VPI TNT Turntables

I agree that flywheels are a benefit, provided they are constructed properly for the task at hand.  Usually, the flywheel is larger in both diameter and mass than the object it is trying to stabilize.   Increasing mass does help, increasing radius helps much more.   In the case of the VPI flywheel, it is both smaller and lighter than the platter.  I would guess 20% increase of inertia improves stability by 20% as well, all other things being equal. If that explains the improvement in SQ, then mystery solved. If 20% improvement is acceptable for the added cost, then it's a worthwhile investment.

I agree that anything that improves the speed stability of the platter is a good thing. I don't know that adding another pulley (flywheel) and another belt is "faulty", but it bears investigation. All belt drive systems suffer from belt creep which affects speed accuracy and stability. In theory, having two belt drives in series would make belt creep worse (vs 2 belts in parallel around 1 pulley and 1 platter which should make things better), but I haven't measured it.

>FYI, a properly designed speed controller will provide excellent instantaneous
>speed stability, but long term speed accuracy is improved with feedback.

Can you perhaps recommend one? =)

I assume your of the Phoenix speed controller fame due to your feedback comment?

Fwiw I would rather have continuos speed than ever changing speed. But we've gotten into this before. 
The ear will detect changes much more easily than a controller that is slightly off but the same all the time. 

Constant motor speed does not equate to constant platter speed however.

Would you rather have constant motor speed with constantly changing platter speed, or motor speed that changes to keep the platter speed constant?