Tables That Feature Bearing Friction

From a physics perspective, using the bearing drag to introduce a well defined load for the motor is certainly “sound” as nicely explained by Dougdeacon and others above.

The DPS differs from some of the other tables mentioned above: the bearing friction is significantly higher than on the other implementations since the DPS uses a light platter and doesn't have the benefit of the inertia of some of the above heavy mass tables. The reason behind the high friction is that, in comparison, any friction introduced by the needle (needle drag) is neglible. From my own experience, the DPS is one of the few tables with a light platter that does have any of the associated speed variations and in many ways sounds like a high mass design (of course the base is fairly high-mass anyway as it contains two layers of lead).

I have not noticed any detrimental effects for the DPS, especially not added noise. Several friends have commented that the DPS is in fact easily one of the quietest tables in our group with the blackest background (comparing to TW Raven AC, Platine Verdier, VPI Scoutmaster, Michell Gyro, etc.).

The DPS is IMO one of the most well designed and thought out tables out there. Everything is extremely carefully matched and optimized; e.g. Willi tried several different platter thickness and weight to optimally match the “loading” of the motor. If you are looking for a table with a slightly more compact form factor the DPS should be on your list. On the downside the design is not for someone who likes tweaking - the top base has to be replaced for a tonearm and it already comes with all the isolation and platforms you may ever need.

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