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. |
Of course there are motors capable to drive 100 lbs platters by direct drive or idler. But not with excellent results - at least not compared to what is possible.
Credible arguments for a light and responsive platter.....??
Very interesting - give me one (aside from being cheap and easy to handle for the motor). |
Dear Dgarretson, if you want more grip you may need a slightly thicker thread. If you want less grip make it thin. The knot itself - there is no secrect. Just make sure to make a knot which is on one side only. Yes - that way the knot will wander to the outside. This will take some revolutions, but after a while the knot is constantly on the outside of the thread and does not longer bounce against the spindle or platter. You may use any aramid or dyneema on the market. They are cheap and are available in different colors for low $. |
Dear Jloveys, teh Verdier Magnum has some very interesting points. The oil pressure bearing is an extremely good solution for a bearing which is both - able to handle very high platter weight AND provides a very low friction and extremely high damping. Very good. The platter features super high inertia (the large diameter...) but would even be better with an internal damping or a compound (3-5 cm metacrylat or vinyl on top of the platter and at the underside too. thus the platter would be dead quiet and teh vinyl record would see a contact surface with identical density - which is optimal). I see some room for mprovement in the suspension and in a possible counterspindle to make the bearing vector/force free. But it sure is a serious machine with several very strong points and going in the right direction - super high inertia, super high mass in motion ....... |
###
- possible highest platter weight
- possible to use high inertia for self-stabilized speed
At least the last two reasons can not be used with idler or dd drives. ###
Wow you are dead wrong about this. The Rockport Sirius is direct drive and uses a 62 lbs. platter. The Certus DD turntable uses a 60 - 75 lbs platter. The Verus rim drive motor has been used (with excellent results) with platters up to 70 lbs. There is no reason practical or otherwise that limits direct or idler motors to light weight platters. The Certus motor is more than capable of driving a platter well in excess of 100 lbs.
BTW: we have done direct comparisons using the exact same 75 lbs. platter with belt and direct and rim drive. They all sounded considerably different and the belt drive was the clear loser.
Your heavy platter, slipping string design is one of many possible approaches to turntable design. But
- it is not the only correct way
- it is not the only concept that "agrees with physics"
- it is not an idea that cannot be improved on
- it is not without compromise
- in my experience the slipping string part of the design
is inferior
- the heavy platter part I agree with, but others can make
credible arguments for a light and responsive platter.
I have have no problem with disagreement. In fact it can be a lot of fun and enlightening. But the constant demeaning of dissenting opinions has gotten old. I am done... |
Well Dan_Ed, you might see it as a complex system. It is to some extend - as I have mentioned before. But not all that bad.
Flame war ? No, I am after results - not opinions.
But it seems very hard to get the message out. |
Dertonarm,
The complex system I have been referring to IS the turntable. I don't believe you are really this thick-headed. I believe you are just looking for a flame war. Try AudioAsylum, they love that stuff over there.
|
Dertonarm, before you go, what specific test/thickness of aramid or dyneema do you recommend, and what type of knot do you use? I have something like the no-force platter bearing & thread drive sytem you describe(though achieved by means other than dual motors) and would like to try your threads.
|
Have you seen/heard the new Platine Verdier Magnum with 135 pounds 50 cm diamater massive platter levitated by hydraulic oil suspension inverted bearing ?
A work of art to say the least ! |
Can we return to a discussion about technical issues on turntables......
Do someone have some technical input to give.
Otherwise I will rather continue watching FC Barcelona destroy FC Bayern München (which by the way - is today a display of applied superior technique and cool intelligence (but displayed with a burning heart!!) over ignorance, arrogance and selfsatisfaction (football not turntable design....) - go Barca !!!!
Switch on the TV - much more entertaining than this thread by now. |
No, I think that not you but maybe some of us ( I'm in. ) are so stupid.
Sorry to disturb you. You are the man, you know?
Raul. |
Dear Dan-Ed, the turntable stands alone............. alone......... it does not have to be integrated into the audio-system. It does not depend on any other part of the audio chain.
