Until recently, polyphonic synthesizers were confined to the private stock of inventors, engineers and a few wellknown players who function as advisors to the electronic keyboard industry. This year the common man's version has been offered up for public consumption; one such manifestation of electronic wizardry is the ARP Omni.

Basically the Omni is a string synthesizer (bass, cello, viola and violin) which also has the capacity to produce very authentic brass, electric piano, bass and harpsichord in various combinations. The four octave keyboard is split at one and one-half octaves from the low end and will play monophonically on the low end when programmed for synthesizer bass, string bass, or cello. This helps keep the sound cleaner because an excess of bass frequencies tends to muddy the sound. The viola and violin settings are voiced so that the viola is mellower (has fewer high harmonics) than the violin. When played together, each voice is distinct, which gives the string section a very lush, rich-sounding total effect. The string sound of the Omni is even better than the old ARP string ensemble, which already far surpassed other string synthesizers on the market.

On the left hand side of the control panel eight slide controls allow the player to adjust the envelope (ADSR), the VCF (voltage-controlled filter) frequency and VCF resonance, and the LFO (low-frequency oscillator). All this amounts to control of the behavior of a note in time (how fast it swells, how long it endures); the harmonic content of a note (how bright or how mute the sound); and the depth and speed of tremelo (for phase-like effects or string vibrato).

There are two synthesizer bass footages (16' and 8') and two synthesizer footages (8' and 4') which are voiced with slightly different harmonic content to provide subtle contrasts in tone. Again, a very full-bodied effect. Although there is only one basic waveform change (sawtooth to pulse wave), the filter, ADSR and mix controls make a wide range of sounds possible.

While your hands are busy with all that, there are a couple of particularly nice features brought into play by using your feet; the sustain foot switch, which works exactly like a sustain pedal on a piano; and the foot pedal, which opens and closes the VCF, thereby creating wah-wah effects by raising and lowering the harmonic content (number of overtones) of the notes being played. The sustain foot switch is a vast improvement over older models which had less flexibility; and the foot pedal is very helpful, especially for bass patterns a la Hancock. Very funky.

Overall, the panel layout is simple and sensible; the controls most often adjusted are close to the left hand; status lights indicate which functions are in use; the unit is lightweight, and the top is wide enough to accomodate other keyboards easily. Stereo outputs facilitate splitting strings and brass into separate channels of a stereo amp and there's a Gannon XLR jack on the rear panel for balanced-line hookups. Altogether a very solid piece of equipment.

The sacrifice one makes for all the aforementioned keen, nifty features is a heavy one. Many of the advances common to most monophonic units, such as pitch bending and portamento, noise sources, and a variety of waveforms to choose from are not available here. There are no fixed rules as to what a synthesizer will do, so don't expect the Omni to duplicate every synthesized sound you've heard so far. It won't do that much, even though it is polyphonic and it has an astonishingly real string, brass and piano sound. If you prefer the broader possibilities of a monophonic unit, simply patch into the system interface jacks on the rear panel and live happily ever after.