WM-B39

The WM-B39 is part of the earliest Walkman to carry Sony's Mega Bass branding, pairing the new low-end enhancement with simple bass and treble equalization controls, Dolby B noise reduction, and auto-reverse playback in a compact portable body. The layout stayed practical and readable, with the sound controls exposed instead of hidden, giving the machine a more obviously "sound-conscious" identity than many of the plainer budget players around it. It still remained fairly compact and everyday-friendly underneath.

The B39 sits at the moment Mega Bass began moving out of isolated higher-end machines and into a wider, more affordable part of the Walkman line. That signals a real shift in how Sony was selling portable sound by the late 1980s: fidelity was only part of it, and immediately noticeable listening character counted too. It was a compact but meaningful branding turning point.