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Turntable weight affects speed

I tried a Thorens tt weight on my Thorens TD-850 belt-drive tt. It noticeably slowed it down.  It seems like extra weight on the bearing would affect any tt, but what do I know?  Is a speed control (and strobe/test pattern) generally required to use a turntable weight while maintaining the proper speed?

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Showing 2 responses by testpilot

testpilot
896 posts
 

Since the record weight is positioned over the axis of rotation, the added mass does not substantially affect platter’s rotational inertia, therefore, your motor should have sufficient torque to start and maintain platter speed. 

testpilot
896 posts
 

To add more context to the discussion, the OP’s platter weighs 4kg and the record weight is 291g - a 7.3% increase in mass which is positioned right over the axis of rotation.  I highly doubt that very slight increase in rotation inertia is causing the ac motor falling out of synchronous speed. I would look at lubrication and belt wear as the potential cause.  

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