Tables That Feature Bearing Friction

Please explain why pulley material would be audible when used with a 70 lbs. platter. I don't have a clue what physics are involved for this case.

Well, assuming that this is a thread-drive system with "controlled slippage", and assuming that you're talking about the motor pulley . . . . the first thing to look at would be the effect of the pulley material on the coefficient of friction on the belt material, both in terms of the material itself, and the resulting surface finish from a given machining process. Second, looking at some pulley designs (again using the Micro RY-5000 for reference) I'd guess that it *could* exhibit different resonant characteristics when made of different materials. And of course, if changing the pulley material changes its mass . . .

But the effects of these criteria are going to be highly dependent on the actual vibrational energy coming from the motor in the first place. And when they reach the platter . . . just because it weighs 70 lbs doesn't mean that it doesn't resonate, and that vibrational energy can't move through it.

And yes, this is all speculation . . . but from speculation comes hypothesis (not theory) . . . which is generally the first step in good science. As Raul pointed out, it's not that basic Newtonian physics doesn't apply, it's just a matter of having the time, money, and common sense to find out how.

While testing different belt materials (DIY belts) I was quite amazed at the variety of achievable effects it had on the sound reproduction and impact this part of turntable setup had on sound. The differences are obvious and no golden ear required to hear that phenomenon. However, I would not stress the issue of why or what gives - you can not measure passion for music, can you? If the formula works, great. If it works in the ears of many, that is truly, truly magical. Why, because we are this funny group of people that tends to criticize music for locking musicality. To bad we stress and debate over silly rather then just listen. I am sure we all have an opinion of what others should buy or listen. Well, maybe it is time to reevaluate our own so call "reference" and get off the high horse. I've heard my share of so called "reference" setups by individuals which know it all.
I am still dizzy.

I agree with Teres - there is more to it then theory.

.....and enjoy the music

Mariusz

Dear Mrjstark, dear Teres, if there is more then theory, then we are either in mysticque or religious grounds.
Different belts having different (negative and positive) effects on the bearing an dteh rotating mass system and on the transmission of vibrations is certainly no mystery nor unexplained by sience.

Dear Lewm, a no force belt/thread/string driven bearing is done this way: picture the motor left of the platter. On the right side - same distance as the motor to the bearing - is a 2nd spindle (or easier: motor without active force) which mirrors the position of the drive motor. Here the belt/thread/string finds a 2nd pulley equal to the one on the motor. The spindle of this "counter device" should be same as teh motor sindle and all its moving parts shall be equal dimension and material.
Correctly done, there is now no resulting force anymore on the bearing in horizontal / lateral plane/dimension. The force of driving has 2 equal vectors now which do give which do zero each other regarding their effect on the bearing as they do go in opposite directions.

Dear Kirkus, the "controlled slippage" is tricky to set-up, but if used with the "right" (= close to zero elasticity) thread it is very durable and does not request to be re-adjusted.

The drive-system is - as always - a matter of quality in the selected parts. I still do favour using any of the big Studer 800 capstan motors as drive motor for a "good" turntable. These capstans are expensive -yes. They require some pretty expensive periphery too - yes. But they are a totally different league.
These capstans are at work since the 1960ies in almost all great recording studios and a majority of all music recorded between the late 1960ies and early 1980ies (and beyond...) were recorded with these capstans being a direct and very paramount part of the big tape recorders.
Use one of these and give it the regulator circuit is needs and 98% of all problems with other motors and drives are vanished. Motor-born vibrations are minimized too.
And yes - it will cost you about $2000 alone in parts.
Quality NEVER comes cheap.

As for the clamping platter record interface. I do have the solution for that problem at hand. It however is rather expensive and labour intensive again. I do not think it makes sense to unfold it here.
The discussion about again too expensive and not suitable for a commercial product and crompromise etc. will just go on and on.