The Omni featured preset, electronically generated Orchestral ensemble String voices including polyphonic Violin and Viola sounds as well as monophonic Bass and Cello.

The String and Synthesizer sections of the 49-note Omni utilized the Mostek MK50240 Top Octave generator IC along with divide-down circuitry; as a result, these sections were fully polyphonic, as opposed to subsequent polyphonic synthesizers such as the Sequential Circuits Prophet-5 and Yamaha CS-80 which featured dynamically allocated, limited polyphony of 5- and 8-voices respectively (although these units featured a far more comprehensive and complex synthesis architecture).

The Omni was single-oscillator in nature; normally, the String section alone was processed through the on board, patented ARP 3-voice Chorus Phaser circuit, producing the lush, moving sound the instrument is most known for.

Examples of the capabilities and sounds of the Omni can be heard in recordings such as "Good Times Roll", "Moving in Stereo" and "All Mixed Up" from the American Pop/New Wave band The Cars' eponymous debut album.

Journey's keyboardist Jonathan Cain is reported to have used an Omni on the 1981 album Escape in particular on "Don't Stop Believin'".