What Type of Belt is Used and Why?
The MS turntable uses a flat drive belt. We chose a crowned pulley rather than a belt guide to center the belt since we found that belt guides generate noise. Also, a flat belt on a crown pulley is self-centering. Therefore when changing speeds it will automatically run straight. In experimenting with round and V belts we found these belts to generate noise by scrapping the sidewalls as they enter or leave the pulley groove. The belt’s length and type of material make what we call its critical elasticity. The drive belt has two functions; one is to drive the platter via the motor and, two to act as a filter. The first chore of the belt is fairly simple, the second not so simple. If the belt is too long the platter can oscillate excessively and wow is enhanced. A similar consequence occurs when a weight is hung from a rubber band. The longer the rubber band the springier it will be. The belt also acts as a low pass filter (the belt can also vibrate in sympathy with motor impulse if not
