EML Poly-Box

When monophonic synthesizers ruled the 1970s, the Poly-Box arrived as an ingenious workaround to a fundamental limitation—a pitch-following chord generator that could extract polyphony from any single-voice synth by tracking its oscillator output and generating harmonies in real time.

The Poly-Box operates through two banks of 13 pitch sources each, creating 26 simultaneous pitch outputs that respond to incoming audio signals with remarkable accuracy, even tracking vibrato and portamento without losing lock. A small 13-key keyboard lets you play chords manually or engage the built-in chord memory to automatically transpose preset voicings along with your melody. The unit features 26 patches of memory to store your favorite chord configurations, making it easy to recall setups across different sessions. Audio passes through a single 1/4-inch input and output, while CV and Gate connections allow integration with modular systems. The pitch sources span from one octave above to three octaves below the source oscillator, giving you substantial harmonic range.

The Poly-Box has become something of a cult object among vintage synth enthusiasts and modular players who appreciate its elegant solution to a problem that would later be solved through true polyphonic instruments. Its rarity and unique approach to harmony generation have kept it relevant decades after its 1977 debut, with users consistently praising how naturally it tracks pitch and how musically useful the chord memory proves in live performance and studio work.