Oversize platters

The oversize platter myth

Turntable platters with a bigger diameter have greater rotational momentum. That is a fact. But some companies claim that a slightly bigger size gives double momentum of rotation with the same mass. That is just not correct. Let us assume that the platter is a cylinder without being narrower at the outer edge, then:

Platter mass X                              size   30 cm              size   33 cm       size   43cm

Momentum of inertia                       225                        272,25                462,25   ( value for compare)

A larger platter with the same mass will, of course, be thinner than a smaller sized platter. The thinner platter will resonate more - that is also a fact.

We can see that increasing the diameter by 10%( from 30 to 33 cm), gives only 21% and not double, increase in momentum. If, for example, two platters are made the  same mass of 8kg,  from the same material, then the platter with a diameter of 30 cm will be 4cm thick and  43 cm sized platter will be only 2 cm thick. You can easily judge by yourselves which will ring more. We do not want a platter that acts like a cymbal. 

So optimal size and thickness of a platter, together with the damping properties of the material used and its internal construction is the best way to make the best possible platter.