Tables That Feature Bearing Friction

Dear Dertonarm: What do you have in hand? do you already ask you?

You have always a critic against almost any audio item out there ( mainly analog items ) but what you own and design.

You can't prove anything at all with technical or not technical " words "- bla-bla-bla where " even " your TT design is faulty because you detect its compromises years latter.

So where do you think are " seated "?, I know where you are but the mportant issue is if you know it.

You say that in the Verdier design it is a room to improve, well in your whole system design there is too room to improve, but telling this means almost nothing because you can't test/prove it.

There is a " saying ": " of tongue I eat 10kgs. ", facts is the name of the game.
The physics have to applied taking in count its environment, materials, parts, available technology, options, etc, etc where things will happen.

Your position that you already are at the end TT learning curve design goes against your own faulty TT design.

What prevent that when you already make it ( this year ) again " next day " you take in count ( again ) that there are new compromises? that maybe could happen.

You say that the non-technical discussion is futile and maybe some us don't agree with.
I take in count that the common sense and non/technical " debate " is something where you don't have strong arguments, example: like the build materials on a TT design where by physics laws I assume you can predict its precise neutral whole/overall behavior, how? you don't give an explanation yet: is there a precise technical explanation on that subject? or you choose " silence " because you don't have a technical answers?

So, you want to convice that the BD TT " road " is the best and only way to go, better than that: that your design is the best and only way.
There are no valid options even if you don't know it: DD? no, Idler drive? no, other BD designs? no, other options? no: only the one you have in mind and that today you even test it.

IMHO your position leaves all TT designers eating ( with all respect to everyone of them ) in your " hands ".

Well I have a " little " more respect not only for a designer but for the human been they are, just like you.

Regards and enjoy the music.
Raul.

just like you are.

Dear Raul, well we get from you what we got before - loads of technical facts, loads of IMHOs.....

Yes, I can tell you what building materials in what part of the TT are most likely the best to contribute to an excellent behaviour regarding vibration damping and energy transfer.
Why should I tell you. To convince you? Futile attempt from the start.
I guess I have posted enough technical background on the subject in this thread.
A hell of a lot more than you, Teres or Dan_ed together.

But I have learned a lot from you.
Especially one thing: technical facts and physics are sometimes futile in audiophile discussion.

Raul, come on teach us something, come up with some technical explanations why I am wrong and in what aspects.
Show me the way.
And please, technical explanations - not "IMHO"s and not that I shall have respect for others. That I do not bow in awe because of the turntables on the market right now does not mean I disrespect people.

I know that I have stepped on your toes in the tonearm thread and here again.
Sorry.
You are so knowledgeable about these things - why don't you teach us something.
The other TT designers shall just do their homework before telling us that they have found the magic stone.

I did not. All I did is to lay out technical relations and mechnical interactions and that the "complex" turntable does indeed consists of two energy systems.

My other "crime" was that I did insist and still do, that a turntable close to perfection and maybe without compromise can be build.
Somehow this did enerve some people.
As if compromise were a holy cow.
Don't you think that the tonearm you are about to build and to bring to market will be close to perfection ?

Of course in my system is room to improve - maybe as much as in your system.

Dertonarm, thanks for the general suggestion regarding thick & thin, but there are about as many derniers of these synthetic threads as fish in the sea. It would be helpful for this experiment if you could offer a few specific recommendations.

Hi everyone,
I know I will regret posting in response to some of the above, but before I comment on some of what Dertonarm has postulated above repeatedly, allow me to address the original question:

For any given motor/powersupply combination there is a specific load against which it will work producing the least vibration/smoothest rotation. This is, strictly speaking, only true for a motor which has perfect spindle bearings. They are another source of irregular behaviour, particularly since the load on a belt drive motor pulley when used with a thread is rather high(compared to the tension required if a rubber, neoprene, silicone... belt is used). It is possible to address this problem, at the price of complexity and noise(i.e. counter-pulley for the motor spindle...other options exist).

