ARP Instruments, having developed the large and powerful ARP 2500 for studio work, released the Soloist as a light, portable, easy-to-use performance instrument that could be placed on top of an electric piano or Hammond organ. In contrast to the flexible modular design of the 2500, the Soloist had no patch panels or cables. A set of toggle switches allowed the performer to quickly choose one of 18 preset monophonic patches that were not modifiable (note that "Voice" was ARP parlance for Preset, or Patch). This lack of programmability was compensated by giving the performer control over the voice expression, adding "growl", "wow", "brilliance", portamento, pitch bend, and/or vibrato to the timbre. A pressure-sensitive keyboard allowed players to use aftertouch to control all of these effects.