The ARP Omni II is a late-1970s divide-down polyphonic ensemble synthesizer that combined lush string textures, a simple but effective polyphonic synth section, and a separate monophonic bass voice in one performance-oriented keyboard. Introduced at the end of ARP’s classic era, it mattered because it gave working players something many still wanted badly in that period: immediate orchestral scale, real stage practicality, and the ability to layer several keyboard roles at once without bringing multiple instruments.
Sound and character
In practice, the Omni II sounds less like a fully open-ended programmable polysynth and more like a tightly focused orchestral machine with a surprisingly strong personality. Its most famous voice is the string section: bright, grainy, wide, and animated by the built-in chorus phaser in a way that feels less refined than later studio-polished pads and more alive in the room. It does not imitate real strings with realism in the modern sense. What it does instead is create that unmistakable late-1970s and early-1980s synthetic ensemble glow: a moving sheet of tone that sits between organ, string section, and cinema haze.
The synth section is where the Omni II becomes more than a string machine. Its filter, envelope, LFO control, and waveform shaping let it move into brass stabs, nasal leads, hollow synth chords, harpsichord-like plucks, and animated sweeps that cut through a mix in a very period-correct way. There is a characteristic tension in its sound: the raw material is fixed and somewhat constrained, yet the filter gives it just enough sculpting power to turn preset-style sources into musically expressive parts.
The bass section, though monophonic and simpler than a dedicated monosynth, is one of the reasons the instrument has stayed memorable. It gives the Omni II real low-end purpose rather than making it just a pad machine. That matters historically because the keyboard could cover strings, chordal color, and bass support at once. Sonically, the result is not luxury or finesse. It is density, immediacy, and arrangement efficiency.
Overall, the Omni II leans unmistakably vintage: broad rather than delicate, slightly coarse rather than silky, and atmospheric without becoming abstract. Its sound is strongest when used for layered arrangements, suspended harmonies, post-punk drama, glam-art rock color, and ensemble textures that need motion without needing programming depth.
Features and architecture
- Manufacturer: ARP Instruments, Inc.
- Year: 1977
- Production years: Commonly cited as 1977–1981, though some vintage references list 1978–1981.
- Synthesis type: Analog, divide-down ensemble synthesis with subtractive control in the synth section.
- Category: Polyphonic string/ensemble synthesizer with separate poly synth and monophonic bass sections.
- Polyphony: Fully polyphonic string and synth sections via divide-down architecture; monophonic bass section.
- Original price: I am leaving the launch price out here because I did not find a period figure I could verify with enough confidence across reliable sources.
- Current market price: Usually sits in the low-to-mid four-figure used range, with serviced examples often climbing higher.
- Oscillators: Divide-down top-octave architecture; string voices include Violin and Viola, with Cello and Bass available in the lower range; synth section offers 4’ and 8’ pitch ranges plus hollow waveform switching.
- Filter: 4-pole 24 dB/oct low-pass VCF in the synth section; separate 2-pole low-pass bass filter.
- LFOs: One LFO with speed and depth control routed to the synth filter.
- Envelopes: String section has attack and release; synth section has ADSR; bass section uses a simpler AD-style contour with staccato behavior.
- Modulation system: VCF frequency and resonance controls, ADSR amount to filter, LFO amount to filter, pedal/accessory depth, and trigger behavior options.
- Sequencer / arpeggiator: None.
- Effects: Built-in chorus phaser; the synth section can also be routed through the phasing circuit.
- Memory: None.
- Keyboard: 49 keys / 4 octaves, with a split layout.
- Inputs / outputs: XLR and 1/4-inch main outputs; separate 1/4-inch outputs for strings, synth, and bass; upper gate out, lower gate out, trigger out, VCF CV in, footswitch input, and pedal input.
- MIDI / USB: None from the factory.
- Display: None.
- Dimensions / weight: Weight is documented at 39.5 lbs; I am not including dimensions because I did not verify them confidently enough.
- Power: AC mains; service documentation indicates region-specific power hardware variants.
Strengths
- It delivers full-width ensemble sound immediately. The divide-down architecture gives the Omni II the kind of instant chordal mass that players in the 1970s desperately wanted and that many limited-voice polysynths could not deliver in the same way.
- The chorus phaser is central, not decorative. This is not an effects add-on that flatters an already complete sound. It is part of the instrument’s identity, creating motion, width, and the synthetic “orchestra” quality that defines the Omni line.
- The synth section adds real musical flexibility. Even though the instrument is not deeply programmable, the filter, envelope, LFO, and waveform options push it beyond static string-machine duty into brass-like attacks, sweeping chords, and lead textures with genuine character.
- The separate bass voice makes it arrangement-friendly. The Omni II can cover multiple roles at once, which is one reason it worked so well for live players and lean band lineups.
- The rear-panel section outputs are unusually practical for its class. Being able to split strings, synth, and bass for separate amplification or processing turns a seemingly simple keyboard into a much more stage-usable instrument.
- Its limitations help define a recognizable voice. Because the Omni II cannot become anything, it remains very good at being itself: a late-70s ensemble synth with an assertive, cinematic, and unmistakably human-feeling instability.
Limitations
- It is not a true programmable polysynth in the Prophet-5 sense. The Omni II offers control, but not deep voice architecture, patch storage, or independent voice design.