There is no language barrier.
I find it funny that several other posters by now are doing nothing else in their posts than trying to persuade me that my "no compromise" is wrong and futile.
What do you want?
Do you want me - with the words of Lyndon B. Johnson - "rather inside the tent peeing out, then outside the tent peeing in" ?
How about giving the thread some technical input?
I guess I did.
Come on - show me why we are doing and need this and that compromise in turntable design.
Show me technical facts or at least some nice theories why we shall use idler drive or direct drive.
Just telling me that this or that turntable will give me sonic (vinyl) heaven is just not enough.
I am not dogmatic - if there are good technical reason to use other paths - display them here, I will be the first to walk them (I if haven't already).
If someone feels personally attacked because he do own a turntable which maybe have features I have critized or abandoned in my posts- sorry, this is in no way personal.
All I hear are opinions and many comments that I shall give in and accept the need for compromise.
Great.
I thought this is about turntable design and technical issues.
Is there anybody out there who could come to my alliance and bring us back on the track ?
Am I just too stupid or is my english too poor to realize?
Or both...... |
|
Dear Dertonarm: I forgot, this thread " discussion " IMHO is only that a discussion not a contest ( technical or not. ) with a winner (s) and defeat people and IMHO too no one ( including you ) can say that in a subject ( like the TT BD design. ) " he " finaly achieve the end top " position " on the learning cuve of that subject.
You point out somewhere: only the " mother nature " make no mistakes, I'm sure and have no single doubt that you are not the " mother's nature ".
I applaud your attitude in your " believes " ( I think that you don't have be on the defensive. ) but that is: your " believes " ( that I respect and that I agree in some ways and issues. ) not other " believes ", maybe today other people ( including me ) can agree on some of your " believes ". I thank you to share it in this forum.
Regards and enjoy the music.
Raul. |
Dear Lewm, I certainly do not want to get into an argument about idler, dd or belt drive. Yes, I agree - everyone has his opinion. And I do not have any problem with other opinion. But I still see this as not about personal opinions but technical principles.
So please do not take the following lines personally, but just as a technical statement.
Believe me - if there would be a direct drive suitable for a really good turntable, I would have used it.
And I still do have access to every possible drive mechanismen and motor in the very highest possible quality. There is no direct drive suitable to rotate a 100 lbs platter with close to zero vibrations and good constant speed - the problem to begin with is the inertia. The high inertia will get into a conflict with the direct coupled motor - same in idler drive. Both drive mechanism do imply total control of the speed by the motor itself via direct coupling.
Thus why all DD platters are fairly lightweight. The DD gets huge problems with high inertia. In any DD inertia is contraproductive. Let me just briefly explain, that there are at least 3 paramount reasons for using a belt drive for a turntable:
- possible lowest vibration transmitted to turntable by thread
- possible highest platter weight
- possible to use high inertia for self-stabilized speed
At least the last two reasons can not be used with idler or dd drives.
Thats why I can not take those two drives into serious consideration.
I know that I do need a super high mass platter which is acoustic dead to reach best possible performance. This should be obvious from the technical facts displayed earlier in this thread.
The idler drive was well explored and professionell researched by EMT and others in the 1950ies and 1960ies.
I guess we all would agree that one of the best possible ways imagined to drive a turntable would be to apply a constant stream of air (without frequency pulse of course.... BTW - thats a drive mechanism I currently am musing about). The next closest approach to that ideal would be the 'en tangent' thread drive with force free lateral bearing.
However - every technican into dynamics and machines will tell you that high inertia will undoubtly provide the most constant speed possible. Why working against a natural force if it gives you a huge advantage for free?
With both idler and DD you have very direct coupling (with a hunchback of problems....) and the speed is direct related to the motor.
Well, I am really sorry, but it is technically and physically obvious that this is not a good idea......
You may use a turntable with a direct drive or an idler and may be very happy with the sonic results.
Thats fine with me.
And it is your opinion which I respect.
