The Sony WM-DD is a part of the early Walkman series, specifically focusing on portable audio cassette players. Launched in 1982, this model features a 'disc drive' mechanism, where the main motor is directly coupled to the capstan flywheel assembly. This direct drive technology ensures remarkably stable playback speeds and low wow and flutter levels. The device has body dimensions of 79 x 109.2 x 29 mm and weighs 290 g with batteries. Powering the unit can be achieved via two AA batteries, an AC adapter, or an automobile adapter. The WM-DD offers a battery life of approximately 4 hours with manganese batteries and 9 hours with alkaline ones. Key specifications include a maximum output power of 20 mW for each headphone output, a frequency response range of 40 Hz to 12 kHz for normal tape, extending up to 15 kHz for metal/chrome tapes, and a wow and flutter measurement of 0.08% WRMS. Accessories that are compatible include the MDR-W5 headphones. Subsequent models in the series, such as the WM-DD2 and WM-DD3, built upon this design with added features like Dolby B noise reduction and quartz crystal lock for enhanced playback stability.
