fender jazz bass

In jazz, the double bass is usually played with amplification and it is most played with the fingers, pizzicato style, except during some solos, where players may use the bow. The pizzicato style varies between different players and genres. Some players perform with the sides of one, two, or three fingers, especially for walking basslines and slow tempo ballads, because this is purported to create a stronger and more solid tone. Some players use the more nimble tips of the fingers to play fast-moving solo passages or to pluck lightly for quiet tunes. The use of amplification allows the player to have more control over the tone of the instrument, because amplifiers have equalization controls which allow the bassist to accentuate certain frequencies (often the bass frequencies) while de-accentuating some frequencies (often the high frequencies, so that there is less finger noise).

An unamplified acoustic bass' tone is limited by the frequency responsiveness of the instrument's hollow body, which means that the very low pitches may not be as loud as the higher pitches. With an amplifier and equalization devices, a bass player can boost the low frequencies, which evens out the frequency response. As well, the use of an amplifier can increase the sustain of the instrument, which is particularly useful for accompaniment during ballads and for melodic solos with held notes.Like other acoustic instruments used with amplification, such as the jazz violin, a double bass is often plugged into a preamplifier, impedance-matching device, and/or a Direct Injection (DI box) box before it is routed to the PA system, electronic effects, or the bass instrument amplifier.

An example of pizzicato jazz bass technique.

In traditional jazz and swing it is sometimes played in the slap style. This is a vigorous version of pizzicato where the strings are "slapped" against the fingerboard between the main notes of the bass line, producing a snare drum-like percussive sound. The main notes are either played normally or by pulling the string away from the fingerboard and releasing it so that it bounces off the fingerboard, producing a distinctive percussive attack in addition to the expected pitch. Notable slap style bass players, whose use of the technique was often highly syncopated and virtuosic, sometimes interpolated two, three, four, or more slaps in between notes of the bass line.

In both jazz and jazz fusion bands, some jazz bassists use a modified type of double bass called the electric upright bass (abbreviated EUB and sometimes also called stick bass). It is an electronically amplified version of the double bass that has a minimal or 'skeleton' body, which greatly reduces the size and weight of the instrument. The EUB retains enough of the features of the double bass so that double bass players are comfortable performing on it. While the EUB retains some of the tonal characteristics of the double bass, its electrically-amplified nature also gives it its own unique sound. As well, an EUB is considerably easier to transport than its acoustic equivalent. The scale length of EUBs varies: some scales are 42", similar to most double basses, whilst other models have scale lengths of only 30" like a short scale bass guitar. The shorter scale can make it easier for bass guitarists to convert to the EUB.

Solid bodied EUBs produce very little sound without electronic amplification. Hollow-bodied EUBs produce a quiet tone that is loud enough for individual practice. However, since hollow-bodied EUBs do not have a large resonant cavity like a double bass, they cannot reproduce the lowest notes of the instrument without an amplifier. To amplify the EUB, the string vibrations are sensed with a pickup. Early EUBs used magnetic pickups similar to those in electric guitars, or percussive magnetic diaghram pickups (e.g., the Ampeg Baby Bass). Many modern EUBs use piezoelectric pickups located in the bridge or a combination of pickup types. The signal from the pickup is usually preamplified and equalized with a preamplifier and then sent to a bass amplifier or a PA system. For practice in a hotel room or apartment, an EUB can also be connected to headphones.

Preamplifiers and equalizers for acoustic instruments or double basses can also be used to "roll off" the treble frequencies or "notch out" the "scratchy-sounding" frequencies. Since the EUB typically does not have a hollow sound chamber, or only includes a small sound chamber, the EUB is less prone to feedback than the double bass when amplified. To use a bow with an EUB, both the bridge and fingerboard need to be radiussed (given a curve).