Just respect that I would never use either drive and that I KNOW (physically, technically and from experience) why I do not. |
Maybe we have a language barrier. I AM talking strictly facts. It is a technical fact that in order to integrate ANY system, compromises must be made. Insist all you want. You did make compromises throughout the process of designing your table. You have documented them here.
As I suspected, this discussion is moving into the realm of dogma. |
Sorry: think and live at the last sentences instead of " thing " and " leave " .
Raul. |
Dear Dertonarm: I agree in almost all the " main " subjects about TT's BD design.
Yes, it is a very very simple item ( not a rocket to Andromeda. ) to design, almost everything is physics laws aplication with common sense.
Yes ( like any other link in the audio chain ) it must be dead neutral/accurate ( not confuse with analytical, cool, etc, etc )no doubt about. Its job is simple: to run with accuracy/stability at 33/45/78 rpm adding nothing and degrading nothing, a " perfect target " where there are no compromises.
Sounds easy and beautiful!!!
But ( I hate the " but's , but exist. ) how the " science " can predict for example: which material build ( or a blend of materials ) is the right one for the plynth? for the platter? , for the arm board? for the bearing?; which is the " behavior " ( how are its resonances, time of energy dissipation, distortions/colorations. Its behavior is exactly the same at 33rpm than at 78? and a lot of questions that we have to give a precise answer in scientific way and in subjective one too. ) of those build materials when we run the TT along any tonearm with any cartridge? : what kind of distortion/coloration the cartridge is taking from the TT it self? from where comes those " distortions "? exist the " perfect " material? where? why? and I can go on and on.
In a perfect/ideal design we have to have precise answers to many questions and the way to " solve " the " stones " in the road.
Years after you made your TT still have " questions " that you will try to " answer " this year.
Why the physics laws can't help you given to you the right answers when you made the design? maybe because you are not " perfect "? maybe because there are other " roads " to go? maybe? maybe?......?
Like I say in my first post about: IMHO your approach it is not the " only and the best " it is the approach of how you " see " and how you " answer " to the TT design.
I already " see " which one is/was your " answer " to other audio items in your system ( No this not to start a different debate. So, please stay calm about. ) and IMHO not a " perfect " ones. Maybe for you are perfect ( and this is the important subject because you are the one that must live and enjoy any single day. ) but the WORLD is a little more wide than each one of us.
I like this thread where any one of us ( one way or the other for the good or bad. ) are learning many important things that could make that each one of us make a " revision " of our audio/music targets/priorities and what in reality we are hearing in our each one home system: " perfection " or real mediocity or...or...?
Many of us are satisfied with our home system that is full of distortions/colorations ( it does not matters prices or item names ) and IMHO we must grow-up: if the designers, reviewers and audio dealers don't want it or can't it at least we must ask/cry out for it.
Now Dertonarm, sooner or latter we have to put our foots in earth, we have to thing that we don't leave in an aisle way but surrounded by a very wide/different environments and in many cases we can't take out its " influence " ( any kind. )
Regards and enjoy the music.
Raul. |
Dertonarm, You are entitled to your opinion, but please acknowledge that you DO have an opinion - that the ultimate turntable must have a humongous platter driven by a string or thread. That is an agenda in itself. You have closed your mind to other ideas, no matter how well executed. We are just beginning to see how good idler-and direct-drive tables can become, in my opinion and assuming the vinyl renaissance continues for a whle. After all, belt-driven tts have been researched almost exclusively since at least the early 80s, whereas these other technologies were all but abandoned at that time. Anyway, thanks for all your insights; I do not mean to be argumentative. By the way, I would guess that a "cheap" idler- or especially a direct-drive tt costs more to make than a "cheap" belt-drive tt, which is a part of the reason those drives were abandoned. |
Dear Mrjstark, indeed - many music critics who never played an instrument and many TT designers who never understood what they are doing.
If we already have so many weak links why adding another.......
But this will lead us nowhere.
I have my points of view - others have their.
Anyone out there who would like to discuss any other technical topic of the complex turntable ? |
Dear Lewm, well my comment about an idler drive in turntable design today should be clear.
