Turntable DD or Belt drive. This is the question.

[analog_sa]

I don't recall a figure but from tactile memory the platter weighed well below 500g. It is dwarfed by the inertia of the rotor.

 

[JP]

Considering a 33cm disc 1mm thick of aluminum weighs approximately 923g...

 

[analog_sa]

Considering a 33cm disc 1mm thick of aluminum weighs approximately 923g...

Don't think this is true, more like 230g. The platter is about 4mm thick and has a few holes. Next time i take it out of the cupboard it will be weighed.

 

[wiseoldtech]

Those Thorens TD 124's have a light aluminum platter which sits on a 9+ pound heavy iron sub platter.
I think the total rotational weight is around 11 and a half pounds.

 

[patrickblue]

As do the 150s and 160s.

 

[analog_sa]

They do what? Hard to follow how Thorens were dragged here.

 

[lcsaszar]

The Thorens (at least the TD-160, also others) have a zinc alloy platter of about 3 kg, and a light subplatter of similar material. Not iron and not aluminium for sure.

 

[patrickblue]

The Thorens (at least the TD-160, also others) have a zinc alloy platter of about 3 kg, and a light subplatter of similar material. Not iron and not aluminium for sure.

I think my grey matter is dying off quicker than I thought.
You are quite correct, it was the memory of the two piece platter that prompted my post, but checking both parts are zinc alloy

 

[chip_mk]

It's not the sheer platter mass that counts but the moment of inertia. Between two platters of same weight, one which have more mass on the rim has higher MoI and subsequently better speed stability.

 

[nigelwright7557]

I remember the very old turntables with a stepped idler wheel for 3 different speeds. 33 45 and 78.