When Italian synthesizer maker Siel decided to build an orchestral synth in 1979, they took an unconventional approach: instead of chasing deep programmability, they engineered a machine that could convincingly voice entire sections of an orchestra through clever preset architecture and divide-down oscillator technology. The result was a 49-note polyphonic synthesizer that became so distinctive ARP bought the design outright and rebranded it as the Quartet.
The Orchestra uses analog subtractive synthesis with four tone color families—Brass, Strings, Organ, and Piano—each containing two instrument voices. You can play any single family or blend two simultaneously, giving you combinations like Trumpet with Cello or Organ with Piano. The editing palette is intentionally minimal: each section has independent Attack and Decay sliders, a shared Vibrato control (LFO), and a Brilliance slider that shapes the overall character. The Brass section gets its own Attack parameter for snappier articulation. Selected presets illuminate LEDs showing which controls are active for your current selection, making the workflow intuitive despite the limited parameter set.
The keyboard is a standard 49-key weighted action with no velocity sensitivity or aftertouch, keeping things straightforward. The unit weighs 22.5 pounds and outputs to stereo, with no external control inputs or pitch/mod wheels—this is a preset-driven instrument designed for immediate, character-driven sounds rather than deep real-time manipulation.
The Orchestra's reputation has only grown since its discontinuation in 1982. Musicians like 808 State and Massive Attack gravitated toward its lush, unmistakable string textures, which remain difficult to replicate on other synthesizers. The later Orchestra 2 (1983) added a graphic EQ, pitch bend, octave transposition, and an Animator flange effect, but the original's simplicity is precisely what gives it its charm and sonic identity. It's a synthesizer that proves you don't need hundreds of parameters to create something genuinely special.
