Sony WM-EX674 Motor

The Sony WM-EX674 uses a disc motor for the tape drive. A motor such as this is brushless and moves in discrete amounts. It requires a driver integrated circuit (IC) to control it. The magnet and coil assembly of this motor are less than 4 mm in depth, which is remarkable.

Compared to the WM-EX610, this model has a dedicated driver IC, which is able to conserve more power. Usually, the motor consumes the most power since it is an electromechanical device, however, the driver IC powers the motor in very short pulses that is just enough to maintain the torque and keep the tape moving at a constant speed. There is also an extremely sensitive closed-loop servo, which maintains super smooth speed. All of this technology allows the player to operate for up to 39.2 hours on a single AA battery.

Motor Driver IC

The small chip you can see in the picture is the motor driver IC. It is extremely efficient and can power the disc motor for many hours on impulse drive. In addition to driving the motor, it also manages the power, and has the circuitry for a closed loop servo to regulate the speed.

These motors pull the tape at an extremely smooth and constant speed, and you can tell straight away that the player is something special. Certainly, if you have been listening through a cheap and nasty DC brush motor with a wobbly speed then, this player makes a big difference.

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