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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
dertonarm
1,042 posts
 
Dear Dan_Ed, agreed on the large scale.
And yes, - there will always be "some" (I hardly can write the word...) "compromise".
However NOT SO FAST.
I do get the impression that most designers are seeking for the nearest possible compromise.
That the real goal for most is: finding the best (read: cheapest and nearest....) compromise as fast as possible.
I have no problem with a compromise when there is NO OTHER CHOICE possible. That is early enough.
And frankly - that point will never be reached in turntable design.
We should get real, we are talking about turntables - not about space shuttles, Formula 1 racing cars, atomic submarines or the hubble telescope.
A turntable - a simple mechanical machine....... sorry, I can not see any need for compromise here. And we do not need back-up by the Pentagon or Northorp Aviation to be able to design and build a near perfect turntable.
dan_ed
2,451 posts
 
Ah, so now we are cutting to the chase.

In the real world, there are always compromises. Even the equations that we use to model real world behavior have compromises built in. One can certainly chose which to address, but on cannot avoid accepting compromise in one way or another. Even if one is not aware of the compromise(s) at the time. That is the leap from paper to reality. EVERY system, mechanical or biological or whatever, in the universe has built in compromises. It is unavoidable. So I propose that we drop the pretense that any system can built without compromises.

I agree that all turntable designers/manufacturers will make decisions based on commercial interests. Absolutely. They want to be able to sell what they have made. However, even those who profess to have spared no expense and made no compromises are deluding themselves, IMO. Look closer, I say to them. Compromises are there.
dertonarm
1,042 posts
 
Dear Dan-Ed, yes, are you happy we arrived in the "real world" (was Neo happy when Morpheus showed it to him...?).
Of course, compromises are there. WHERE they can not be avoided I agree to them. However - I can't stress this often enough: the one basic fault is to make the compromise the goal. And that is what is happening all around and what gives us what we deserve: .... mediocrity or worse.

My point is that the compromise is o.k. when there is no close to ideal (= near perfect ) solution possible.
However - once again and for all - it is NOT nessecary in turntable design.
To accept "compromises" here in the early stadiums we see them in almost all turntables around - those are not compromises.
That is poor, unfinished design.

Named "compromise" just because the designers could not do any better or did not want to go any further (for whatever reason...money , time, market call).

"Unevitable compromises" in a machine as simple and small as a high-end turntable............... really, give me a break - we are in the 21st century not in the dark ages of mechanics following the decline of the roman empire !!!
Its poor performance - not unevitable compromise.
Period.
lewm
13,457 posts
 
Dertonarm, For your consideration, an idler-drive in which the motor force is applied to the underside of the platter, in the vertical plane. Thus no horizontal force needs to be cancelled. No string needs to be chosen or "adjusted". In short, I offer you "Super-Lenco". Take a look at the Saskia turntable. (I know you will dislike the possibility for idler wheel "noise" to be transmitted into the platter, but this is the real world where choices have to be made. Believe me, that turntable is silent.) Put a Saskia on a Minus-K or an industrial isolator for an electron microscope, and you might be in vinyl heaven.
dan_ed
2,451 posts
 
However - once again and for all - it is NOT nessecary in turntable design.

Sorry to use a caloquialism, but I say bullshit! :-)

Since we are on to the drive system in this thread let's use that. For the table that you designed. Did you not find that proper tension on the pulley was critical? Did your math/physics models predict that? How did you find, repeatably, what the correct tension should be?

Let's look at the motor. DC or AC? How about the controller? If you open the doors I bet we can find your compromises. I'm not trying to pick you apart, just your position that no compromise should ever have to be made when building a turntable. The human experience over the last century with building LP playback machines shows otherwise.

Now we can always argue over the compromises that ARE made. That is the sole reason for forums like this.
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