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

O.K. here is one for all the physics majors and engineers.

Does a high mass platter being belt driven offer the same steady inertia/speed as a direct drive or idler drive?
Is the lack of torque in the belt drive motor compensated for by the high mass platter. Object in motion stays in motion etc. Or are there other factors to take into consideration?
I am considering building up a Garrard 301 or Technics SP10, but is it all nonsense about the advantage of torque.
I am aware that the plinths on these tables can make a huge difference, I've got that covered.
My other options would be SME20 or Basis 2500 of Kuzma Stogi Reference etc.
If I have misstated some technical word, please avert your eyes. I don't want a lecture on semantics, I think everyone knows what I mean.
Thanks in advance.
mrmatt
albertporter's avatar
Ag insider logo xs@2x
albertporter
4,927 posts
 
Excellent story, mine is much simpler.

My Mother and Father picked out Albert Porter for me when I was born and it seemed like a good name for Audiogon as well :^).
mosin
410 posts
 
While we are getting offtrack...

Mine comes in memory of Colonel Sergei Ivanovich Mosin. He had a fascination of mechanical things enough that the rifle bearing his name has survived from 1891 til this day in one form or another. I respect him because he fully appreciated and practiced the principle "form follows function" even before Louis Sullivan wrote about it.

Win
mosin
410 posts
 
Back on track...

The discussion so far has been about torque, but in my opinion the most critical component of a turntable may be the platter. With all three types, belt driven, idler driven and direct drive, the platter can be the make-or-break piece because it is the final interface to the record, it is key to how inertia works and it is the interface to the rest of the mechanism. That said, I really believe that a turntable should be seen as an entity because, like the audio chain in your system, it is only as good as its weakest link. There is no single part, no matter how seemingly insignificant, that should be overlooked. Designing a decent one is easier said than done for certain.

Win
quiddity
119 posts
 

And to take that theme and refer back to the OPs question, I might ask: how much of the total inertia of the system should the platter represent? What influence does splitting some or most of the inertia away from the platter have on the perceived "drive" of the system?

It seems to me that many of the designs which are known for having lots of what Albert calls "drive" have moderate mass / moderate inertia platters tightly coupled to a high inertia drive system. If I'm not mistaken Win had a similar concept in mind when he desgned his TT.

Mark Kelly
hiho
451 posts
 
Platter is important but in my experience the motor is the most important and then combination of platter and bearing. After all the motor is the active component here, hence it's called TURN-table for a reason. It has the most demanding job and requires the most sophisticated engineering that involves electrical and mechanical skills. If you get a good motor, you are more than half way there. Of course, if you use a soft rubber belt to conceal the flaws of the motor then the platter is more important. I do agree that a record player should be seen as a whole system not just a collection of parts.
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