Dear @moonglum : Achilees heel in fixed/gimball tonearm bearing designs?
Well, as in any tonearm design all depends on the design it self and the quality excecution level of that design.
In the fixed tonearm bearing design there is no inherent achilees heel as in all true unipivots. Gimball type tonearm bearing designs can comes with " mistakes "/bad design in that regards but what is happening down there and that you explain in wide way ( brinelling. ) is not inherent to those kind of design.
You can take for an example a vintage tonearm design as Technics where the designers decided to use four bearing points and use at each bearing points 5 ruby balls ( 20 in total. ) with a roundness tolerance of 0.5u that permits a bearing friction number ( in all directions. ) of less than 5mg. and it´s not only that but all the care Technics took for its production. A superlative product that even today is the " envy " for any tonearm manufacturer.
Brinelling there is almost non-existent. Of course that there are truly bad designs as the FR tonearms that in that regards is one of the worst examples you can find out but even this those stylus tip/groove huge forces makes that the tonearm moves!.
In the other side, the very tigth tolerances on today gimballed designs makes that you don’t have to worry about. In the past almost no one use ABEC 9 balls and today is a must and almost every one use it at the tonearm bearings.
Everything the same unipivots are in total disadvantage against giball/fixed bearing tonearms.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
Bill / Moon Very interesting post. I remember owning a Helius arm...very high priced, but a miserable design.. It went back to England 4 or 5 times before I sold it.... it was gimballed and was supposed to be the second coming. I had trouble with my ESL, Zeta, Rega, (gimbal) but never had any trouble with a Grado Labs or 3 different VPI's... (unipivot).
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Hi Raul, I agree with your earlier statement that there will always be trade-offs. My main reservations about gimballed bearings are “brinneling” & stiction. 40 years ago when I was making my earliest forays into “serious” hifi, “Flat-Earthers” would talk of how low output, low compliance cartridges (such as those popularly from Linn) could “wreck” the bearings of lesser tonearms i.e. those with poor(er) quality, loose bearings such as the old Rega “S” shape. For this reason one could never use such an MC in such an “inadequate” arm. And so the era of the so-called “Super Arms” began (Zeta, Ittok, PU2, etc). I owned several of them. I am no longer a “Flat Earther” but brinneling hasn’t died, more “ignored”(optimistically) these days, especially when buying a S/H example 30 yrs old...
The Linn arms in particular tended to be run “dry” i.e. no bearing lubricant. This probably wouldn’t help very much, so, if poor reaction to warps is the (simple)Unipivot’s Achilles Heel, then brinneling could be defined as the gimballed tonearm’s Achilles Heel #1. Achilles Heel #2 is probably, amongst other things, the result of the engineered solution to brinneling : forms of increased friction. https://en.wikipedia.org/wiki/Brinelling To me, Stiction sounds like an invented word rather than a real one but gimballed arms often have it. There can be moments when an arms ability to travel in either axis is hindered by a reluctance to move under light impulse. It was one of the reasons I switched to unipivots, because I could actually see it for myself in bearing tests. This can be attributable to long term bearing damage, deformation of the housing, contamination, drying out of lubricant (if applicable)etc. When you have a situation where the LP is drilled off centre, the tonearm is suddenly presented with the problem of tracing/weaving from side-to-side in addition to handling the warp. Given the possible presence of stiction and the enormous forces mentioned in your article this will be compounded by inertia and, in some cases, fluid damping. The end result will be that, often, the arm doesn’t respond fast enough and the pressure on the groove lining is ramped up, multiplied to even higher levels as the locus of the arm switches from pressurising one groove wall to the other? Surprisingly, our ears seem to be fairly immune to such effects, just as they can be with the forementioned bearing wobble. In fact, purists may pick up more on pitch errors due to non-concentricity than they might SQ differences resulting from variable pressure? Forgot to mention what may be categorised as Achilles Heel #3. When a warp occurs it usually emanates as a (lateral) angular undulation orientated from the LP centre to the outer rim which diminishes as we reach the inner groove. During this time a gimballed doesn't even operate in the same plane/angle as the warp, so it has lost its precise relationship and alignment with the groove. It's stable(!) but that's it! (Note : this behaviour would include the arm that I currently use despite it being a unipivot)
In conclusion, Unipivots can offer more “certainty”, even if some of them do have an “Achilles heel”. I’m always acutely aware of the need to avoid damaging gimballed arm bearings so wouldn’t even tighten a cartridge screw without stripping the arm completely from the T/T first (and if it possesses a captive cable, that too!) :^( Despite doing it countless times in pursuit of perfection, whenever removing a gimballed tonearm I still resemble a munitions man defusing a bomb! :^D Others may find it less nerve jangling but I don’t (not when I “paid an arm & a leg” for those bearings! ;^) There is no question that many unipivots are much more facilitating and user-friendly in this respect. (Of course if one has interchangeable headshells then easier swapping but small prices to be paid on resonance & rigidity).