Not really curing one problem ( draw a force vector diagram and give it a deep thought - the bearing of an idler drive (motor force applied to the underside of platter at one point or to the rim of platter at one point) - as it is done so far - is NOT free of horizontal force.... ) and by doing so creating a few others (not just noise...) seems not a good idea.
This is a drive concept of a time long gone by and for a purpose which has nothing to do with quality, but which only applied to broadcast services and disc-jockeys and which is pretty inexpensive to realize. Broadcast stations worldwide discontinued the use of idler drive TTs over 30 years ago. This should tell the story. Furthermore I already said before, that I will never give any comment about any commercial product currently on the market.
As for Vinyl heaven............. I can see paradise, but there is no light.... |
It would be harsh to own this perfection in the system of so many weak links.
-------------------------------------------------------------
We already have music critics who never played an instrument - and now this... |
One afterthought: when I mentioned that none of the compromises in my earlier design were detected and weren't detected either by other designers in their design this was NOT ment to be understood as me being a "better" designer. Not so.
I am not a designer at all.
My approach is common sense and clear view, clear focus on the point.
This and as Van Morrison said: no method, no guru, no teacher.
And my design was back then - as will be the new one - NOT a commercial product at all. So all inevitable compromises regarding a commercial product can be spared anyway. |
Dear Dan_Ed, I can't offer the eloquence displayed in your opening sentence of the last post, however I will once and for last try to clarify my point:
Compromises where they are inevitable.
As for the questions asked:
- no, string tension was not that critical - it just prolonged the time frame to full speed.
- yes, it was no problem to find repeatably the right tension. I had a calibrated spring gauge and a laser to determine it.
- DC and / or AC - as I wished. The controller was the control board from the Studer fortified with a custom build amplifier to create the signal.
There were compromises in my early design too. Some I did only detect years later.
None that were detected by others. None that others detected in their designs ever.
Thats why I am doing it again this summer and autumn.
But even if I go on and on with the details it will not cure the problem.
Me insiting on the "no need" for compromise in turntable design seems to be a kind of sacrilege to some.
The human experience shows us that it took almost 8 Millenias of civilisation till democracy took over on a larger scale.
Does this proof anything??
One century of turntable design. Maybe. But only the last 30 years did came up any turntables trying to be "state of the art". So its pretty young an evolution. Shall we give up now? Seems as if quite some people would prefer things to stay the way they are.....
Sorry, - somehow I am missing the point........
I would much more prefer to return to technical facts and hypothesis then debatting about my unability to realize that inevitable need for compromise.
There must be something extremely tempting and attractive about finding early compromises and life in peace with them ever after.
I am sure I am just too simple minded to see and realize that attractivity.
Poor me. |
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. |
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. |
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. |
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. |
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. |
Dear Mrjstark, if you ever should try different belt materials on a force free lateral (horizontal) bearing, you will observe that the noteable differences in sound will be much less compared with the differences noted in the "standard" (=one motor - no counter spindle) set-up.
Why do we hear so huge difference (I will certainly not deny the fact that there are audible differences with various belt / thread materials and other tweaks in turntable design (mats, clamps, isolator feets, spikes, platforms etc.)) even in state of the art turntables ??
Because these turntables are NOT finished "products" (seen in the sense of a market or as a non-commercial design).
Most likely the designers were under time-pressure and/or seeing the end of the budget and thus need to bring the TT "on the market now".
A "finished" turntable (or any other really "finished" product....) will either show no positive differences with various tweaks or they aren't possible at all due to a design which takes all aspects into count and leave no room for our "add-on", "upgrade" or "tweak"-mentality.
You can't tweak a turntable with force-free bearing running with an aramide or dyneema thread. There is no better material possible so far.
You can't tweak a Minus-K 0.5 Hz suspension by putting spikes or cones underneath. It is already suspended in the best possible way.
We do hear so many differences with so little changes in so small parts because the turntable is so weak.
Because there is so much room for further improvement.
Because we stop too soon.
