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ARP Omni-2 Orchestral Ensemble Syntesizer

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The Omni featured preset, electronically generated Orchestral ensemble String voices including polyphonic Violin and Viola sounds as well as monophonic Bass and Cello. The instrument also included a monophonic Bass Synthesizer section and a polyphonic Synthesizer section. The Synthesizer section featured a 24 dB/oct Voltage-Controlled Low Pass Filter (LPF); an ADSR envelope generator and a single waveform (triangle) Low Frequency Oscillator (LFO) were both routed to control the VCF Cutoff frequency. A Waveform Enhancement switch allowed selection of a square wave voice waveform vs. the default quasi-sawtooth waveform. The ARP Omni had a unique logo that was painted on to the back face of the unit.

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 three sections of the Omni - Strings, Synthesizer, and Bass - were all simultaneously available and mixable; the String and Synthesizer sections featured separate audio outputs on the rear panel of the unit which allowed separate amplification and signal processing of these sections for stereo effects. 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. However, the Synthesizer section was processed through this circuit when a front panel "Chorus Phaser" switch was activated, simultaneously summing the String and Synthesizer section outputs and slowing the Chorus speed.

Technical Specifications
Type: Analog
Synthesis: Divide Down, Subtractive
Oscillators: 2
Waveforms: Square
Osc Modulation: Keyboard, LFO
Envelopes: 2
Evelope Paramerters: Attack, Decay, Sustain, Release
Envelope Notes::
AR: Strings
ADSR: Polysynth & Bass
Filters: 1
Types: 24dB Slope (4-pole), Low Pass
Filter Modulation: LFO
LFO: 1
LFO Parameters: Triangle
Polyphony & Tuning
Polyphony: 3
Timbrality: 1
Tuning: Standard
Modes: Mono, Polyphonic
Patches RAM: 1
Storage: Internal
Editing: CV
3-Voice Chorus Phaser
Case: Keyboard
Case Details: 61
Keyboard: 49 keys, Non-weighted, Plastic
Controls: Faders
Display Type: LED
Audio Output Connections: 1/4" Phone Jack, XLR, Mono Out
Audio Output Count: 5
Audio Output Notes: Separate outs for strings, synth, bass
CV Ports: CV IN, Gate In, Gate Out, Trigger Out
Control Features: Separate gates for upper and lower sections, VCF CV input
Year Released: 1977
Year Discontinued: 1981
Used By
Roy Ayers, Boston, Darius Brubeck, Cars, Commodores, Adrian Cook of the Electrotunes, Floyd Cramer, Rick Greenwood of Foreigner, Rick Davies of Supertramp - owned two, Earth Wind and Fire, ELO, Joy Division - Closer, Kansas, Al Kooper, Yusef Lateef, Manfred Mann's Earth Band, Mushroom of Massive Attack, Santana, Bob Seger and the Silver Bullet Band, Cat Stevens, Tangerine Dream, Pete Townshend, War, Sparks, Stevie Wonder, Allan Zavod who played with John-Luc Ponty
Design Notes:

The Omni was very popular in its time, as it was amongst the first available polyphonic electronic keyboard synthesizers. 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. Cars' keyboardist Greg Hawkes stated in a 1979 Keyboard magazine interview that all keyboard sounds heard on "Moving In Stereo" were produced by the ARP Omni. An example of the Waveform Enhancement mode can be heard as the lead line in the 1982 hit "I Melt With You" by the English band Modern English from their album After The Snow.

ARP Instruments introduced an updated version of the Omni as the Omni-2 in 1978. The Omni-2 utilized an all-steel chassis with ARP's orange and black color scheme and an updated Chorus Phaser circuit which ARP claimed to be superior to that of the original Omni. Additionally, the Omni-2's Bass voice utilized a single oscillator waveform circuit coupled with a preset 2-pole, Low Pass Filter and preset Attack Decay Release (ADR) envelope generator. A Staccato switch controlled the Bass section's envelope contour Decay time vs. the original Omni Bass voice ADSR assignment via its Synthesizer section. Further, the Omni-2 Bass section had its own audio output on the rear panel in addition to the Strings and Synthesizer outputs; separate amplification of these three distinct outputs was referred to in ARP literature at the time as "Tri-phonic". The Omni-2 also featured selectable Single- or Multiple-Trigger keyboard control of envelope contours and re-branded the original Waveform Enhancement panel control switch as "Hollow Waveform".
Manuals & Documents
MSRP List Price: $2,450 - convert
Retail Street Price: $2,300 - convert
Used Price: $500 - $700 - convert

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