Off course stylus drag isn't capable of slowing down a platter AND at the same time modulating the deceleration(or the acceleration!) at the exact frequencies that are being played back at that moment. The platter acts as a low pass. Nevertheless, stylus drag is NOT constant and therefore requires lost energy to be fed back into the system at an ever changing rate to maintain absolute speed, requiring constant acceleration/deceleration. If the platter is loosing energy due to additional "drag", be it generated by an eddy current brake(no noise added), a felt brake, a paddle running through a silicone bath or a particularly lossy bearing(i.e. the DPS turntable), the influence/impact of the losses generated by the stylus drag become smaller.
Increase the drag tremendeously and you will get the influence of stylus drag below the threshold of audibility(let's just say for a moment that there is such a thing...)*.
You need to increase motor torque(meaning, all other things being equal, increase motor noise) once the losses become too high, both to be able to maintain target speed and to bring the platter up to speed within a reasonable amount of time.
*The same can be achieved by increasing platter mass/inertia, BUT the remaining speed variations will be lower in frequency and higher in amplitude if no means of damping(same as aditional drag, sorry)is employed. Low pitch variations are more obvious/bothersome to some than they are to others.

Since amplitude and frequency of the platter speed variations can't be reduced to Zero, any turntable will be compromised, unless it's platter would feature infinite inertia, in which case all other factors(motor, idler, belt etc.) become obsolete, since nothing can move an infinitely inert structure.

The insistence on the superiority of Dertonarm's super heavy platter driven by a lossy drive/"slipping" thread is hard to understand, particularly if we apply the laws of physics, as continously demand by the master(couldn't resist that one ;-) himself.

If the thread is allowed to slip while it is driving the circumference of the platter, slippage will (likely)occur at the pulley too. Even if the slippage was constant, and it is NOT(according to physics, keyword:"stiction") , slippage on both the driven and the driving surface will result in chaotic behaviour, COMPROMISING the evenness of energy transfer.

If, as some turntable manufacturers have done, the platter speed is monitored and used to control the motor, hunting and pecking is inescapable and only the chosen feedback time constant, the platter mass, the motor torque and the little bit of stretch left even in Aramid or Dyneema threads will govern the speed variation amplitude and frequency around the nominal target speed. And if there is belt/thread slippage or an out of round platter, the "error correction" will have to work very hard.

Dertonarm stated that neither direct drive nor idler drive was usable to build a turntable with high mass/inertia platter. Oh boy... we are mostly listening to shitty records cut on Neumann lathes, some of which use a Technics SP10 MkIII motor(albeit driving a 40kg, large diameter platter)
The Onkyo PX-100M, an eddy current direct drive tt features a 24lbs platter(without the mat) and is an excellent deck.
Other examples in conflict to the above statement were mentioned by Chris Brady.

What does a super heavy platter buy the designer other than inherent higher frequency speed stability? Problems!
You'd be surprised how much wobble/tumble can be detected on platters even if the bearing tolerances are super tight(the Continuum Audio site once had some indepth analysis graphs and animations)
Dertonarm will likely reply that an airbearing is the solution, but it isn't(it's a compromise too). It minimises bearing noise and friction(a major problem with super heavy platters) but can't restrain platter tumble as well as a pressurised oil or grease bearing. For what it's worth, essentially all industrial axial airbearings for heavy loads are made for much higher rpms.

Dertonarm suggests/requests the side load on the platter to be zero. Very good(unless a spindle bearing à la Bill Firebaugh is used)! But if you do this by putting a counterpulley opposite of your driving pulley and maintain not only the distance but also the diameter of the counterpulley, there is a strong risk of all 4 "free" thread sections acting as strings, resonating at the same frequency. Any such behaviour will wreak havoc on the smooth operation of the motor as it changes the load it sees rapidly. Put a break on the counterpulley or change the pulley diameter and the distance accordingly and the problem is solved.
Off course, once the platter is made heavy enough, that becomes neglectable too... depending upon your neglectability threshold.

My conclusion: Dertonarm's way is one way, but not the only way. It is, like all ways, compromised(I wouldn't dare calling it flawed).

A few last words on how "commercial" designers/engineers are often described here and in other forums.
Yes, there are some(too many) that do not have a deep understanding of physics or electronics(not to mention the growing number of copycats). But just as many do and they are into it because they happen to share other people's(be it customers or colleagues) enthusiasm for music and all the gadgets that allow us to enjoy it in it's preserved form. It is simply not true, that all of us think with a target price tag in front of our eyes first. It is simply not true, that all of us think: "yeah, I guess that'll do..." And that is a FACT.

Finally, it is downright ARROGANT to belittle designers who are capable of coming up with a component that delivers 95% of what is currently possible at 10% of the price. Yes, it is all about compromises and ESPECIALLY an all out assault on the state of the art will eventually run into facing this as well.

Happy Easter,
Frank Schröder