WM-F507

The WM-F507 extended the WM-507 wireless cassette system by adding FM radio, but did so in a way that kept the main cassette body largely unchanged. As before, the player unit handled playback and RF transmission, while the smaller receiver took on the role of both listening device and radio interface, including tuning and control. On the cassette side it retained auto-reverse, Dolby B, and Extended Dynamic Bass Boost, while keeping the same compact rechargeable receiver layout as the non-radio version.

Sony is still trying to figure out where "the player" actually ended once listening became wireless. By pushing the tuner into the receiver instead of the cassette body, the company treated portability as something distributed instead of centralized. It reads as one of those models where the format itself is being rethought.