Belt-drive turntable

Many belt-drive turntables with multiple speeds have mechanical devices or rely on manual effort to move the belt between different-sized pulleys on the motor shaft.

Due to the existence of instabilities of mains electricity, manufacturers might try to ensure pitch stability by generating its own sinusoidal waveform to power their AC motor.

Some turntables, such as the newer versions of the Rega Planar series, use a fixed plinth with a low vibration motor and bearing attached to the same flat surface, usually constructed of wood, metal or acrylic, without suspension.

[1] The principle behind it is that the turntable is an inert platform that allows the stylus to track the surface of the record accurately whilst being protected from external vibrations.

The platter, sub-chassis, armboard and tonearm mechanically form a closed loop, and sit on top of dampers (usually three springs) which isolate the sub-assembly from its motor and its base.

[1] A variation can be found in the Oracle Delphi, where the spring is extended;[2] another variant is the Roksan Xerxes, whose top plate is isolated from the motor bearing assembly by compliant rubber dampers.

The main disadvantage of belt-drive turntables is the fact that they "ramp" to tempo; they do not instantly play the record at 33 1/3 revolutions per minute, but rather build up to this speed over the course of about one second.

The functional relationship between the drive belt, sub-platter, and motor pulley, can be seen through the glass platter on a Rega Planar 3 .