Direct Drive vs. Idler Drive vs. Belt drive

"I did different thing and it’s not just about mass, because the SP-10 MKII does not have additional layer of the different material on top surface of platter as mk 3 model so i just used Micro Seiku CU-500 to upgrade it.

As the result, the platter made from one material was decoupled by gunmetal mat (material with different properties and different resonance). This is more like upgrading mk2 model looking at next mk3 model. There was the reason why Technics decided to add another later on top of the platter. So i had a gunmetal between the platter and vinyl record.

I asked why you just replaced original platter, because every Technics platter is balanced and there is a stamp about it. I have no idea who made the platter you’ve been using, maybe it was a bad platter (i mean not as good as the original) ? Increasing mass on Technics platter with gunmetal mat was huge improvement, but maybe not just because we add mass. This is what i want to say.

And another example is Kodo The Beat turntable, based on Technics motor, look at the Kodo platter.

Also nearly all turntables from Artisan fidelity comes with their own copper mats on top. Even tweaked Technics MK3 or Garrard 301

Even if the platter replaced with thicker and heavier one those guys always add copper mat on top of it, just like the latest Technics SP-10R.

P.S. @neonknight I am interacting here not with you personally, but with audio subject that can be interesting for others. No matter who is right or wrong, it’s important to add some information and everyone can decide what he like more. "

@chakster 

The above speaks to the concept that I had previously mentioned of the platter being critically damped and non-resonant being a more significant contributor to sound quality than platter mass as a sole indicator. 

I appreciate your above post, its far less combative and judgmental. I hope we can proceed forward on a more civil discourse. 

With any DD that uses any sort of servo feedback to maintain constant speed, the feedback circuit was designed for a particular platter mass.  If you change the platter mass dramatically, it is quite likely you will do bad things for speed constancy.  Likewise if you were to change to a much lighter platter compared to the OEM one.  Now, based on reports of others and my own experiences, there apparently IS some leeway within which some perturbation of platter mass will not do notable harm to speed constancy, but since every manufacturer had a different thought on the feedback loop and how to have it operate, there is no general rule about how far you can go.  I also don't know whether to credit some of the reports one can read on this forum, if you search the archives. Nearly everyone who replaces a 1kg platter mat on a DD with a 5kg platter mat, sometimes more than doubling the total mass of platter plus mat, says how wonderful it is. To me this says more about listener bias than it does about the physics.  And I also don't agree that there is a linear relationship or anything near to it, between platter mass and SQ. Belt drives with 200lb platters do not excite me.

lewm

Nearly everyone who replaces a 1kg platter mat on a DD with a 5kg platter mat, sometimes more than doubling the total mass of platter plus mat, says how wonderful it is. To me this says more about listener bias than it does about the physics.

Why? The physics of the situation are obviously different, so why would you discount that?

I'm really glad to see so much information and ideas being exchanged here.
The point of my post is to get a general understanding of what each drive type might sound like or what people thought it sounds like, so it's good to hear opinions from many different people. I won't be picking just one turntable as I do enjoy having many options. At some point, I will be adding a DD turntable, it should be fun to experience all three drive types in my own system.
I do agree that there are so many different variables in a vinyl setup that contributes to the final sound from the stand it sits on all the way up to the record weight, so deciphering what is contributing to what is almost impossible.

@atmasphere 

Thanks for your thoughts, Ralph. About air bearings, I think that a very heavy platter on an amorphous carbon thrust bushing is virtually immovable - at least, mine is. You need a lot of force to raise it - and more to lower it - 87N per micron, plus the inertia. Compare that to a fragile cantilever. For radial stiffness, see above. The New Way figure is 34N/u.

What you get is a noiseless bearing, and you really can hear bearing noise. I've compared a first class turntable oil bearing with New Way air in a test rig, and it really is no contest. I've demonstrated sleeve bearing noise from a Premotec 1.8W motor through a belt - subtle, but it's there.

Could you please define 'isomeric isolation/mounting'? Is this a journal bearing in an elastic mount? Thanks!