Finally I stress that I LIKE certain gimballed arms, I like certain gimballed arms with interchangeable headshells and I like certain unipivots. I also like some hybrid arms that don’t fall into these exact categories. I guess the upshot of all this is that there are no easy answers, just compromises, as you said. Best regards & happy listening. Bill. |
Don - I know about everything..
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"take the best quasi-unipivot design and the best fixed one and through an electronic microscope in slow motion see what is happening at the stylus tip/groove on playback becaause at micrtoscopic levels you, me or any one can't see if exist that wobble in those unipivot designs.
At those microscopic levels we can see that the stylus tip is literally " jumping " in the grooves when ridding and between other things that's why is so important to achieve always a " safe " resonance frequency number between the cartridge/tonearm."
This is so funny again Raul you crack me up when you say "we" who are your speaking for please name these people. After you do that please post a link to a video that shows what you theorize here that is part of your many theories of analog reproduction that exist only in theories and only in your mind and never are backed up with any "facts" other than some funny quote you lift from another website. Raul I do not mind that you share your theories they are very funny actually but your problem with them is you confuse theories with fact and you pretend to speak for other "experts" who you do not name but you never hesitate to demand proof from others about what they sau or you dismiss their opinions because they lack the first hand experience you claim to have but never provide proof of.
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"The important issue here it's that the skate force exist through all the cartridge ridding in a pivoted tonearm...we just can't say: I like it more with out the antiskate mechanism."
For goodness sake Raul yes yes yes we an say that we prefer to use a pivoted tonearm without anitskate because everyone has their own opinion and in fact quite a number of experts who actually manufacture key components to our Music Reproduction Systems say that very thing I am talking bout experts such as Harry Weisfield and Peter Ledermann at Soundsmith these are people who have actually developed products for use in analog-based Music Reproduction Systems and are not simply theorizing from the comfort of a couch in there parents basement! Of course in your world Raul it is all about theory and you rely on developing theories based on others theories but in the real world where actual facts matter things are not so simple so please stop telling people here what to think and instead tells us what you think and maybe WHY you think what you think based on actual experience instead of your idle theories thank you! |
Dear @stringreen : Yes, for years I had the same kind of experiences through several tonearm/cartridge combinations.
The important issue here it's that the skate force exist through all the cartridge ridding in a pivoted tonearm.
That skating vector is part of all the different kind of " forces " that has influence in the stylus tip groove ridding " job and we just can't say: I like it more with out the antiskate mechanism.
Again, I'm talking on what we need to do or better: what the cartridge stylus tip needs and not what we like it because as " usual " we are accustomed to higer distortion levels that what we can think or imagine it.
Perhaps a " trouble " with AS mechanisms is that the developed skating force is a variable one all over the LP side and at each groove is changing and for that skating force can't has real influence we need a very preise antiiskating mechanism that can mimic exactly the inverse skate range at each groove and till today I don't know any single tonearm that fulfill that needs.
But all those does not means the cartridge ridding does not need it because we are talking that we have to have extremely care for the stylus tip pick-up precise groove information and the AS if not compensated goes against that target.
I know, that the AS task is almost imposible to do it in the rigth way.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
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I've had the second pivot for a few months now and have another on the way for my spare arm wand. It's easy to hear the difference and if you don't like what you hear it's easily removed. |
Raul....Interesting that you mention your objection to VPI arm regarding their serious needs for anti-skate. I've listened carefully with and without anti-skate on my metal 10.5 arm, on the 3D with and without the 2nd pivot and in all cases, the sound to my ears is better with a/s removed completely. I've listened a number of times but once I heard the difference, it was clear, I did not want a/s on my arm.
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Dear @folkfreak : So, those tonearms are not any more true unipivots ( good. ) but neither a fixed/gimball design.
Anyway, anything out of an unipivot design is just better by a wide margin.
