High mass vs Low Mass Turntables - Sound difference?

Avanti, On many counts, your analysis is not entirely correct.  Without going through all the arguments, if you like belt-drive you want the pulley and the platter to be as similar in diameter as practical, and as close together, center to center, as practical. This reduces belt-creep and enhances transfer of motor torque to the platter.  Also, why does having a small pulley driving a large diameter platter prolong motor and bearing life? The motor has to spin faster in inverse proportion to the ratio of the diameters of pulley and platter, which I would think would tend to shorten motor life.  Ditto for the bearings, especially the motor bearings. Belt life; that's a toss-up.  But just the fact of using a belt places side stress on both motor and turntable bearings.

@lewm 
a smaller motor pulley driving a larger pulley (platter vs. sub platter) has many engineering advantages as can be computed in simple belt pulley - pulley drive system configurations.  i performed some engineering calculations simulating a 1" motot pulley driving a 12" platter vs. driving a 4" sub-platter.  Below are the findings:

1) Bearing force. The platter driven system has a bearing load force of 2.8 lbs. The sub-platter driven system has a bearing load force of 6.7 lbs. or 240% more load. More than twice the force on the bearing means increased wear, noise but more importantly increased drag on the speed of the platter. 

2) Cyclic Variation (in belt tension). The platter driven turntable has a cyclic variation of 0.79 lbs. The sub-platter driven turntable has a cyclic variation of ~2.4 lbs, over (3) times as much as the platter drive. 
Because the motor and belt in the sub-platter system have to work harder to spin the platter, the tension on the "pull" side is much less than the tension on the "slack" side of the belt. This translates into constant pull / release tension cycling and stretching which will wear out the belt significantly faster than the relatively light belt stretching on the platter driven turntable. 

3) Drive ratio. How many revolutions the motor pulley spins in relation to the speed of revolutions of the platter. The platter driven drive ratio is 0.083 while the sub-platter driven system drive ratio is .25, or 3X as much. What this means is that speed variations in the motor of the sub-platter will be magnified 3X as compared to speed variations in the sub-platter motor. In other words, a speed variation of 1% in platter driven system caused by the motor will equal a 3% speed variation in the sub-platter system, all else being equal. A platter driven system has 3X the speed stability of a sub-platter driven system.

4) Drag resistance. This is a simple lever arm calculation. The larger pulley (12" diameter pulley) compared to the sub-platter (4" diameter pulley) has a 3X greater resistance to drag forces. Drag forces in the form of tone arm drag (minimal but measurable) and bearing drag. Bearings are not frictionless. But because the bearing forces are 2.4X higher in a sub-platter system, it has more drag to overcome and 3X less capability to do so. In effect, the sub-platter system is 5.4X more sensitive to drag caused speed variation than the platter driven system.

Summing up. The combination of much higher bearing load forces, belt tension variation, 3X more speed variation sensitivity and 5.4X more sensitivity to drag forces place the sub-platter system with a significant amount of physical and mechanical disadvantages when compared to a platter driven turntable. It's refreshing to see that the high end turntable manufacturers actually have some sound engineering and physics principals to back up their designs.   

I recently heard the Rega RP 8 and was very impressed.  I actually think it is a better table than say the VPI prime and Classic.  I believe the scout actually sounds just about as good as either of these tables.  The problem with VPI is their arms.  Unless you use a moving magnet or moving iron cartridge, you will run into tracking issues because there is no real anti-skate mechanism with their arms.  Not good when you are running a low output moving coil cartridge that magnifies everything so much, you need an arm that will not fight the tracking of the cartridge/stylus.  I think the founder of VPI does not really believe in anti-skate.  Well, i guess if you use an aries with a 12 inch arm that probably helps a little.  But if you do not have a 12 inch arm, you NEED antiskate.  The Rega tracked much better than the prime or the classic and really digs into the grooves.  Amazing table for the money.  The only thing I do not like is it is too plug and play.I am not sure their cartridges are the best and I believe their arms are worthy of much better.

Tzh21y, you and I are hearing the same thing. The Rega has this incredibly clean, detailed and fast sound. 

I never liked the VPI arms either and they are a pain to setup.

Also the VPI drive system always has a bit of noise as you can hear the round belt riding in the crown of the pully unless they changed that I always thought that was a design difficency of that design.

I will disagree with you on your last part, the new Rega Alpheta 2 is a remarkably good cartridge, it is way better than the 1rst gen Alphea.

For the first time Rega is actually getting raves on their cartridges. 

The exact and bias do sound good for the money but lacked some of the midrange bloom of some of their competitors.

The new Alpheta 2 and the new Anima cart are really quite special.

Dave and Troy
Audio Doctor NJ