Wow & Flutter Explained

The Sony Walkman, the iconic portable cassette player, wasn't immune to the issue of wow and flutter. Wow and flutter refer to the unwanted speed variations during audio playback, leading to fluctuations in pitch. These variations can arise from various factors such as off-center records, worn-out belts, or sticky cassettes.

The Walkman's wow and flutter specifications, measured in percentages, were generally reported using either the DIN or JIS method. The DIN standard, commonly used by European brands, employed a quasi-peak detector that heavily emphasized the "wow" component (slower variations) and gave less weight to the "flutter" component (faster variations). Japanese brands often used the JIS method, which employed a root mean squared (RMS) detector and averaged the measurements over a longer period.

For high-fidelity cassette decks like the Walkman, the DIN standard recommended a weighted wow & flutter of no more than ±0.2%. To put this into perspective, a 5% difference in playback speed results in a pitch change of one semitone. The first Walkman model, the TPS-L2, boasted a wow & flutter of 0.219% (RMS), considered quite good and almost unnoticeable.