Yamaha · 1988 · 1980s–1990s · 6 voices
The YM2612 gave the Sega Mega Drive six channels of 4-operator FM synthesis, producing the warm-metallic, harmonically complex sound that composers like Yuzo Koshiro turned into some of the finest electronic music of the 16-bit era.
The YM2612 (OPN2) was a six-channel FM synthesis chip providing 4-operator synthesis per channel with eight selectable operator connection algorithms. Channel 6 could be switched from FM synthesis to an 8-bit PCM sample mode, enabling digitised speech and sound effects at audio quality the FM channels alone could not achieve. FM synthesis required deep knowledge to program — operators, carrier/modulator relationships, envelope parameters, and feedback ratios interacted in non-obvious ways — but composers who mastered it produced a metallic, electroacoustic timbre unlike anything in sample-based synthesis. Yuzo Koshiro bypassed Sega's standard music driver for Streets of Rage 2 (1992) and wrote his own, pushing the chip's rhythmic and timbral capabilities to produce music that functioned as genuine dance music. The Genesis pairing of the YM2612 with the Texas Instruments SN76489 PSG added three square-wave channels and noise for a total audio system of remarkable range.