Polyphonic synthesizer

At the Winter NAMM show in January 1978, Dave Smith and Sequential Circuits unveiled the Prophet-5 to an astonished audience. Here was a polyphonic synthesizer that could play five notes simultaneously, store 40 preset sounds in memory, and recall them instantly at the touch of a button. Before this moment, synthesizer players faced an impossible tradeoff: polyphonic instruments like the Oberheim Four-Voice or Yamaha CS-80 cost as much as a house and weighed over 200 pounds, while portable synthesizers like the Minimoog could play only one note at a time. The Prophet-5 changed everything. Sequential Circuits walked away from NAMM with 400 orders.

The adjacent possible for programmable polyphonic synthesis required the microprocessor. Smith, working as an aerospace engineer at Lockheed by day while building electronic music equipment at night, recognized that the Intel 8-bit microprocessor could manage the complex control tasks that had previously required expensive dedicated circuitry. Each voice in a polyphonic synthesizer needs its own oscillators, filters, and amplifiers—multiplying component count and tuning complexity. By using a microprocessor to scan keyboard input, allocate voices, and store/recall parameter settings, Smith made programmable polyphony affordable.

Smith had founded Sequential Circuits in 1974, initially building sequencers for other synthesizers. His first products were analog and digital sequencers; the Model 700 (1976) could store patches for Minimoog and ARP 2600 users. The Prophet-5 synthesizer emerged from his ambition to build a complete instrument. Originally Smith and John Bowen designed a ten-voice Prophet-10, but instability and overheating forced them to remove half the electronics, creating the more reliable five-voice configuration. Musician Rick Wakeman suggested the name 'Prophet' rather than the prosaic 'Model 1000.'

Why San Francisco? The Bay Area's combination of aerospace engineering talent (Smith's day job), countercultural music scene (synthesizers were central to progressive rock and electronic music), and proximity to Silicon Valley (source of microprocessors and electronic components) created a unique ecosystem. Smith was among the first to recognize that semiconductor technology developed for computers could transform musical instruments.

The convergent emergence was immediate. Oberheim, Sequential's main competitor, had pioneered voice-stacking with the Four-Voice (1975) and Eight-Voice systems, but these lacked programmable memory. Yamaha's CS-80 (1977) offered polyphony and limited preset storage but cost $7,000 and weighed 220 pounds. The Prophet-5 at $4,000 and 40 pounds offered superior functionality in a portable package.

Smith's contributions extended beyond the Prophet-5. In 1981, he drove the development of MIDI (Musical Instrument Digital Interface), the protocol that allows electronic instruments from different manufacturers to communicate. He coined the MIDI acronym and demonstrated it at Winter NAMM 1983 by connecting a Prophet-600 to a Roland Jupiter-6. This standardization transformed the music equipment industry, enabling the complex studio setups and computer-based music production that dominate contemporary music.

The Prophet-5's influence echoes through four decades of popular music. Its distinctive sound appears on recordings from Michael Jackson's 'Thriller' to contemporary electronic music. Dave Smith continued developing synthesizers until his death in 2022, having resurrected the Sequential brand in 2015. The programmable polyphonic synthesizer he pioneered became the template for every hardware and software synthesizer that followed.