Direct Drive vs. Idler Drive vs. Belt drive


I'd like to know your thoughts on the strengths and weaknesses of each drive system. I can see that direct drive is more in vogue over the last few years but is it superior to the other drive systems? I've had first-hand experiences with two out of the three drive systems but looking to learn more.
128x128scar972
Miyostin,
you are right comparing air bearing and magnetic designs.
nevertheless what counts are bearing hardness, batch braking moment and energy transmission by the bearing.

E.
has2be

I was merely (re)stating an inherent advantage of a DD design with respect to its bearing, after all the OP has asked this.....
"I'd like to know your thoughts on the strengths and weaknesses of each drive system"
I did not say that overall DD is superior. 

An inverted bearing is inherently more stable, on that I hope we agree?
My comment about the shaft finish is simply engineering 101. In the outside world it is common to not polish a sleeved oil lubricated bearing. This for the reason I raised. I know of one, possibly 2 TTs that use the non polished technique, both have well designed and engineered bearings. . These are the Final Audio Research and the big idler EMT. These TTs have very quiet bearings thru good engineering not bias 

Sure you can remove horizontal pull on a BD  bearing by having 180 degree opposed motors or an idler. That said, one would need to be very careful not to introduce noise into the platter from the second (or third) rotating element.

All TT drives have strengths and weaknesses, there is more than one path to enlightenment. On that we agree. I prefer DD, that is my opinion, others do not. I'm fine with that. 

 My experience is that it is by far the hardest to achieve good performance from a DD design. This because there is no filter between the drive and the platter. Any aberrations in the drive are exposed warts and all. This is particularly difficult if the designer chooses a high motor torque to platter inertia ratio. Difficult but not impossible. 


Cheers 
 
@richardkrebs 

Actually, Richard. Your mistaken in that I was even referencing you or your comments . The only thing I would reply to a polished shaft as a fault would be if rifling was encorperated to draw the oil upwards such as michell does would negate your view of it.
My point was and always is there are more ways to get results than the narrow view of biased ownership. 
Clearly, you don't fall in the blind bias and I know you did not state DD was superior nor did I suggest you did or do. Please reread and you will see whom ALWAYS does as in this thread.
Your last statement on why DD is more difficult to do and although not impossible is fewer than those that don't  was refreshingly pleasing to read.
None of us hear the same either complicating our opinions wrapped in facts that have as many variables changed with design and implementation from one to the next.
Believe me, I certainly wasn't referencing anyone who ever articulated what you last posted. Cheers
IMHO belt drive have a huge drawback that idler drive and DD don’t have.
Belt drive doesn’t hold speed stabile and as result ruins the PRAT.
And it is much more important drawback than bearing noise.
No PRAT - no music!