Tables That Feature Bearing Friction

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.

In general we shoul decide, whether the main subject is how to design a turntable as a commercial product, or how to design a turntable which tries to reach the limits of playback possibilities.

I must admit that it is rather depressing for me to read in these posts so frequently that "this gets too expensive"....."have to made trade-offs".........."well-choosen compromise"........ "bring to market"........"commercial product".

This all sounds like the usual political paraphrases.

As was mentioned before - if we do not demand and strive for the best possible (an audio industry will tell us it is the "best possible" anyway every 4-6 months...) - we will only get what we have got so far:

......mediocrity.........

Time to add something to the physics discussion here:

if there is more then theory, then we are either in mysticque or religious grounds.

I would like to clarify this a little more since there is a lot of confusion on words, especially on the terms physics and theory. There are several reasons that a theoretical prediction doesn't agree with praxis (and none of the reason invalidates the theory or physics in general). Without going into too much technical detail:

- First of all physics does capture everything in the world and the physical laws certainly apply completely to turntable design or to the electrical processing of the signal for that matter.

- The real problem is, we are dealing with complex systems: Yes, Newton'sche Mechanic describes the basic mechanical motional aspects of a turntable completely. And things like vibration transfer in the platter, tonearm, etc. are covered by solid-state physics. However, most of the equations one ends up with when describing a system completely is far to complex to be simulated on a computer.

- For example, we could describe every microscopic particle and its motion in the turntable; the problem is there are more than 10^25 particles in a turntable; i.e. 10^25 coupled nonlinear equations. With our standard computers we would have to wait a few thousand years for the computation to finish.

- Thus certain approximations and assumptions are generally applied which simplify the equations and make it possible to calculate the system behavior. Most of the times this gives a good enough "picture" of the system behavior, but quite often calculations and predictions do not capture every detail and minor aspect ton include these details we would have to revisit our assumption, include less approximations and more terms in our description which in turn makes things complicated to calculate and predict again.

- As a result, practical trial and error is often a lot easier which is why some (like Teres and Mjstark) would probably refer to turntable design as “art rather than science”. Now, basic simplified engineering equations may not describe the results of our excellent practical outcomes, but the underlying physics is still accurate, but just too complex for a full calculation and prediction.

- A lot of the things we are talking about here (belt creep or slippage, effect of different belts, different pulleys, stylus drag, etc.) are higher order corrections that are difficult to model, but easy to try out in praxis. Even the Apollo missions rely on practical trial and error in the development stage as well as practical tests in addition to basic physical principles.

- Finally, some semantics: There is a subtle distinction between the terms "Theory" and "Hypothesis".The terms are often used interchangeably which is incorrect. Scientifically there is a big difference (see for example the Wiki)

- Just because a system is complex and difficult to predict it does not necessitate religion or mysticism. Similarly, just because we don't measure an effect, but we hear a difference doesn't mean the physics is wrong; it just means our approximations and theoretical assumptions are wrong and/or we measured the wrong things.

Bottomline, we could probably achieve a lot more with a careful scientific description of turntable design (as Dertonarm instigates), the whole audio system, and even human hearing. But in praxis, trial and error and careful listening is still a lot easier and effective in achieving better results (which strengthens Teres’ point).

This is just the perspective of a physicist of course ;)

Rene

Dear Restock, a superb post - thank you very much! I would like to mention however that I do not see me in some kind of opposition regarding Teres, Raul or any other of the well-respected contributors to this thread.
I just wanted to clarify the point that this particular part of the audio chain is - besides the tonearm... - the most simple to handle. Here we do only have to work with mechanics. The other components are either electrical or machanic-electrical transducers (much more complex ). Taste, personal preferences and opinion, room interaction and matching impedances and many more do have enough room in the development ofspeakers, cartridges and amplifiers. and they are NEEDED there.
But not in TT design.
Yes, -in the end everything in music in subjective.
But the very best turntable possible will have absolutely no sound signature of itself. It will just allow the maximum in clear detailed information to be extracted from ANY given cartridge/tonearm combination.
The turntable is nothing more than the enviroment, the basic floor on which the analog-playback starts.

But if we relay on hearing/listening in turntable conception and design, we automatically imply that the turntable is the weakest part already and per se in the particular audio-system used to determine its quality.

We all see the problem: to judge the performance of a turntable design by sonic performance, we would need an audio-system were all the other parts are "better" than the TT under question.
But most likely we will design a turntable which "sonic signature" will mask certain flaws of the audio chain used to develop the TT.
It will be designed to compensate flaws of the evaluation system used to develop it.
This dilemma is omnipresent in audio of course. However in the turntable we have for once the opportunity to design on pure physical, mechanical parameters and facts.
I do see a clear and straight road here.
It may be long road and the journey may take a lot of effort in many ways.
But the goal is that mountain clearly visible in the distance - not the next inn or diner which will lure us with comfort (=compromise) by the first signs of effort or weariness.
Once entering the door of that inn and sit down at the table you will not carry on on that journey. The day is done and teh job as well. You went awhile and has reached new ground. Its o.k.
Thats what happens all too often.
We should be strong enough to walk through the night.
We should not discard the opportunity to reach the mountains that easy.
As is so pathetic written on the memorial for the american pioneers (hope I remember is right... in brackets are my synonyms....):

"the cowards didn't start (CD-player from Radioshack....), the weak died on the way (settle happily with current "state of the art products".....) only the strongest reached the mountains - they were the pioneers (.....and probably died exhausted, wounded and torn by life - but o.k., if they did what they wanted and reached what they dreamed of)".

Well, sounds like a pathetic political speech for fortify indurance in the sight of worldwide financial crisis doesn't it ??

Did I mention this is about turntable design....?

I think one can some up the problems very simply, but I'm probably just restating what has already been posted here. As I see it the problem is not of design and proper application of physics. The real, true problem is integration. This is true of any complex system, not just with turntables.

You can design and plot and plan all you want. There will still be some compromise or component that you have to go to the shelf for. And then you are constrained by the operation of that component. That is when "feel" takes over, right or wrong. This is true for any complex system in the real world. This is the realm of practical experience and personal preference. This is also the realm of great breakthroughs and great failures.