Tables That Feature Bearing Friction

Fascinating stuff . . . great thread (pun intended).

I will admit that I'm having a conceptual problem with the whole "controlled slippage" approach to filtering the motor vibrations from the platter. I can see how it would work brilliantly if all the conditions were carefully balanced . . . it just seems really inconsistent in terms of day-to-day usage, and likely to require very frequent tune-ups at least in terms the thread tension. But I will admit that I am comparatively ignorant of the real-world characteristics of these actual materials in this application.

Just a couple thoughts on the drive-system subject - first, how much data is available on the characteristics of the rotational vibration produced by the motors themselves? It seems to me that the relative strength and spectrum of this energy would be of paramount importance to determining the amount of slippage, the tensile flexibility of the belt or thread, and the necessary mass of the platter (and inertial flywheel device). Second, there is actually one more slippage mechanism -- that between the rotating magnetic force vector produced by the motor's stator, and the speed of the armature. It would seem that it's the interaction of these two time constants (or three if there's an inertial flywheel thingey) that ultimately determine how effective the motor/platter isolation can be.

Also, Dertonarm brings up the point of clamping and the record/platter interface, and I agree that it's undeniable that the platter must be of sufficient mass to effectively sink the vibrational energy of the record. But as far as the proper way to make the record-platter interface, that's another issue. There seem to be obvious drawbacks with clamping (tolerances in record dimensions, flexibilty, and condition), vacuum hold-down (complexity, noise and reverse-side dirt-bonding), and mere gravity (poor coupling). I confess that I don't really have an opinion as to what the "ultimate" solution has to be . . . maybe we just play lacquers! Issue solved! :)

*** Well - the physical phenomenons regarding the turntable CAN and ARE fully understood. Unfortunately and apparently not by the majority of turntable designers. ***

Some of the phenomenons are well understood but many are not. 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. I also am quite doubtful that even with the best equipment that this effect could be measured. I am not suggesting that this is magic. Something logical and scientific is going on, I just don't know what it is. I am sure that plenty of folks can come up with theories about why, but theories are not that same as really understanding the physics.

Oh, and yes this is a real effect that many folks have heard. Please lets not get into the subjective vs objective debates...

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.