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. |
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. |
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. |
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. |
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. |
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... |
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.... |
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 ? |
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 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. |
Sorry: think and live at the last sentences instead of " thing " and " leave " .
Raul. |
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. |
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. |
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. |
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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...... |
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. |
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. |
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 ! |
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.
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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.
|
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. |
###
- 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... |
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 ....... |
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 $. |
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 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. |
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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
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Dear Dertonarm: This is not a contest ( like you want to be ) on who have the reason or who knows more about.
I posted that I'm not ( yet ) on the TT design. Right now I don't know if there are better alternatives and which ones are even I can't say that your is the " one ".
Right now I'm a " spectator ". I have several " ideas "/common sense that are the ones that I will follow when we start our TT design.
What have I on hand?, almost nothing. My TT design is on " desk " waiting for like the amplifier one. Each thing at its time.
I'm not saying that your approach is wrong what I'm saying is that it is not " the best and only way ". In the time we already finish our research on the TT and start the design, tests, execution, tests, tests, test, then I will have a more precise arguments that exist other alternatives that can even and can outperform the ones that exist today including yours, not before: I don't have the " cads " yet.
No, you don't do nothing ( steped on... ) in the FR that is a " so so " design even with its own FR cartridges. No, I don't want comeback to this subject, I point out only because you name it again. I posted that when we obtain the patents on our tonearm design I will share with everybody, not before, science is science.
+++++ " 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? " +++++
I don't need that you convice me, normaly I take the steps by my self to convince me about any subject that has interest on what I'm trying to achieve.
I don't care and means nothing if you name some materials with out scientific tests that prove/establish that that combination of build materials and its inter-relationship ( platter, plinth, bearing, arm board, footers, etc, etc ) are dead NEUTRAL below any real playback work conditions.
I think you can't do it, I mean that you don't have it, do you? .
Now, if you have it I don't need that you tell me, sooner or latter I will find the answers ( maybe a different ones from yours and maybe some like yours. ) about when we are in deep in our design.
I ask about only because you don't touch this " main " TT deign factors. I wonder why?, perhaps another un-finished/futile TT design?.
IMHO all our un-finished designs ( protoypes. ) have a very important " steps/role " in the final product and that role is that through these prototypes we can achieve our targets to build the real FINISH product.
I have some Phonolinepreamps and tonearm prototypes where I can " read " the different steps that bring me to the final product.
We have many differences in our way of thinking ( between you and me. ) and one of them is that I never think that I'm at the end of the audio item learning curve final design, at least I never experienced that I'm there.
I have my dream phonolinepreamp design like the tonearm, cartridge, TT and amplifier ones. These " dream designs " are perfect ones and wonder what? are commercial ones too but we need time a lot of it to make those " dreams " come alive but my final " prototypes " are a good step on the right road.
I can tell you that if I was Matushita Corporation where I can have any kind and any quantity of resources for audio projects then maybe in two-three years those " dreams " comes true but we are two-three persons that make this job in our free and just because we like it and enjoy what we do about.
Anyway, like I already posted go on: many people here are having fun and that's good. It will be " futile " if I try to go on. In good shape: thank you for your time.
Regards and enjoy the music.
Raul. |
I thank all the participants on this thread for sharing their knowledge and experience. Sitting on the perch of not being willing to build my own TT, and not being willing to spend ultra-bucks to buy someone else's summum, and being quite happy with what I have, I am very happy to hear a variety of opinions and experience because I am learning a lot from the discourse. I think if EVERYONE took a step back, they might learn something. Because people are coming at this from different perspectives, they seem to be getting their noses bent out of shape. Almost everyone here except Dertonarm is coming at this from the side of what is commercially viable (either because they need to make something commercially viable, or because they need to buy one which is made by someone else). Dertonarm is coming at it from a different angle.
Years ago, I read the Teres Project archives. They were extraordinarily enlightening to me at the time. I found dissenting opinions, and well-meaning hypotheses which turned out to not work, but in the end a lot of openness to challenging the existing ideas in order to create something better. In the end, those better ways were created (and I would suggest Chris Brady and recent Teres model purchasers believe the Teres Project results are still being improved upon) through hypothesis and trial. The results were that through astute selection of materials and drive system, an excellent TT could be built which was less expensive than the otherwise self-declared state-of-the-art. I would assume that subsequent models higher up, which garnered much praise by people with great systems improved upon the first renditions. It is obvious through Chris' assertions here that he believes his new DD system, and perhaps others', improve(s) upon those highly-praised BD TTs). I am sure they do. The fact that they are still being improved upon means that everyone is finding better and better ways to skin the cat. Dertonarm's main point is that the cat is still the cat (unless, of course, it is Schrodinger's cat, in which case, it may not be), and that there must be a 'best way' at some point (assuming that everyone's measure of 'best' is the same).
