Record clamp/weight and turntable speed

Get an Ap called "RPM" on your phone and see for yourself. If your turntable is DD or using an AC synchronous motor it should not matter.
It should also not matter with a well controlled DC motor. In Short, If it does change your turntable's speed it is junk, throw it away and start over. If the weight is changing speed so is groove friction which varies.

Hey all. So today I thought for the first time if having a substantial weight or clamp on the spindle affects the platter rotation speed. It doesn't for me, as far as I can tell, but if not, why would that be so?

It can happen ONLY with belt drive turntable!

For Direct Drive this problem is irrelevant and not exist even with high mass platter mat + heavy record weight or clamp. 

This is by far the best clamp/weight I even owned!  

Enough torque will be fine for additional weight.

G

@chakster , speed fluctuations can happen just as easily with a poorly designed DD table as with a poorly designed belt drive. Well designed tables of either type do not have this problem at all. The only thing you can say about the DD turntable is it will start up almost instantaneously and sound universally horrible:-)
It is not at all a matter or torque. It might take a little longer for a low torque table to get to speed but that is all. Once the platter is in motion it takes very little torque to keep it going. Even the lowly AR XA runs just fine with a record clamp.

@mijostyn  The “sound” of a turntable drive is BS, you hear the sound of cartridge/tonearm mainly. The rest is speculations. Speed must be stable, period.
Even very cheap direct drive can’t be affected by the weight of a record clamp.
Not every Direct Drive have a high torque and immediate start at constant speed. Not every DD have a high mass platter. My luxman pd-444 or Victor TT-101 are not high torque turntables.
Technics is a high torque turntable, even if you put 3kg on the platter the rotation will be stable with immediate start!
Belt drive can be affected by many factors and the speed is the main issue, read tons of comments on audiogon from BD turntable owners, those type of drive is notorius for not stable rotation. Most of BD turntables on the market is junk and people love it!