The WM-DD was a combination of three excellent ideas in one desirable machine. It took the compact chassis and electronics of the WM-2 and combined them with the disc drive capstan servo principle that was first seen in the TC-D5. To complete the package, the case from the WM-5, made from pressed metal instead of the moulded plastic, was used. This was changed slightly, in as much as the little window through with the volume scale could be seen was deleted. Text copyright © Walkman Central. Unauthorised reproduction prohibited.
The DD mechanism had to be miniaturised and simplified to fit into the tiny chassis, so some compromises were necessary. Most importantly, the drive wheel of the motor was not disengaged from the rubber tyre of the capstan when the tape transport was in “stop” mode. This meant that if the machine was left unused for long periods an indent could form in the rubber, leading to an irritating cyclic speed jerk. Regular use (no hardship!) was the only answer. Because the DD system used a tacho sensor inside the capstan flywheel, there was no longer a need to have a servo pickup inside the motor. The WM-DD used the same basic motor as the WM-2 however, so the leads to the pickup were simply cropped off. Full automatic stop was retained, though its functioning in the winding modes worked in a new and interesting way. When the tape reached its end, the flywheel (which drove the tape reels through gears) could no longer turn, despite the best efforts of the motor. In this condition, the servo could no longer “lock” and if this situation remained for more than a few seconds the power to the whole machine was cut. Because of this refinement, the optical sensor on the take-up spool was no longer required. Text copyright © Walkman Central. Unauthorised reproduction prohibited.
The new arrangement resulted in a useful reduction in wow and flutter and an increase in speed stability generally. These factors were of great value to the serious listener and the WM-DD can be considered as a major step forward in the quality of personal stereo cassette players. The only thing lacking was Dolby NR, but this omission was addressed in the next model, the WM-DD2. Text copyright © Walkman Central. Unauthorised reproduction prohibited.