I think that Dertonarm will not deny, disavow, disagree, or demean anyone's opinion that a given DD motor driving a high-mass platter can sound better than a given belt-drive high-mass platter system. I am pretty sure that what he is saying is that he has not found it to beat his belt-drive high-mass platter and he has found the compromises in the DD method to be greater than the compromises in HIS BD HM system. Dertonarm has, in every thread, refused to comment on what he thinks sounds better (partly because it is beside the point I expect), but consistently appears to be looking for someone to provide technical input or results rather than an opinion or the result of System A having been better than System B (which is not so much a demonstration of physics as a demonstration of implementation). Trying to critique his results as invalid because he still finds compromises in it is also beside the point.
So far, the fault I find in Dertonarm's discourse is the assertion that DD or idler drive would not work with "highest possible platter weight" and using "high inertia for self-stabilized speed." It may be right, it may be wrong. It is, however, not defined nor supported. If there is a mechanical slippage system (slipping belt drive) there is, by definition, a compromise. In my opinion, the PERFECT implementation of a TT would not use mechanical slippage. It would also not depend on electromagnetic slippage. In a perfect system, it would be pure 100% speed-stable drive. I am assuming his assertion is based on his experience that mechanical slippage may be a smaller compromise than building a system of electromagnetic slippage with no mechanical slippage. In any case, let's see the technical reason why such is the case. I, for one, would expect that one could build a very very good DD HM system given enough time and enough resources - though in the end it comes down to motor speed/torque stability and whether that stability is greater than the speed stability offered by a 'clutch' system of thread slippage.
While Dertonarm's conclusions appear to be 'dogmatic' to some, they appear to be the result of trial and experience. His tone may be dry, and that seems to antagonize some people, with somebody now suggesting he has an 'agenda' (similar to the way some people 'have an agenda' with tubes and OTLs, and others with single driver loudspeakers?). I personally do not see 'constant demeaning of dissenting opinions' so much as I see challenges to demonstrate that opinions are backed with technical results. I am sure that if someone could prove that a DD with high mass platter had better speed stability than a thread drive, many would be interested (including Dertonarm). It just happens to be that while some people profess that such a thing is possible and they have heard it with their own ears, someone else thinks it is still a method with less accuracy than is available than through what he has done himself.
I would encourage everyone to look at these discussions the way they might if they had participated in the Teres Project Archives email exchanges. There is nothing wrong with dissenting opinion (and I for one do not see Dertonarm's commentary to demean dissenting opinion), but Dertonarm's whole point is that he is striving to improve upon what exists, not prove that one existing thing is better than another. His question to all is whether anyone can demonstrate that one method is, in a technically definitive way, superior to another. |
Frank, I for one hope you do not regret chipping in. I always enjoy reading your informative posts. As to your last point, I completely agree that in coming up with a commercial product, there are always compromises - it cannot be otherwise as there is always the cost factor (and while I agree with your comment about not everyone designing to a price point or saying 'that'll do', unfortunately, that is inherent in some way in every compromise). As to your point about belittling people, I did not see it that way so much as I see people having two conversations which don't mesh. Most people in the real world and Mr. D in the theoretical. I, for one, am not at all convinced Mr. D is right (though I would love to listen to the table he created) about high mass BD (even though my preferred TT at home is a HM BD with slipping thread drive). I expect DD is probably 'better' because I expect it is easier to control the electromagnetic slippages than the mechanical ones. However, this is based on a total lack of experience doing it myself so I for one, encourage real, technical discourse.
A last technical question to you, Frank:
If you put in opposing pulley/threads, why would all 4 resonate at the same frequency? Would not the drive (pull) side have a different tension than the 'lag' side - thereby making same resonance on 4 strings impossible? |
Dear Raul, if this were a contest (a contest about what ? Knowledge ?) - it would be fairly boring.
Aside from this there is nothing in your last post which requires any response as there are again (as so often..) no facts and nothing which has to do with the topic of this thread but only with personal animosities.
Boring. |
Dear Dgarretson, before I get off for holiday, - first of all: very nice set-up you have done with your modificated TNT. There is much more insight and mechanic knowledge displayed in your set-up, than in many comments posted on that topic here in the last days.
As for the denier of the aramide thread.
