Tables That Feature Bearing Friction


I recently had the opportunity to audition the DPS turntable which, unlike most tables, has a certain amount of friction designed into the bearing. This, when paired with a high quality/high torque motor, is said to allow for greater speed stability--sort of like shifting to a lower gear when driving down a steep hill and allowing the engine to provide some breaking effect and thus greater vehicular stability. I am intrigued by this idea and was wondering what other people thought about this design approach. Are there other tables which use this bearing principal? One concern I have is that by introducing friction you may also be introducing noise. Comments?
dodgealum
Dear Kirkus, there was no way to put that design into a commercial product. Too big (the Caliburn, Goldmund Reference, Micro 8000, Raven etc. were all dwarfs in size), too heavy, too much periphery, your wife would have shoot you and divorce (not sure which first...) upon the sight in teh living room.
And no way for trickling down in more convenient size and financial frame.
Anyway - I will do it once more this summer and autumn and will include a few technical devices which I could not integrate 20 years back. I will post the pictures and specs of the turntable in late autumn here on audiogon.
For all to share.
That implies that the suspension should go as low as 0.5 Hz to ensure isolation from building resonance.
I'm not so sure on this -- after all, at 0.5 Hz the relative stylus-to-record motion *should* be fairly well attenuated simply due to the fact that it's now several octaves below the basic cartridge/tonearm resonance, which is acting as a 12dB/oct high-pass filter.

From emperical evidence, the cartridge/tonearm resonance envelope definately affects the sensitivity of a boingy suspended turntable system to foot-falls and such. So I'm thinking that the primary suspension mechanism of importance is its Q, and flatness through its transition region . . . so it doesn't add any additional peaking to the tonearm/cartridge resonant peak . . . the exact rolloff point for the suspension simply needs to be a bit (an octave should easily do) below the that of the tonearm/cartridge. The best results will then be acheived because the slope of the attenuation (provided by both the suspension and tonearm/cartridge working together) is smoothly increased, without increasing the peaking, and the ultimate attenuation at very-low frequencies could be similar to the system you describe.

Another huge issue is how the suspension behaves with horizontal shock, in addition to its vertical behavior. I think that this is THE main flaw in the Linn/AR suspension, and just about every turntable suspension that uses compression springs. In these systems, since the mass of the subchassis sits above its support points, it's inherently unstable with regard to external horizontal motion. This fits with the long-time Linn recommendation of the Sound Org stand for floorstanding applications . . . something will minimise the addition of horizontal energy, yet cleanly transfers vertical energy to the turntable, where the suspension does its job the best.

Ideally, it seems that the subchassis should be underhung with respect to the fixed chassis, resulting in a stable, predictable horizontal resonance . . . and there's probably some perfect relationship between the horizontal and vertical resonant frequencies that would allow horizontal shock to be converted to vertical spring deflection (through pendulum action).
Well, we do not have to re-invent the wheel here. All this research about suspension has already been done by industry with huge amount of manpower and technical resources. These problems are solved.
We just have to apply them to the turntable system and/or its benchtop / stand platform.
The only problem is: they do not come cheap (as any "good" turntable cannot come cheap....) .......
Have a look at the website of Minus-K and/or Kinetic systems or any of its market competitors.
What will do the work for an electron microscope will do the work for a turntable.
The better of these benchtop platforms will isolate from vertical AND horizontal vibration.
Foot-falls and usual household vibrations from washing machines and in-house motors are not the problem.
The problem is the all-present buliding resonance.
It was an eye-opener for me to actually "see" what isolation from enviromental vibration really means - and what it can do.
If we can agree, that the idealized working conditions are very similar for both turntables and electron microscopes (both "working" in very similar nanocosmos dimensions) - then we already have the solution.
In easy words: you do not have to worry about suspension at all if you put the turntable in question on top of a professional vibration isolation benchtop platform precisely resonance-adjusted to the weight of the turntable in question (and for god's sake - do NOT place any standalone/detached motor-drive on the same platform!).
Borrow one or try to get one from technical scavangers (there are enough companies around selling of the remains from technical-orientated companies getting out-of-business). I bought a good benchtop from Kinetic used via ebay for 1/20th of the list price (o.k. the transport from North Hollywood to central europe was a few bucks too, but not that bad).

Well - a really "good" new isolation platform will cost the same as any of the "avarage" turntables alone.

If the technical aspect and waypath alone are not enough proof, I recommend to all (for once..... to support the technical outline) following Raul's advise: listen to it.
The immediate apparent difference in sound-presentation will tell the story.

As I still am sure that we do work with techincal facts and issues only in the design of a turntable - the turntable "done right" will never come cheap.
If you are into off-shore boats or high-end rifles or high-end motors - no matter where - if you are looking for the "best" in those they won't come cheap either.
You just can't fool around with physics.
In the design of those topics just mentioned - are we dealing with taste or guesswork ? Maybe in the outlook, the cosmetics - but never in the technical design.
In turntable technical design (NOT cosmetics or appearance) its all physics - and honestly, there are moments when I do not like that fact either ........
Thanks for the info, Dertonarm . . . I enjoyed reading about these products.

But it's not a matter of "re-inventing the wheel", its a matter of understanding the exact requirements so as to make sure we understand how well the solution fits the application, and the problems we're trying to solve. Because (to use a silly example), putting your tomato plants in the finest laboratory glassware doesn't mean their fruit will taste any better.

Most of these off-the-shelf devices (i.e. the MK26) appear to have a low-pass characteristic that somewhat resembles a Chebyshev response, which trades some pass-band ripple or peaking for increased performance in the stop-band . . . I'd speculate that this is an excellent trade-off for most of the laboratory applications for which they're sold. But for a turntable, the low-frequency peaking of these products may indeed cause some problems. I'm sure they still sound excellent . . .

. . . but if you truly want to do a turntable "right" as you say, then simply sticking i.e. an RX5000 on an off-the-shelf Minus-K platform doesn't cut in my book. Using existing laboratory-instrument technology might be a good approach . . . but if you want the BEST performance like you say . . . a custom-designed product that had its stopband/passband performance tailored specifically to a turntable application is what you should be after.
Dear Kirkus, - well a Micro RX-5000 on a (specified for the Micro 5000's weight load) Minus-K is already a different beast.
The one vital point is, to really use a platform only, which is specified for the exact weight of the turntable in question.
One problem is however, that all the benchtop isolators do only perform their best with fairly heavy load (at least heavy for a turntable...).
As the better ones are designed to work with fairly big (= heavy = expensive...) microscopes and similar costly technical measurement equipment (= the users have little limit on spending extra to get their instruments show their best....... as always - they are all "in it for the money"...).
However your proposal to carefully tailor laboratory-instrument technology hits the point. It is exactly what I am doing in my spare time the past 2 months.