Because we are satisfied with so little. |
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. |
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....? |
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 |
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......... |
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. |
Dear Lewm, a no force belt/thread/string driven bearing is done this way: picture the motor left of the platter. On the right side - same distance as the motor to the bearing - is a 2nd spindle (or easier: motor without active force) which mirrors the position of the drive motor. Here the belt/thread/string finds a 2nd pulley equal to the one on the motor. The spindle of this "counter device" should be same as teh motor sindle and all its moving parts shall be equal dimension and material.
Correctly done, there is now no resulting force anymore on the bearing in horizontal / lateral plane/dimension. The force of driving has 2 equal vectors now which do give which do zero each other regarding their effect on the bearing as they do go in opposite directions. |
Dear Mrjstark, dear Teres, if there is more then theory, then we are either in mysticque or religious grounds.
Different belts having different (negative and positive) effects on the bearing an dteh rotating mass system and on the transmission of vibrations is certainly no mystery nor unexplained by sience. |
While testing different belt materials (DIY belts) I was quite amazed at the variety of achievable effects it had on the sound reproduction and impact this part of turntable setup had on sound. The differences are obvious and no golden ear required to hear that phenomenon. However, I would not stress the issue of why or what gives - you can not measure passion for music, can you? If the formula works, great. If it works in the ears of many, that is truly, truly magical. Why, because we are this funny group of people that tends to criticize music for locking musicality. To bad we stress and debate over silly rather then just listen. I am sure we all have an opinion of what others should buy or listen. Well, maybe it is time to reevaluate our own so call "reference" and get off the high horse. I've heard my share of so called "reference" setups by individuals which know it all.
I am still dizzy.
I agree with Teres - there is more to it then theory.
.....and enjoy the music
Mariusz |
Please explain why pulley material would be audible when used with a 70 lbs. platter. I don't have a clue what physics are involved for this case. Well, assuming that this is a thread-drive system with "controlled slippage", and assuming that you're talking about the motor pulley . . . . the first thing to look at would be the effect of the pulley material on the coefficient of friction on the belt material, both in terms of the material itself, and the resulting surface finish from a given machining process. Second, looking at some pulley designs (again using the Micro RY-5000 for reference) I'd guess that it *could* exhibit different resonant characteristics when made of different materials. And of course, if changing the pulley material changes its mass . . . But the effects of these criteria are going to be highly dependent on the actual vibrational energy coming from the motor in the first place. And when they reach the platter . . . just because it weighs 70 lbs doesn't mean that it doesn't resonate, and that vibrational energy can't move through it. And yes, this is all speculation . . . but from speculation comes hypothesis (not theory) . . . which is generally the first step in good science. As Raul pointed out, it's not that basic Newtonian physics doesn't apply, it's just a matter of having the time, money, and common sense to find out how. |
*** Well - the physical phenomenons regarding the turntable CAN and ARE fully understood. Unfortunately and apparently not by the majority of turntable designers. ***
Some of the phenomenons are well understood but many are not. Please explain why pulley material would be audible when used with a 70 lbs. platter. I don't have a clue what physics are involved for this case. I also am quite doubtful that even with the best equipment that this effect could be measured. I am not suggesting that this is magic. Something logical and scientific is going on, I just don't know what it is. I am sure that plenty of folks can come up with theories about why, but theories are not that same as really understanding the physics.
Oh, and yes this is a real effect that many folks have heard. Please lets not get into the subjective vs objective debates... |
Fascinating stuff . . . great thread (pun intended).
I will admit that I'm having a conceptual problem with the whole "controlled slippage" approach to filtering the motor vibrations from the platter. I can see how it would work brilliantly if all the conditions were carefully balanced . . . it just seems really inconsistent in terms of day-to-day usage, and likely to require very frequent tune-ups at least in terms the thread tension. But I will admit that I am comparatively ignorant of the real-world characteristics of these actual materials in this application.