It depends on your intention regarding the amount of grip you wish to have on your platter. With your set-up the thread does entangle the platter for 5/6 of its circumfence. I would start with a thread about the "thickness" of a sewing-linen. This will run smoothly through the pulley groove of the VPI motor and will give "fairly" good grip without becoming too massive. Aramide thread have become so inexpensive and widely available ( it was a very different situation 18 years back.....) - just get a selection of 3-4 different strenghts. For best comparism - why don't start with a aramide thread excatly the strength/thickness of the string you are using right now. That way you get a direct "result" as for any sonic benefit/or possible drawback of the aramide in your given set-up.
I really am interested to learn about your findings.
Please let me know. |
Dear T bone,
>Would not the drive (pull) side have a different tension than the 'lag' side - thereby making same resonance on 4 strings impossible?<
You are correct if the thread has stretch and is under tension. Dertonarm suggests the use of a thread with no stretch and advocates low enough a tension to allow for slippage(if I misunderstood, I apologize). Both longitudinal and transversal waves contribute to the vibration of a connecting medium(be it a rubber belt or a thread), modulating the load "seen" by the motor. The ratio between the two differs though. Since Dertonarm was approaching the discussion from a theoretical point of view and has emphazised individual aspects, I thought it would be fair to point to conceptual flaws as he has asked everyone to do.
But he has built a turntable following his dogma, appearently without running into a problem in this area as he said that achieving and maintaining correct(or what he considers correct) thread tension was not difficult. Complextity and resulting chaotic behaviour of elements working together can come to rescue here, rendering a theoretical problem nonexistant in praxis. Dertonarm was asking for input on how to improve upon existing solutions and my suggestion was merely aimed at that.
As a designer my aim has always been to avoid a source for problems rather than quantitatively minimizing the problem. I've built turntables with thread drive and counterpulley in the early eighties and later commercial implementations of the mirror image positioning of the counterpulley all fixed some major issues - side thrust on the platter bearing, uneven operation of the subchassis(Audiomeca Roma) - and introduced others - noise, belt "flutter", slippage(where none was intended to occur).
BTW, a platter driven by a constant stream of air will be harder to build and not necessarily better than one with a pulsed supply. If the pulsed supply works against, lets call it "teeth" or "wings" of appropriate shape, a very even drive force in agreement with Dertonarm's dogma can be achieved.
If the system losses are small enough and the inertia very high, such a pulse can occur only once per revolution or even less frequently.
One could see an analogy between tts and high precision timekeeping devices. The astronomical regulator with a "free" escapement and heavy(high inertia pedulum) driven with minimal force(keeping the drive system's influence small) stands for Dertonarm's thinking, the low mass high frequency oscillation of a quarz or even Cäsium atomic clock for the quarz-"locked"(it's not locked) instantaneous(it's not instantaneous)correction direct drive with light platter.
The atomic clock produces ultimately less deviation from perfect accuracy. Now why then do the best DD-PLL turntables with light platters(i.e. EMT 948) sound inferior to the best DDs with heavy platter or the best belt, tape, thread or rim driven turntables? Lack of proper execution or fundamentally flawed? This seems like a rethorical question, but it isn't.
If your motor has infinite inertia(god brought it up to speed initially...) and your drive is lossless, then your platter can be infinitely light, will be infinitely inert and therefore rigid as well. No more energy storage or mechanical impedance matching problems(topics for another thread), Yeah! :-)
I'm gonna run, create an avatar to build this theoretically perfect turntable in cyberspace. Not shure I'll be digging the music over there though...
Cheerio,
Frank |
Frank, thanks. My understanding, from Mark Kelly's interesting writings on the subject, is that no matter the tension, some kind of slippage is, by definition, necessary; and that slippage induces differing tensions on either side of the platter, by definition - or perhaps I misunderstood his various writings - I would not put it past me :^)
I am intrigued by your pulsed air and finned/winged/etc underside of platter concept. Personally, I would expect substantial cogging potential from the airpump power supply, and other sources, so would (not being burdened by any practical experience in the area) avoid intentional pulsing. I would expect that running the pulsed supply through a series of buffer tanks would get you to your constant air stream with more accuracy, and if you ran that through the same 'toothed' underside which had a very tight tolerance for the space between the downward-facing 'top' of the tooth and the upward-facing air inlet area, it would serve to pulse the air as well, but as long as the air-pressure post buffer tanks were constant, and applied at several (or more than several) places under the platter in regular syncopation, it would go a long way towards lessening the impact of variations in the air pressure coming out of the tank, and if it was a high-inertia floating platter, the 'teeth' could be oriented to receive air pressure which would self-center the platter. The amount of air pressure necessary for the drive system would actually be quite low. One could set it up so that the platter got to speed through some other system, which was then clutched 'off' when the air pump took over. I guess the question is how one would 'brake' the platter using that system, other than using its own inertia, if one needed to...
