M1 Plus+1 Music Workstation © 1989 Korg
the Korg M1 Plus/EX-1 (often referred to as M1 Plus+1 in catalogs and regional bundles) was an expanded version of the landmark M1 Music Workstation. Developed by Korg, it retained the original PCM-based synthesis engine, digital effects, and integrated sequencer, while adding additional waveform memory, expanded preset programs, and improved factory sound content. It was designed to extend the lifespan of the original M1 platform and offer more out-of-the-box sounds for professional and home studio users.
The Plus designation was not a completely new hardware generation, but rather an expanded ROM and factory sound set update to the original M1.
It is often associated with the M1 EX / EX-1 naming depending on region and distribution, leading to some confusion in historical catalogs.
It kept the same core architecture as the original M1, including PCM multisamples, digital filters, and integrated effects.
The expansion focused mainly on increasing preset variety rather than changing synthesis capabilities.
Like the original M1, it supported full multitimbral operation and onboard sequencing for complete song production.
The additional waveforms helped reinforce the M1’s dominance in late-1980s and early-1990s workstation-based music production.
It was widely used in pop, house, film scoring, and early MIDI production environments.
Today it is generally treated as a revision package of the M1 rather than a distinct new synthesizer model.