The Polyphone (860004), an analogue polyphonic synthesizer, was built by Le Caine's National Research Council (NRC) lab in 1970, at the same time that the last two Sackbuts were being completed, and ten years before polyphonic synthesizers became commercially successful. Each key of its touch-sensitive keyboard had its own pitch control and wave form control. Essentially it was a bank of 37 key-operated oscillators, able to produce 37 separately defined tones.

The Polyphone (860004), Le Caine's early polyphonic synthesizer, had a large and comprehensive control panel.(CSTM)

Above the keyboard were several control devices that were typical of synthesizers at the time: low frequency oscillators, envelope generators, and filters, all of which could influence aspects of the overall sound produced by the instrument. Below the instrument was a pressure-sensitive pedal keyboard that controlled other aspects of the overall sound. The instrument provided extremely comprehensive resources and was potentially a very powerful tool; however, it was difficult to learn to play, a problem it shared with most synthesizers.