What can be really interesting on the whole subject is to take the best quasi-unipivot design and the best fixed one and through an electronic microscope in slow motion see what is happening at the stylus tip/groove on playback becaause at micrtoscopic levels you, me or any one can't see if exist that wobble in those unipivot designs.
At those microscopic levels we can see that the stylus tip is literally " jumping " in the grooves when ridding and between other things that's why is so important to achieve always a " safe " resonance frequency number between the cartridge/tonearm.
I think that any tonearm must be designed to fulfill the cartridge needs. Understanding those complex cartridge needs.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
"
Imagine when in true motion ridding those grooves with all those huge ( every direction ) generated forces ! !"
I know you "imagine" these huge forces Raul but it doesn't make any sense perhaps you should check your VTF todays cartridges track around just a few grams there's no need for "huge" forces if you are using huge forces you are damaging your phono cartridge/stylus/cantilever assembly AND your records! Please get a modern tonearm with a properly matched phono cartridge and the forces you'll need to deal with will be on the order of around just a few grams give or take a tiny bit. Good luck, Raul! |
@rauliruegas is correct in pointing out that one of the challenges of designing a unipivot is addressing the question of lateral stability and providing for precise and repeatable antiskate. It is precisely these challenges that the designer of the brand of unipivots I prefer (Durand) addresses -- originally via the use of dual magnets to provide lateral stability and adjustment on the Talea and then through the introduction of a precision side bar (aka "2nd pivot") in the Telos and Kairos. The trick with the side bar is that it is engaged via an adjustable sliding weight so that you can set minimal contact force (or more if you so desire). Once this element is in place the rest of it, and frankly the cost, all is down to materials -- and yes the selection of materials in every place on the tonearm does matter. So I’m not surprised that the VPI with 3rd pivot sounds better but surely it would have made more sense to design this in from the outset?
By the way inspired by the video I also closely examined needle drops on both my arms (I have a Kairos for stereo and a Talea for mono) and both go straight down and land with no sign of any wobble 😉 |
"
Remember that I'm talking on what we like when listening to unipivots. "
that has an error ( my mistake. ) and must be read in this way:
Remember that I'M NOT talking on what we like when listening unipivots.
R.
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Dear @stringreen : "
I'm sure in the future, there will be even more modifications and applied engineering to bring tonearm designs to increased abilities "
I can't say it in better way. Agree with.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
"any tonearm suffers from that torional huge forces but the unipivots are where affects in the worst way to that very hard cartridge job."
Raul I can easily see why you promote this belief because how can you have stability when the stylus is lurching from ambient temperature to something hot enough to melt vinyl and then resorts to freezing temperatures as you claimed earlier? Naturally the expansion/contraction/expansion of the pickup arm as it dissipates this extreme heat and cold must be continually expanding and contracting and expanding and contracting and
expanding and contracting and so there can be no stability at all by your reasoning! Also, the "infinitely" tiny stylus combined with the "infinite" tracking force you mentioned earlier must also introduce instability because of the constantly shifting "huge" forces that are twisting the arm! It is amazing any tonearm works at all given all of the extreme forces you imagine are happening with all tonearms! What is the remedy for this Raul weren't you going to invent the ideal tonearm what happened to that effort of yours or are you still struggling with those "infinite" forces? Do please answer we all want to know I think about your efforts in this regard to achieve the perfect way to compensate for thehuge infinite forces.
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Raul.... I believe you are correct....that's why the 2nd pivot works so well. ...as to why the unipivots work as well as they do ....if one looks at a bautiful phonograph....even though it is clear and clean, when looking very closely, you'll see that it is made of many dots that all meld as one into that picture. Many listeners will be very happy with a unipivot on their turntable (I was)....but as you said...in finding and eliminating "possibilities" ..looking for the very best that can be done....the 2nd pivot brings us very much closer to the performance. That 2nd pivot increases dynamic range, widens and deepens the stereo image, solidifies the low end, stabilizes the images within the sound field, et al. I'm sure in the future, there will be even more modifications and applied engineering to bring tonearm designs to increased abilities, but for the moment, satisfaction can be found for most people.
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Dear @moonglum /friends: Torsianally stable?, any tonearm suffers from that torional huge forces but the unipivots are where affects in the worst way to that very hard cartridge job.
In any cartridge mounted in any unipivot tonearm design combination first than all puts the " possibilities " to be nearest to the recording really far away.
