Keyboard bass (sometimes referred as a synth bass) is the use of a low-pitched keyboard or pedal keyboard to substitute for the bass guitar or double bass in music.
The earliest keyboard bass instrument was the 1960 Fender Rhodes piano bass, pictured to the right. The piano bass was essentially an electric piano containing the same pitch range as the electric bass (or the double bass), which could be used to perform bass lines. It could be placed on top of a piano or organ, or mounted on a stand. Keyboard players such as The Doors' Ray Manzarek placed his Fender Rhodes piano bass on top of his Vox Continental or Gibson G-101 organ to play bass lines. About the same time, Hohner of Germany introduced a purely electronic bass keyboard, the Basset, which had a 2-octave keyboard and rudimentary controls allowing a choice of tuba or string bass sounds. The Basset was in due course replaced by the Bass 2 and, in the mid-1970s, the Bass 3. All three were transistorized; the Basset was among the earliest solid-state electronic instruments. Similar instruments were produced in Japan under the "Raven" and "Rheem Kee Bass" (sic) names.
In the 1970s, a variant form of keyboard bass, bass pedals, became popular. Bass pedals are pedal keyboards operated by musicians using their feet. The guitar players or bass players of bands such as Genesis' Mike Rutherford, Yes' Chris Squire, John Paul Jones of Led Zeppelin during acoustic sets, Rush (bassist Geddy Lee), The Police (bassist Sting), Marillion (Pete Trewavas) or Atomic Rooster (organist Vincent Crane) use the bass pedals to play bass lines. Stevie Wonder pioneered the use of synthesizer keyboard bass, notably on "Boogie on Reggae Woman". During these decades the keyboard bass in its original form was still in use by some bands such as the B-52's, who used a Korg SB-100 "Synth-Bass".