WM-51

The WM-51 is a compact playback-only cassette Walkman released in 1987, built around the same basic chassis as the earlier solar-powered WM-F107 but reworked into a simpler everyday model. It combined auto-reverse, Dolby B noise reduction, and a retractable earphone system that wound into a rear compartment through a dedicated wheel, keeping the unit self-contained without loose cords or attachments. A metal internal frame supports the plastic shell, while the exposed rear volume control, hold function, and cassette door catch system gave it a slightly more engineered feel than its modest positioning might suggest.

This model makes sense once the Walkman had become ordinary enough that convenience itself could be a selling point. Sony was no longer trying to wow buyers with radical hardware, but with compact reductions in friction: fewer loose accessories, less cable clutter, fewer reasons to think about the machine when heading out the door. The WM-51 is a commuter's Walkman in the most literal sense.