Just a couple thoughts on the drive-system subject - first, how much data is available on the characteristics of the rotational vibration produced by the motors themselves? It seems to me that the relative strength and spectrum of this energy would be of paramount importance to determining the amount of slippage, the tensile flexibility of the belt or thread, and the necessary mass of the platter (and inertial flywheel device). Second, there is actually one more slippage mechanism -- that between the rotating magnetic force vector produced by the motor's stator, and the speed of the armature. It would seem that it's the interaction of these two time constants (or three if there's an inertial flywheel thingey) that ultimately determine how effective the motor/platter isolation can be.
Also, Dertonarm brings up the point of clamping and the record/platter interface, and I agree that it's undeniable that the platter must be of sufficient mass to effectively sink the vibrational energy of the record. But as far as the proper way to make the record-platter interface, that's another issue. There seem to be obvious drawbacks with clamping (tolerances in record dimensions, flexibilty, and condition), vacuum hold-down (complexity, noise and reverse-side dirt-bonding), and mere gravity (poor coupling). I confess that I don't really have an opinion as to what the "ultimate" solution has to be . . . maybe we just play lacquers! Issue solved! :) |
Yep, expensive is the hated word for the day. Expensive applies to both commercial and one off, all out assaults. It's just that the threshold for a one off can be much higher. Maybe a solid gold platter would sound really good...
For me expensive mostly relates to time. There are a lot of ideas that have merit. But it is not possible to experiment with all of them. I am sure that I have discarded some good ideas because I didn't have enough time. Part of the art of design is guessing the most profitable ideas to explore. Nobody gets them all right, but one of the important skills in this endeavor is the intuition to get it right more often than not. |
Dertonarm, You have written that there should be no force on the bearing in the horizontal plane, and elsewhere you have written that use of more than a single motor is a no-no. (I agree in both cases.) But how would you achieve the former goal in view of the latter principle? |
There are some good ideas: BUT super high quality motor - the Designer has to know this part - he has to know how to use it - he knows, it makes his product more expensive excellent power-supply - see above really heavy platter - the Designer has to know: this alone is not enough - he has to know how to use it - he knows, it makes his product more expensive superb bearing - too expensive superb drive counterpoint - well, you know now: expensive What is the most hated word today? I think: expensive The customer would probably pay the price, but he pays it also, when a "Test review" is great (whatever this means) or when his wife says "Great, I like it" Most don't need more. Or? A real audiophile lives in pain or is Single :) |
Dear Teres, dear Raul, I guess we all agree in most aspects regarding the main topics / issues of designing a turntable.
I just have a very different threshold for "compromise". However I would like to answer Teres's 4 points first and in order.
I will speak very frankly here, as I just do not want to waste time and words.
1) Well - the physical phenomenons regarding the turntable CAN and ARE fully understood. Unfortunately and apparently not by the majority of turntable designers.
This is NOT all that difficult.
Unfortunately there are a lot of ill-founded theories and nice opinions around - right, but there are also the facts.
It is a fairly simple model consisting of two parts linked in one moving mass.
We have a rotating mass (the platter), that has to been kept on constant speed. The speed vector is provided by an external source (the motor ....whatever motor) the imperfections of that source (vibrations, unconstant speed) shall not be transmitted to the moving mass. This is one part of the whole system.
The second part is the act of extracting the musical information from the record groove. This act is a long line of different (both in amplitude and frequency) mechanical impulses transmitted into the record and into the rotating platter (the moving mass in motion = part one of the whole system). These mechanical impulses (which are a direct by-product of the stylus extracting the information from the modulated groove) depend on the VTF and the compliance of the cantilever (a FR-7 with low compliance and 2.6 gr VTF will transmit much more energy into the vinyl compared to a Shure V15 mk5 or similar (to name two extremes) while running through the groove and de-modulating the engraved information).
However the moving mass - the rotating platter - is therefor "threadened" by mechnaical vibrations from 2 different sources and (maybe - if anything like direct coupled) variation in speed from its external source of speed.
How to solve problem no. 1 (source of speed = motor) was discussed by me the last 2 days and is so far the only suitable solution if you want to use a motor (or multiple which is NOT a good idea...) at all.
