Polyphonic Synths and the Dawn of MIDI — Chords, Memory, and Connection

Two Walls — Chords and Memory

The Minimoog (Article 4) brought the synthesizer to the masses, but two walls remained:

1. It couldn’t play chords — it was monophonic, one note at a time
2. It couldn’t remember its sounds — a carefully crafted patch would vanish the moment you turned a knob. Every session meant starting the settings from scratch

The instrument that solved both problems at once was the Prophet-5, released in 1978.

Prophet-5 (1978) — Polyphonic + Preset Memory

The Prophet-5, announced by Sequential Circuits under Dave Smith, was a double revolution:

• Polyphonic — five notes could sound at once. At last, a synth that could play chords
• Preset memory — a built-in microprocessor let players save and recall the sounds they created in memory (a feature that overturned the conventional wisdom of the time)

Being able to save the results of sound design turned the synthesizer into “an instrument that could switch sounds instantly on stage.” The Prophet-5 was used extensively in 80s new wave pop and established the standard for the polyphonic synth.

The Golden Age of Analog Polysynths

Around the time of the Prophet-5, each manufacturer released its own distinctive flagship instrument. This was the peak of the analog synthesizer:

• Roland Jupiter-8 (1981) — a thick, brilliant sound. A staple of 80s pop for artists like Duran Duran and Howard Jones
• Yamaha CS-80 (1977) — weighing over 100kg. Expressive performance through polyphonic aftertouch. The sound of Vangelis’s Blade Runner
• Roland Juno series — an affordable, warm sound with built-in chorus. Widely adopted
• Oberheim — known for its thick brass sounds

Each instrument had its own distinct character, and a bond formed between artists and machines — “that artist’s sound is that instrument.” Legendary machines came to define entire musical genres — a phenomenon unique to electronic keyboards.

MIDI (1983) — Crossing Manufacturer Boundaries

Behind the analog heyday, a decisive standardization effort was underway. The problem was that each manufacturer used its own incompatible specifications, making it impossible to connect instruments to one another. The solution was MIDI (Musical Instrument Digital Interface).

• Established in 1983 — led by Dave Smith (Sequential) and Ikutaro Kakehashi (Roland), with agreement across manufacturers
• Performance data is exchanged as a digital signal — sending information like “which key, at what strength, was pressed or released, and when”
• This made it possible to play multiple sound sources from a single keyboard, perform automatically via sequencer, and synchronize equipment

The key point is that MIDI is a standard for sending “performance instructions,” not the sound itself. This made it possible to separate the keyboard (controller) from the sound source, laying the foundation for DTM (desktop music) — assembling music on a computer. MIDI remains fundamentally backward-compatible to this day, a remarkably long-lived standard in the history of music.

The End of Analog, and a Sense of the Digital to Come

1983 was a symbolic year. In the very same year that MIDI was established and instruments began to connect — an instrument appeared that would instantly turn the golden age of the analog polysynth into the past: the Yamaha DX7.

Against the thick, warm sound of analog, the DX7’s FM synthesis produced a hard, glittering sound that was entirely new and digital. And it was affordable, its pitch was perfectly stable, and it came with a huge bank of built-in presets.

The next article traces the DX7 and the FM digital revolution — the moment electronic keyboards leapt from “voltage” to “computation,” and completely repainted the sound of 80s pop.