You can emphasize or de-emphasize either pickup to get a wide range of tones.
Bass Pickup Summary
If you are buying your first bass, I would suggest getting a P-J pickup configuration. This means one humbucking P-bass (Precision bass) style pickup near the neck and one J-bass (Jazz bass) style pickup near the bridge. This way you get a wide variety of tones and you can get an idea of the sonic qualities of each type of pickup. If you don’t want a P-J setup, at least be sure to get something with two pickups. You want the tonal variety that will give you.
The controls on a bass are much like that of a stereo system. There are knobs for volume and tone – bass, treble and sometimes mid.
Volume Knobs
Bass guitars either have a master volume for all pickups, or two separate volume knobs – one for each pickup. With a master volume knob there is a separate knob that blends or balances the two pickups. A master volume is a little easier to control and set.
A few basses may have a pickup selector switch. A 3-way pickup selector switch has 3 settings: both pickups on, the bridge pickup on, or the neck pickup on.
Having one volume knob, two volume knobs, or a switch basically give you all the same options.
Tone Knobs
All basses have at least one tone knob. This allows you to adjust the amount of bass or treble frequencies output by the bass.
Passive basses often have just one tone knob that cuts the treble frequencies.
Active bass guitars have more tone knobs. An active bass will have at least a treble knob and a bass knob. These will allow you to both cut and boost the treble and bass frequencies.
Some basses will have a mid-range knob. This allows you to cut or boost those frequencies that fall between the bass and treble knobs’ frequencies. Some basses feature a sweepable mid-range. This allows you to choose from a spectrum of mid-range frequencies you wish to cut or boost. Otherwise the frequency is set for you as it is on the bass and treble knobs.
You may come across terms like 3-band EQ. Each frequency is a band. Three-band means bass, mid, and treble. A 2-band EQ would mean just bass and treble.
Having more knobs is convenient, but don’t forget you can do a lot with the EQ settings on the bass amp. And, the amp’s electronics generally sound better. With the knobs it’s nice to be able to adjust your tone right on your bass. Or, if you record your bass directly rather than through a bass amp, you can shape your tone a bit more.
You shouldn’t be too concerned with the strings that come with a bass you are buying. Strings are fairly cheap and are easily replaced. (Please refer to the guide to changing your bass strings.) The strings you use will have a great impact on your bass. You should experiment with a number of different types of bass strings. For more info, check out the bass strings faq.
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