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Turntable construction

Turntable construction

Inexpensive record players typically used a flanged steel stamping for the turntable structure. A rubber disc would be secured to the top of the stamping to provide traction for the record, as well as a small amount of vibration isolation. The spindle bearing usually consisted of a bronze bushing. The flange on the stamping provided a convenient place to drive the turntable by means of an idler wheel (see below). While light and cheap to manufacture, these mechanisms had low inertia, making motor speed instabilities more pronounced.

For the serious listener, turntables made from heavy aluminum castings were offered. Typically, they were machined on a lathe and balanced, operating with negligible vibration. Like the stamped steel turntables, they, too, were topped with rubber. Due to the increased mass, they usually employed ball bearings or roller bearings in the spindle for low friction. While some used idler wheel drive, most were intended for belt or direct drive. The high mass and inertia of such turntables helped keep the speed constant, even if the motor exhibited cogging effects.