WM-504

Sony explored a more design-focused direction with the WM-504, using a high-hardness transparent resin enclosure that exposed the transport, tape motion, and cassette shell. Instead of hiding the mechanism, the model turned it into a visual feature, emphasizing the precision of the internal layout.

The transparent housing required a formulation that balanced clarity with strength, and it pushed Sony to arrange components more intentionally than on opaque units. The design was led by Takashi Sogabe, whose later work on the EX series expanded ideas first explored here: clean surfaces, compact proportions, and tighter integration between form and mechanism.

The model was positioned for listeners interested in material quality and presentation as much as audio performance. A desktop charging base supported that shift by presenting the player as a personal object rather than only a portable device.

While its commercial impact was limited, the WM-504's design language played a larger role than its sales. It helped set the direction for the refined, material-driven Walkmans that followed.