bass players, whose use of the technique was often highly syncopated and virtuosic, sometimes interpolate two, or even three more slaps in between notes of their bass line. Variants 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). The stick bass is also widely used in salsa, because its volume and tone are especially suited to that style of music, even in studio recording. 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 silent 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