One major point needs to be mentioned here which was so far not brought up: - of course the bearing of ANY turntable trying to bring out anything near the best possible must be TOTALLY free of any force in horizontal direction.
In other words - free of any force vector.
In plain words - there MUST be a counterpoint creating the very same force as the belt, thread, string etc. from the exact opposite direction and thus elimination that force to total zero.
Before this is not done, we do not need to talk at all about variations in speed, stylus drag, etc.
A direct drive doesn't have that problem of course.
Due to the fact that the act of playing a record does indeed brings the record into vibrations we need a heavy platter ( thats why heavy platters - if of any quality - ALWAYS do provide more substantial sonic information in both frequency extremes).
This platter must be - seen as a body - as insensible to vibration as possible. Consequently we are leaving the shape of a flat disc and platter and strive (if possible ....) towards a "round" cubus or (theoretical ideal) ball. To further increase the insensibility to vibrations other than shape is creating a compound "platter" made of materials of very different resonance behaviour
These are basic fundamental physics and nothing special.
The higher the rotating mass, less and less energy will be transmitted ino the platter.
If teh record is clamped firmly to the platter we (in an ideal situation...for which we can strive...) see the records mass being part of the platters mass. Thus less and less information will be dulled and smeared by a vibrating record (as Kirkus will agree, this is very similar model to a woofer working in a rather light and resonant wooden cabinet compared to mounting it in a stone wall - we both know that the dynamic, detail and clarity in impulse is dramatically different in these two mountings. It should be clear why.) and the pureness of information is greatly enhenced.
The point of suspension from outside mechanical resonance (building resonance) was discussed earlier and the solution is simple and can be obtained as a lug-and-play solution from suppliers already mentioned.
2) A turntable does not provide good sound.
A turntable has to had no sound at all. As above stated - all sound and music (should...) come from the LP itself. All the turntable can do is not ruin it. A good turntable is a dead turntable (as regarding sensibility to vibration and inner resonance). There is no such thing as a "good sounding turntable" or a turntable with "emotion (aside from its outlooks...)" or with "rythmic drive".
I mean these turntables may sound "good" and give the impressions of the above mentioned sonic features.
But they only allow these positive features to unfold.
They are in the record.
The other TT's just destroy and dull them in one way or another to more or less extend.
3) Nowhere is the relation between "good sound" and pure physic as easy and as direct as in the turntable.
I will always agree that there are tastes and many different ways to reach (Rome...??) excellent sonic results in speaker design, amplifiers and cartridges (I am less generous with tonearms.....) - and yes, we do indeed NEED distortion in amplifiers (2nd harmonic order..... only.).
No so in turntables.
Its all physics here - no mystery, no genius, no secrect, no ideology.
And again - if we are talking designing a turntable as a "product" for a "market" with "value for money".
Well, - than this discussion is futile from the very beginning.
A turntable very clos eto perfection CAN and WILL be build.
But it will NEVER qualify for a commercial product.
We do not need to compromise because the turntable is so difficult to build.
We need to compromise to make it to a "product".
Because here some people must have their financial share.
The product is the compromise - the compromise is not nessecary per se.
4) A turntable does not sound.
It allows information to be extracted without alternation - or it fails in some parts or many.
Allowing some parts and smearing and dulling others results in a "sonic signature".
All other parts of the audio chain do indeed have sonic individualities - cartridges, cables, amplifiers, speakers. All these are either elctrical devices or transmitters between the mechanical and electrical world (cartridge and speakers).
Not so for tonearms and turntables.
They are purely mechanical devices.
And we can make them closer to perfection as any other part of the audio chain.
We just have to be consequent and dare.
As for the perfect turntable - in the words of your new president: .... yes we can.....
I totally agree with you that the high mass platter does make the motor / belt / thread less critical.
But if you combine a super high quality motor with excellent power-supply with a really heavy platter and superb bearing and drive counterpoint - then we getting close in bring part one of the system close to perfection.