That item combination is more an acrobatic act that a listening experience. Unfortunatelly, that acrobatic act is made it with no real success.
We only have to think the total unstability that persé has any cartridge that rides through that very tyny stylus tip dimension and at the other extreme ( unipivots. ) side an inverted " stylus tip " that function as the pivot.
It's imposible to have any kind of stability in between, a stability that's a must to have for the cartridges can makes its job.
Even in static way an with the stylus tip in the LP with the TT spining exist no real stability. Imagine when in true motion ridding those grooves with all those huge ( every direction ) generated forces ! ! !
Remember that I'm talking on what we like when listening to unipivots.
Btw, damping can't disappear the unstabilities at microscopic stylus tip as pointed out Don.
Even, in the VPI case, its design comes not caring very seriously about the needs for anti-skate.
I think that unipivots were and are designed because are easy to design, manufacturer and assembly. Additional comes with low market price. Well not so in the price subject when exist unipivots over 20K and there are audiophiles willing to own it ! ! ! Incredible.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
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Don - you do not know what you’re talking about. I’m sure you are not a VPI fan, but if you don’t know what truth is, you shouldn’t post to steer subscribers in the wrong direction. Damping fluid in the metal VPI arms can be useful if you want to tune out a wart in your speakers, etc....in truth the damping fluid in a high end system reveals a closing in of the soundstage. Even with the damping fluid, the metal arms wobble.The metal VPI arms are very good, but the 3D’s are exceptional....ranking with the very best, even if they too wobble. If the look of the 3D is not pleasing, you can always glue diamonds to it....if the arm breaks, there is the VPI team that will readily repair/replace the arm. The 2nd pivot on the already excellent 3D that does not wobble,will make you want to re-listen to your records. I am a long time purchaser of VPI. I have a Supersoutmaster/rim drive/SDS/3D/2nd pivot. I even have one of their black VPI polo shirts that Harry sent me after helping me with an issue.
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The many versions of VPI arms that can use pivot damping fluid are very stable, and have no wobble.
I have heard the 3D arms, and they have nothing over a properly setup metal VPI arm, IMO!
The 3D arms look cheap!
The new second pivot "supposed improvement" is simply "expectation" bias - nothing to shoot out about.
stringreen is a long time VPI shill!
I like VPI, but I am not "mad" about all their newer products.
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"It has been experimentally shown that with such high pressures and
forces of friction between stylus and the vinyl, that the outer skin
layer of the record material melts as the tip slides over the plastic
and then refreezes almost as fast as it melted. It has been suggested
that since the melting temperature of vinyl is about 480 °F (248 °C)
that the same temperature exists in the contact area.”
Thank you again very much Raul for supplying the biggest laughs I am getting this week this claim is absolutely astoundingly extraordinary and it is obviously intended NOT to be taken seriously perhaps as a lesson that we should not believe everything we read or perhaps as a lesson that "fake news" is not a new phenomenon! It should be patently obvious to anyone with even a limited understanding of thermodynamics or who even knows how to operate a common household thermostat that a record does not go from room temperature to melting to freezing (!!!!) all in an instant simply because a stylus passes over it. While I suppose a conjecture could be made and it is only a conjecture that a stylus may heat a record due to friction but to suggest that it will melt the vinyl and then FREEZE It is beyond silly it is so funny thank you, Raul!
What would be really great is if we could capture those FREEZING temperatures and conduct them in such a way to offset the heat produced by our tube amplifiers! That would be great especially in the summer months Raul will you please use Google to see if that can be done and then cut and paste cut and paste and cut and paste and cut and paste
cut and paste and cut and paste and cut and paste and cut and paste some more and share that with us??? Thank you and thanks again for the big laughs you made my day your stuff gets funnier and funnier. |
My guess is the artistic director decided on substituting with a unipivot because it looked less boring than a gimballed one ;^)
Is it possible though, Raul, that even gimballed arms aren’t entirely "torsionally stable"? The movements may be small but real due to a necessary amount of bearing "play". I remember, decades ago, Syrinx used offset bearings to try to improve this and resonance behaviour. In fact I used to own a Syrinx PU2... ;^) Not surprisingly the LF performance really was something to write home about :) |
Dear @folkfreak : It's obvious that the tonearm in that you tube video is an unipivot design or a gimball one with a severe extreme bearing damages.
The video is a " dramatization " that helps to understand what is happening in continuious way at microscopic stylus tip during play of any cartridge in any unipivot tonearm design and in little lower way in quai-unipivot ones.
