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  HOME  : Grado Laboratory Turntable :  Design
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The Laboratory turntable is a unique design, unlike any other table of the era. Dual platters connected by a central shaft were employed in place of the standard single platter. The upper platter is the playing surface for the record, while the lower platter acts as a massive flywheel to store rotational energy. The flywheel effect ensures that variations in speed are minimal.

In order to drive the mass of the dual platters, two 12-pole hysteresis synchronous motors are used. Typical turntable motors used 4-pole motors. By tripling the number of poles to 12, Grado achieved incredible speed stability.

A drive belt is used to couple the motors to the lower flywheel platter. Belt-drive offers the advantage of decoupling motor vibration from playing surface preventing it from being amplified by the phono cartridge.