The SP-10 was the world's first turntable to use a direct-drive system. With the direct-drive system, the motor rotated at the same speed as the record; therefore, there was no speed reducing mechanism, such as a belt or idler. As a result, mechanical vibrations originating from the speed reduction mechanism were nonexistent. The turntable platter weighed 2.8 kg and had inertial mass of 330 kg-cm2. Every platter produced was meticulously adjusted for optimal dynamic balance. Since the spin speed was electronically changed when the dial was operated, there was no switching mechanism to cause rotational fluctuation. The rotation speeds of 33-1/3 and 45 rpm were individually fine-adjustable. The SP-10 was used by the BBC and also evaluated highly around the world. It became a de facto reference for Hi-Fi record players.