As to your non-rhetorical question, my gut is that the qualitative differences between DD-PLLs with light platters and the best of the other types with heavy platters may have to do with the audibility of the speed of speed correction, which is where the inertia comes into play...
In any case, have fun in virtual reality |
I would think that an "air drive" platter would not opnly be difficult to get started, but if it got spinning too fast would also be hard to slow down to the proper speed. The platter would have to have a wee bit of friction I would think.
A push with the hand is really not an option to start off unless there was some minor friction. You would want to have the speed build up and stabilize, so low to proper speed is the goal rather than high to proper + friction.
It is a rather intruiging proposition though, although the "friction" of the air on some form of wing under the platter could cause a rumble of sorts and a cogging effect I would assume. Not without its flaws, but probably the next $100,000 turntable idea. Anyone want to come up with a business plan?
Bob |
Hi again,
Mark Kelly is correct about the tension differential, provided the thread/belt does stretch and that there are frictional losses in the platter/bearing system. I don't think he said that slippage was neccessary, but rather that it was unavoidable in real life(maybe I got that wrong...)
Slippage can be avoided, idler, belt or tape creep can't.
My comment on the counterpulley symmetry relates to Dertonarm asking for a debate in the theoretical domain. I made it the sake of debating idealized concepts rather than compromised implementations(called reality), please take that into account.
A single constant airstream working against "wings" will cause cogging. Two(or more), 180°(x°) perfectly out of phase air vents with proper orientation of the wings will cancel the cogging(don't want to be responsible for the maschining of that one...). But this isn't all that different from a conventional multipole motor.
A single leaf and a one impulse(or 0,5, ...) per revolution is different. One could achieve the same without the complexity of an air supply, the turbulence issues, etc. by using a very heavy platter, direct driven with the motor being switched on only infrequently , be it for a very short duration or ramped up, then down again, but only when the speed drops below a set deviation threshold. Oops, I see the word feedback on the horizon, mmh...
The inertia of the platter will be an intergrator again, the constant motor noise/mechanical jitter will be exchanged for an occasional pulse and the bearing losses ought to be zero ideally.
Low frequency pitch stability will once again be less than perfect :-(
There again, it contains compromises... I'm still tempted to build such a device(and sell it for --- ONE GAZILLION DOLLARS, buahahaha...!).
A pulsed air supply with transfer function matched "wings" won't cause cogging IF you solve the problem of syncronisation(and if there was no such thing as turbulence, a.k.a. CHAOS).
Now back to "real" work :-)
Frank
P.S.: Related to the original post: There are at least 6 different currently manufactered turntables that partially rely on creating additional drag on the platter for maximum speed stability. |
Berlinta, T_bone, Raul, Dave, et al: Do you all except Dertonarm's contention that belt drive is the inherently superior way to motivate a platter, compared to all forms of idler- or direct-drive and notwithstanding theoretical air propulsion? It seems as though you all do. I don't, yet. T_bone, I think it's very significant that Chris Brady reports that his belt drive tt, and his rim drive motor when applied to his heretofore belt-drive tts, outshine any of his belt-drive creations, which are themselves held in very high esteem among end-users. I don't think his real-world experience should be dismissed BECAUSE it is anecdotal, if I understood you correctly. Rather, these are good data that have to be explained. The escape clause for anyone who wants to hang onto his or her own bias, is that perhaps none of us has heard the "ultimate" belt-drive tt. |
Please take into consideration in all discussion about what drive and platter weight that is is not alone about constant speed.
There is the "2nd system" (mentioned before ) and its energy transfer into the platter: - the act of extracting information from the groove by the stylus. There is more to the platter than (high) torque, inertia and constant speed.
It has to handle complex energy transfer (and/or damping) provided by the stylus demodulating the groove.
Bringing this into consideration will clarify some points which came up in the last posts by Berlinta and T_bone. The high mass platter plus the low tension thread made of aramide or similar will too give some answers, why there is no problem with vibration or resonance being transmitted or initiated by the thread.
As for the hypothesis of the high inertia (which is fully backed and put into "half-commercial" product by Jean Constant Verdier in his Magnum ) providing close to ideal constant speed, it would be helpful if Kirkus - who is respected by us all - could clarify or illustrate the point.
If I try it might soon become too dogmatic again.