- The divide-down approach favors mass over nuance. You get huge polyphony and immediate coverage, but not the kind of per-voice articulation or timbral independence that later polysynths made standard.
- There is no memory, no sequencer, no arpeggiator, and no MIDI from the factory. In a modern studio, that means either manual recall or reliance on aftermarket modification.
- The interface is immediate, but the palette is bounded. It is excellent for ensemble colors, sweeps, and certain period textures, yet it is not the kind of instrument you buy for radical synthesis exploration.
- Vintage ownership can be maintenance-heavy. Service history matters, because sliders, key action, capacitors, and power-supply health affect whether an Omni II feels inspiring or exhausting.
- Its best sounds are stylistically loaded. That is part of the charm, but it also means the Omni II tends to announce its era unless it is used very deliberately.
Historical context
The Omni II arrived in a transitional moment for keyboard design. In the mid-to-late 1970s, musicians wanted polyphony, but full-blown programmable polyphonic synthesizers were still expensive, limited in voice count, or both. ARP’s answer was not to chase that problem head-on with a luxury flagship in this product line. Instead, it extended the divide-down ensemble concept that had already proven musically useful and made it broader, more flexible, and more stage-oriented.
Seen in that light, the Omni II was both conservative and smart. Conservative, because it kept one foot in the string-machine world of preset-derived orchestral textures. Smart, because it recognized that many players did not need laboratory-style synthesis as much as they needed one keyboard that could cover strings, chordal color, bass support, and simple filtered synth parts in a live setting.
It also belongs to ARP’s visually and culturally later phase. The black-and-orange styling tied it to the company’s late-1970s design language, and the updated keyboard behavior improved articulation on non-string textures compared with the earlier Omni. The result was not a reinvention of the concept, but a refinement that made the instrument more musical in actual use.
Legacy and significance
The Omni II matters because it represents a branch of synthesizer history that is easy to underrate if one focuses only on canonical programmable polysynths. It is not important because it was the deepest instrument of its time. It is important because it solved a working musician’s problem with striking effectiveness: how to make one keyboard fill space like several.
That distinction matters historically. The story of synthesizers is not only the story of maximum control. It is also the story of practical musical coverage, of hybrid instruments that sat between organ logic, string-machine logic, and synthesizer logic. The Omni II sits exactly in that overlap. It helped normalize the idea that a keyboard could provide orchestral scale, bass reinforcement, and filtered synth expression in one chassis.
Its legacy is also cultural. The Omni II and the wider Omni family became part of the sound world of late-70s new wave, post-punk, and art-pop not because they were neutral instruments, but because they were not. Their moving strings, dramatic sweeps, and slightly unreal ensemble textures gave bands a way to sound expansive, melancholy, mechanical, and romantic all at once. In that sense, the Omni II is less a general-purpose synthesizer than a mood engine from a very particular moment in pop history.
Artists, users, and curiosities
The Omni line became strongly associated with bands that used synthetic texture not as background decoration, but as a structural part of their identity. The Cars are closely linked to the instrument’s famous sweeping ensemble-synth sound, while Joy Division and later New Order helped make the Omni aesthetic central to post-punk atmosphere rather than mere orchestral imitation. The ARP historical archive also highlights the Omni as a key keyboard sound in Prince’s Dirty Mind, which is a useful reminder that the instrument could function as glue and pulse, not just as a misty pad source.
One of the most memorable curiosities around the Omni was ARP’s use of a magazine-bound soundsheet advertisement: a flexible plastic record that readers could tear out, place on a turntable, and play in order to hear a demonstration of the instrument. That tells you something important about the moment. The Omni’s promise was ambitious enough that ARP felt people had to hear it, not just read about it.
Another revealing detail is that the Omni II’s improvements were less about adding complexity than about improving articulation and usability. That may sound modest on paper, but it reflects exactly how ensemble keyboards survived: not by becoming endlessly programmable, but by becoming more playable and more persuasive in real arrangements.
Market value
- Current market position: A respected vintage ensemble synth that appeals strongly to players chasing specific late-70s and early-80s textures rather than to buyers seeking the most prestigious ARP collectible.
- New price signal: Long discontinued.
- Used market signal: Typically found in the low-to-mid four figures; fully serviced examples can rise beyond the core range.
- Availability: It appears with some regularity on large vintage marketplaces, but clean and fully serviced examples are meaningfully less common than rough or partially restored ones.
- Buyer notes: Condition and service history matter more than cosmetic charm. Recapping, slider condition, key action, and power-supply health should be taken seriously.
- Support ecosystem: Manuals remain accessible, parts sources still exist, and specialist restorers have kept the model viable; aftermarket MIDI solutions also exist.
- Easy or hard to find: Not impossibly rare, but not a casual local find either, especially if you want one that is truly ready to work.
- Long-term position: Stable to strengthening. It remains more of a player’s instrument than a pure trophy piece, but its historical identity and distinctive sound keep its reputation healthy.
Conclusion
The ARP Omni II is not a classic because it offered unlimited synthesis. It is a classic because it condensed several musical jobs into one instrument and gave them a voice that still feels culturally loaded and sonically specific. Its strings shimmer, its sweeps speak in a recognizably late-70s accent, and its bass gives it more authority than many ensemble keyboards ever had. In the broader history of synthesizers, the Omni II stands as one of the clearest examples of how limitation, practicality, and character can add up to lasting significance.