While I agree with Doug's comments I also agree that they may be a bit oversimplified. As is often the case it's all about compromise. A stretchy belt does have all of the problems that Doug points out. But the flip side is that isolation from motor cogging and noise is also very important. For a given motor and platter combination there will be an ideal amount of coupling. And that ideal will vary widely.
The important factor is how much cogging the motor exhibits. When you start with a motor that has low cogging the motor can be more intimately coupled to the platter resulting in some major benefits. Motor isolation is only good if it solves a bigger problem than it creates. Much better to start with a motor that does not need isolation, or at least very little.
It's a similar compromise when it comes to torque. High torque is a very good thing when it is tightly coupled to the platter. It's the only effective method for eliminating the effects of stylus drag. The higher the torque the better. However, in the real world higher torque (good) almost always comes with higher cogging (bad). So as Thom pointed out the challenge is to find an ideal compromise. As with isolation using a motor with lower cogging moves the ideal torque higher with it's associated sonic benefits.
A good unsuspended table addresses the problem of floor and room vibration. It just does it differently than a suspended table. This is a common misconception. There is a big difference between "high mass" and "highly damped". Simply making a turntable heavy is useless and often makes resonance problems worse. A highly damped turntable is able to dissipate vibrational energy internally. So external vibrations are allowed to reach the turntable but are then dissipated once they arrive. The big difference is that energy emanating from within the turntable is also dissipated in a highly damped turntable. It is important to have a mechanism for dissipating internal energy as well as energy from external sources. Suspension has both beneficial and detrimental effects. And like motor isolation is only good when it solves a bigger problem than it creates. A highly damped turntable needs less isolation so in many (but not all) cases isolation ends up being detrimental. This is why most highly damped turntables tend to be unsuspended.
Chris
The important factor is how much cogging the motor exhibits. When you start with a motor that has low cogging the motor can be more intimately coupled to the platter resulting in some major benefits. Motor isolation is only good if it solves a bigger problem than it creates. Much better to start with a motor that does not need isolation, or at least very little.
It's a similar compromise when it comes to torque. High torque is a very good thing when it is tightly coupled to the platter. It's the only effective method for eliminating the effects of stylus drag. The higher the torque the better. However, in the real world higher torque (good) almost always comes with higher cogging (bad). So as Thom pointed out the challenge is to find an ideal compromise. As with isolation using a motor with lower cogging moves the ideal torque higher with it's associated sonic benefits.
A good unsuspended table addresses the problem of floor and room vibration. It just does it differently than a suspended table. This is a common misconception. There is a big difference between "high mass" and "highly damped". Simply making a turntable heavy is useless and often makes resonance problems worse. A highly damped turntable is able to dissipate vibrational energy internally. So external vibrations are allowed to reach the turntable but are then dissipated once they arrive. The big difference is that energy emanating from within the turntable is also dissipated in a highly damped turntable. It is important to have a mechanism for dissipating internal energy as well as energy from external sources. Suspension has both beneficial and detrimental effects. And like motor isolation is only good when it solves a bigger problem than it creates. A highly damped turntable needs less isolation so in many (but not all) cases isolation ends up being detrimental. This is why most highly damped turntables tend to be unsuspended.
Chris