Does the number point to an early 1988 build or a later 1991 build?

What the serial number indicates

The Korg M1, released in 1988, is the best-selling digital synthesizer of all time. Whether you are a collector, a gigging musician, or a vintage gear flipper, tracking the is the best way to verify the age, origin, and authenticity of your unit.

The serial number is located on a white sticker or directly embossed/stamped on the of the Korg M1 unit, typically near the power switch or audio outputs, as shown in user vintage synth forum discussions . Look for a small black/silver or white label.

In the pantheon of electronic musical instruments, few devices command the respect and historical significance of the Korg M1. Launched in 1988, this workstation synthesizer is the single best-selling synthesizer of all time, with over 250,000 units sold. For the modern collector, vintage synth enthusiast, or working musician using a 35-year-old piece of gear, the small, often-faded sticker on the bottom panel—the serial number—is a portal to a wealth of information. Far from a mere inventory tag, the Korg M1’s serial number is the key to unlocking the instrument’s manufacturing date, hardware revision, geographic origin, and even its potential for specific sonic characteristics or reliability issues.