facilitate rockabilly or bluegrass "slap" playing, while the thumb of the right hand rests against the side of the fingerboard. The strings are usually plucked over the fingerboard near the end. The left hand is used to stop the strings by pressing down with the fleshy part of the finger, generally using the ball of the thumb at the back of the neck to obtain pressure. In the highest positions on the fingerboard, where the neck on an EUB gets considerably thicker, the left hand usage can be modified with the whole hand being brought round to the front of the instrument and the thumb taking the place of the index finger. These positions are called the 'thumb positions' in double bass parlance. In these positions, it is necessary to rest the neck of the bass against the player's left shoulder in order to support the neck against the pressure of fingers on the strings. On the shorter scale EUBs, bass guitar fingering can be used over a large portion of the fingerboard and thumb positions may not be necessary. On the longer scale models, due to the larger distances between notes, the double bass (Simandl) fingering method usually has to be used. Comparison with the double bass 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). If the EUB's bridge and fingerboard are relatively flat, like those on an electric bass, then it is not possible to use the bow on the inner strings. By using suitable (gut or synthetic core) strings and adjusting the amplifier tone and distortion controls, an EUB can emulate an acoustic double bass. By using brighter (steel core) strings, tone controls and bass effects, an EUB can also take on a sound similar to a fretless bass guitar. Since the EUB transmits its sounds through a pickup, the tone is brighter than that of the acoustic double bass, which transmits its tone via the sound post to the back of the body. Compared to a double bass, the tone produced by an EUB is much less modified by its wooden 'body'. Genres and performers The Ampeg 'baby bass' has been popular in Cuban