This is very significant regarding a vibration and force free system - and thus - after all, significant for musicality. |
Yes, aramid fiber: http://scientificsonline.com/product.asp?pn=3034863&bhcd2=1232817787
Raul. |
Dear Dertonarm: I agree with you on your TT approach. IMHO this is a " road " to follow but IMHO it is not the " only and best " road. There are other examples speially on DD TT designs and certainly there are other " roads " in the brain of TT designers that they are not try it yet.
I agree too with Teres that physics tell us part of the whole " history " but there are several factors that affect and change what we are hearing it does not matters if the physics is on target, of course that everything the same a TT or any audio item that achieve a scientific approach is a better one and has to perform in better way too.
IMHO I think that are many " things " that till today no one already made a in deep research to find in a scientific way the. why's, where's and how's on each single TT design.
I know this because is something that I'm learning through our self tonearm design, where I'm " discovering " things that I never imagine can/could affect to quality performance.
Well, IMHO that happen too with TT's where scientific rules/law can't give us all the answers ( relationship factors ). Of course that if someone makes the research can/could have scientific answers but maybe to find out all those answers he will need not only know-how but a lot of time,money and common sense.
I like you and almost all people that cares about top quality performane/designs hate compromises/trade-offs but unfortunately these ones exist and the best each one of us can do is try to choose the " best " overall ones: such is life!
Regards and enjoy the music.
Raul. |
Dertonarm, I completely agree with you that the job of a turntable motor is only to bring the platter up to speed and then keep it from slowing down. Where I disagree is that platter mass alone is the the cure all for speed stability. A large platter mass does not negate the importance of motor quality or the quality of the drive mechanism.
In this thread there is a lot of discussion about physics. Of course what is happening in a turntable is about physics. But I posit that good turntable design cannot be purely about physics. There are several reasons that this is the case:
1) Nobody fully understands exactly what the physics are. There are a lot of very subtle things going on in a turntable that to date are not fully explained. There are plenty of theories and opinions, but not a lot of facts.
2) Good turntable design is all about producing good sound. Unless the relationship between sound and physics is fully understood then physics alone cannot be an effective method for designing a good sounding turntable. Harmonic distortion in an amplifier is physics. But building an amp with super low distortion often does not produce good sound.
3) Design is also about compromises. There are compromises to control costs that apply to any turntable design commercial or otherwise. A good designer will make the compromises that deliver the best value for the money and effort expended. In addition to cost compromises there are compromises related to balancing of conflicting technical goals. Coupling vs isolation, damping vs rigidity, light vs massive. Focusing on only one objective usually delivers poor results.
4) Like it or not good sound reproduction is a subjective pursuit. There is no such thing as an ultimate sound system nor is there or will there be an ultimate turntable. Everybody has their own set of musical priorities and no design will be a fit for everyone.
Back to platter mass I have done a lot of experimenting with various platters. I find that to my ears heavier platters do sound notably better. I also have found that a heavier platter makes that quality of the motor and drive system less critical. But even with a 70 pound platter subtle changes like belt material and even the motor pulley composition are still easily heard and are musically significant. Less subtle changes like rim or direct drive are even more obvious. |
In fact Micro Seiki 's engineers were the very first to realisze the potential (in turntable design...) of high inertia coupled with thread drive resulting in superior extremely constant speed. Low grip, slip coupling and let the huge mass in rotation do stabilize itself.
I mean - it works pretty well with our planet (and a few trillion other planets too.... yes, I know - there is no stylus drag on terra..... and it is a rotation in open space = vacuum) - why shouldn't it work with our turntables??
But again - you can not do it cheap.......... huge mass platter ( = expensive), very strong yet high quality bearing to handle huge mass platter (= expensive.....), high quality motor (good capstan - for instance...) (= fairly expensive again).
Not to speak about suspending the combined high mass with super low frequency from building resonance...... |
As for the Micro Seiki original belt / strings. The Micro Seiki RX-5000 came first with a fairly strong and wide rubber belt of very high quality first. However they did recommend too - right from the start - using an aramide string ( made out of 134 individual fibres ) to get the very best results possible.
Because of less vibration transmission towards platter - and: slip coupling....... resulting in much better constant speed....... |
