Direct drive/rim drive/idler drive vs. belt drive?

I would just like to add my five-penneth.

Aren't the idler wheel and belt drive systems completely differing technologies/sciences? On the one hand (Belt) you have a large mass in rotation, a motor that only really pushes when the platter slows, and a flexible drive system (belt). One the other (idler) you have a clamp sytem where the idler wheel (inside rim) pushes the platter away from the centre bearing or (outside) pushes the platter towards the bearing. The platter is trapped between the bearing and the idler. (Depending where you are standing both idler types are the same.)

I don't see how a comparison can be made. They are just different and both work well or badly depending how well they are engineered and built.

:-)

Mark: I am no expert but my experience is that the heavier the platter on the belt drive T/T the more likely we are to have less variations in speed. I owned a Michell Gyrodek for some years and always knew that its speed stability was marginal. It wasn't until I purcahsed my present Acoustic Signature Analogue One Mk 111 that I realized how bad the Gyro had been. I know that things are relative. I have to assume that both decks are well engineered within the requirements of each design. I am inclined to believe that the real reason that the AS is better is because the platter has higher mass. I am not aware of how heavy the platters are on idler T/T's but would make an educated guess that they are much less than the AS which I will use as my reference.

In the case of the idler T/T at no point is the platter allowed to rotate in a 'free' state. The idler drive is always in contact and driving, even if we admit that there IS some compliance in the rubber driving material.

I stand by my firtst statement that the two systems are completely different and both can work or fail. It's really only about engineering.

Clarkie