I am on holiday now and will - randomly and infrequently - follow this thread, but I will make no personal remark to anyone anymore and will not answer to any directed to me either |
Hello Lewm,
No, I don't agree with Dertonarm's contention. If you reread my posts, you'll find that I'm trying to point out that there are several ways of approaching the challenges to run a platter at constant speed, ALL of which are flawed in one or several ways, as soon as we are dealing with reality.
I am very much familiar with Chris's table, in fact I suggested the use of an eddy current brake acting on the platter as soon as he started making platters with brass or aluminum bottom layers and I heard both a prototype and the first production model in comparison to his then top of the line tape driven tt. His direct drive turntable offers exceptional speed stability(significantly better than his tape driven decks) and is proof that it can be done(and, again, look at one of the last generation cutting lathes).
I'd prefer to discuss real world experiences, but Dertonarm made such a big deal out of the supposed mediocrity of most, if not all contemporary turntables that there simply was no point in "getting real".
Strangely, I have not gotten a response from him...
Best wishes,
Frank |
The "air-pulse" drive (no pulse would exclude a problem) has some considerable problems while looking close to a theoretical ideal first. It not only will require considerably (really serious...) periphery, but indeed a "assist"-motor to bring the (high mass) platter to requested speed first and than de-coupling. The question is whether it really will provide a "better" drive mechanism - as fascinating as the idea itself is. |
Lewm, regarding my belief in Dertonarm's contentions... if you look at the first paragraph of my second of two consecutive posts above, I state... I, for one, am not at all convinced Mr. D is right (though I would love to listen to the table he created) about high mass BD (even though my preferred TT at home is a HM BD with slipping thread drive). I expect DD is probably 'better' because I expect it is easier to control the electromagnetic slippages than the mechanical ones. Regarding Chris Brady's DD TT... in paragraph two of the first of those two consecutive posts, I state... It is obvious through Chris' assertions here that he believes his new DD system, and perhaps others', improve(s) upon those highly-praised BD TTs). I am sure they do. I, for one, would love to have the chance to listen to that TT. I am sure it is fabulous. All the anecdotal evidence points to a conclusion that he has made one of the top commercially available TTs out there. But your next point: Rather, these are good data that have to be explained. is the crux of what I was trying to get at. I believe that Mr D's point is that anecdotal evidence of one or two commercially available TTs sounding better than another couple of TTs is fine, wonderful, and nice, but beside the point. He has asked for technical arguments WHY DD should be less of a compromise when attempting to create the perfect TT and so far noone has come up with the technical arguments, the physics, or experimental results detailing why that should or could be so. I think he would welcome the philosophical debate. I know I would. And yes, I think the escape clause for most of us will be to say that we haven't heard the best BD TTs or DD TTs out there. But again, for Mr D, that is beside the point. I may not agree with his assertion that high-mass thread-slippage BD TTs are the best method to approach perfection, but I have no science or experimentation to back up my disagreement, so instead I hope to learn. Cheers, |
Indeed Berlinta, you did not get a direct response.
You did not ask for it either.
I layed out all the points the days before. I could again answer to all the points in your last 4 posts. But I do not see any attractivity to repeat myself over and over again. All the answers were already posted in this thread before the questions came up.
It will not be to the benefit of this thread - especially not right now as it is finally back to technical discussion again - if I post direct response. Rereading some of my earlier posts will show that the answers are already there. They just got "buried" in the interim when the discussion left the original intend. |
Dertonarm:I knw that is more easy in this way because you don't have the precise-scientific information/tests on the " neutral " build materials that are very important part on any TT build/design. Yes I know your answer: futile.
Regards and enjoy the music. |
I do have a file - 3" thick and 8 lbs heavy - of extensive test and data sheets to about 5 dozens different materials which at one moment or another were part of the turntable design pre-thoughts (some finally made it). However I remember that one particular poster stated yesterday:
"I don't need that you convice me, normaly I take the steps by my self to convince me about any subject that has interest on what I'm trying to achieve."
I respect that position. |
Air would be a poor choice for a drive mechanism since it is compressable. Hydraulic fluid on the other hand is not compressable. Driving the platter with hydraulics would be an alternative choice. A pressurized bearing could also be utilized.
I'm not a turntable expert, just a bmw tech. I believe some models of Jeep/Chrysler used hydraulic cooling fan motors powered by the P/S pump due to the fact they are quieter. Perhaps a similar system could be made for a turntable? Just throwing out ideas. |
Dear Rhljazz, a fascinating idea. This is something really worth discussing. You happen to have any links to technical exploration and the required periphery? |
