WM-507

The WM-507 is a wireless playback Walkman that separated the cassette transport from the listening interface, with the main body acting as the player and transmitter while a smaller receiver handled audio output and basic control. It supports auto-reverse, Dolby B, and Extended Dynamic Bass Boost, while also allowing wired headphone use directly from the main unit if needed. Sony reduced the receiver's size by using a smaller rechargeable battery, making the wireless side of the system easier to carry and less awkward in practice than earlier versions.

This model shows Sony treating wireless more than as a novelty, but as something that had to become livable. Earlier wireless Walkman had already proven the idea was technically possible, but the 507 feels more concerned with whether the user would actually want to keep carrying the receiver every day. It sits within that transitional phase where portability was no longer simply about removing the cable, but about making the whole system less annoying.