Forces are so huge that gravity alone can't correct it.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
Here's the link to the video in situ. http://www.marklevinson.com/productdetail/~/product/no515.html@moonglum may be correct as the video of the needle drop is of an Ortofon 2M Bronze (I think) whereas the 515 ships with (and is seen later in the video) with a Cadenza Bronze which looks quite different all in all this is coming off like amateur hour by Mark Levinson and VPI |
To avoid this argument gaining further momentum, perhaps someone in authority at Mark Levinson or VPI would care to address the Forum and explain what the "offending" frames in the video represent, if only as an exercise in damage limitation? ;^)
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I suspect what we may have witnessed in the video is an example of the "filmmaker's art". Just because Daniel Craig appears to jump off a bridge in 007 movie doesn't mean it is actually him doing the jumping! ;)
They may have inserted stock footage of a unipivot in action? People more familiar than I with the product range might be able to identify what's going on here more accurately? |
I agree that a cartridge must negotiate a very poor road to travel....in Arizona, some of the car roads are also very poor, yet my car suspension system compensates for that leaving a pleasant riding experience. My cartridge also has a suspension system.....I hear the music very well.
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That is creepy! I would have sworn that was a unipivot touching down. ;) |
@rauliruegas could you explain the problem you have with the video you posted and why this has any bearing to the merits of a unipivot design. As I see it the video shows the forces acting on a cartridge at needle drop, and speak more to a poorly damped lift/lower mechanism then anything else. Secondly the arm in the video is a gimballed design not a unipivot so the video has nothing to say about unipivot design. Anyway some more details on the issues you are trying to refer to would be helpful |
Dear friends: That " terrible earthwake " is unaceptable by any audio standards and that's is what happens with all unipivots or quai-unipivots.
A very well regarded tonearm unipivot with a tag over 25K states in its site:
"""
it is subjected to the mechanical vibrations from the musical source (the stylus moving in the groove), and it should before all not damage them and let them interfere with the electric signal coming from the cartridge. Each of the tonearm's constituents carries a crucial responsibility in the transmission of these vibrations, so every element, down to the smallest screw plays an essential role in the resulting sound. Those who claim that mechanical devices don’t have a sound don’t understand the nature of sound. Everything has a sound. Every piece of matter enters in vibration when it’s moving and that is what gives it its distinctive sound. """
seems to me that the tonearm designer of that company has very clear ( ? ) that critical subject and ( for me ) is just out of my mind why he choosed an unipivot design to fulfill that statement when it can't do it.
Btw, there is no single advantage in an unipivot design. What we listen through it are only higher distortions and that's all.
Cartridge needs " perfect " stability in a tonearm with NO earthwakes.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
Dear @moonglum : Great facts/information. As I said exist formidable audio information all over the net and comes from experts.
Facts that can makes a paramount differences in each one of us ignorance levels, obviously all of us can improve our knowledge levels, skills and tools !!
Btw, @dodgealum , you own the Levinson/VPI tonearm and in the " you tube " link I posted here we can see a way " terrible earthwake " down there that if it's happening then exist something really wrong in that tonearm design.
Would you comment about?, appreciated.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
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Dear Raul,
VDHs measurements of his own stylus seem to be defying the "natural order" of things by lowering the junction temperature to 60C. If true, one wonders if instead of vinyl reacting in a malleable way the stylus dislodges chunks which then fall into the groove causing further problems ;)
Of course 60C must presume perfect azimuth of his line contact(?) stylus. One would assume that misalignment would undoubtedly push the temp even higher than a perfectly aligned conical stylus's 140C, leaving the user in the same state as he was before :)
If VDH is successful with his low temp approach, the unit price of Last is going to rocket :D
Best regards
Bill
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Hi Raul, Found it. It is anecdotal but then most things on Forums are :) If you are in Windows, do a CTRL F and search "Coxybabe"....
https://forums.linn.co.uk/bb/archive/index.php?thread-29073.html All the best, Bill.
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Hi Raul,
I agree it is confusing. I recall looking up the data at the time and the "248C" figure was known to me. I was somewhat surprised back then but given how easily vinyl warps next to central heating radiators I dismissed 248C as one possible value depending on composition and state i.e temperature at which it becomes fully liquid as opposed to becoming "soft"?
Clearly it does need to be a lower figure than 248C in order for the melting/reforming thesis to work?
Now you've got me wondering again. :)
I'll try to find the reference for you ;)
Best regards,
Bill |
@moonglum : "
Van Den Hul states : "But the most important thing is record wear. I measured temperatures using a thermistor with a thin wire around the tip. A conical tip went up to about 140 deg C, but my one was 60 deg. I would like to come down further, but this was the lowest possible value."
R.
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Dear @moonglum : Handbook for enginners: "
"It has been experimentally shown that with such high pressures and forces of friction between stylus and the vinyl, that the outer skin layer of the record material melts as the tip slides over the plastic and then refreezes almost as fast as it melted. It has been suggested that since the melting temperature of vinyl is about 480 °F (248 °C) that the same temperature exists in the contact area.”
You can confirm here the fact you was thinking about and at the same time other additional fact that confirms about those very huge forces generated down there.
Btw, I can tell you that my very high ignorance levels brought me to a extreme high frustration levels. Never mind, such is life.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
Dear @dodgealum : This video is from the Levinson tonearm and I hope that what we see between the the second 10 and the 16 second is not what happens with that fixed bearing tonearm manufactured by VPI: https://www.youtube.com/watch?v=iTTLM9gPU9oAnyway, the video is a very good fact that confirm what that those huge forces makes with the cartridge/tonearm and why unipivots are out of question. Regards and enjoy the MUSIC NOT DISTORTIONS, R. |
Dear Raul,
Perhaps the moderator should step in at this point... ;)
Yes, I've only heard the SAT tone arm via 320kbps needle drops versus CDs etc but it presents a persuasive argument even if unattainable for the many. If there are hidden distortions in there I like them! ;) :)
BTW before I took early retirement, our thermal engineers constantly used thermal imaging cameras to analyse circuit boards and develop thermal maps. It's probably what VDH used to get an approximation of the stylus interface? They could be quite handy for troubleshooting too.
I recall an EMI chemist commenting on one forum that the melting point of some vinyl formulations was as low as 112C (I know, a bit nerve wracking for the steam cleaning brigade;)
Best regards,
Bill |
"If I remember the latest information about was by Dr. A:J Van denHul who measured 160° celcius between the stylus tip and groove"
This is another "funny fact" from Raul that is like his claim that VTF is "infinite" because the contact area of a stylus is "infinitely small" it sure must be a funny world Raul lives in with these "theories" that are "fantasies" that he insists are "facts." Such confusion about such basic things really makes me wonder whether Raul is aware of this confusion he loves to share as "facts" or whether Raul's problems are really much deeper than that in which case we should be feeling very sorry for Raul! |
Dear @moonglum : FS. is a great designer and I forgot his tonearm designs.
I experienced the Kuzma 4-point and is very good design and can understand why MF use it. In the other side: can any one justify against quality level performance a 28K on tag for a " simple " tonearm?
Well, maybe I don't know. Coming from a professional reviewer puts me ore doubts than certainty about.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
Indeed Raul, there's no substitute for a satisfied user endorsement :) It would be interesting to see a list of all designs that included a measure of compensation. VPI have now joined this club and you mentioned the Graham series. I believe Frank Schroeder has also had a try at defeating the "Achilles heel". Interestingly MF is no longer using a Cobra on his Continuum. Those duties are now shared between a 4-Point and the Swedish "SAT" tonearm ($28K - see here) : https://www.stereophile.com/content/swedish-analog-technologies-tonearm ....which must make it a contender for the most expensive on the market? Happy listening, Bill. |
Dear @moonglum : If I remember the latest information about was by Dr. A:J Van denHul who measured 160° celcius between the stylus tip and groove.
In the other side the best confirmation on the critical importance for tonearm true stability bearings to " avoid " all those huge developed forces are the listen experiences by @stringreen and @dodgealum whom owns the true unipivots and compared against the quasi-unipivot ( stringreen. ) and the gimballed one VPI model. Both very precise in the improvement levels.
That's the same experiences audiophiles had when changed from the original Graham tonearm ( similar design to the unipivot AC 3000. ) design to the Phantom ( I think you own this model. ) or from the DP-4 ( similar unipivot design to Highphonic. ) to de DP-6/8 or even the Cobra.
Good that after so long time some tonearm designers took in count the terrible unipivot disadvantage due to that unstability because this is what the cartridge does not needs and is not asking for. We always have to understand the cartridge needs at microscopic levels because almost all comes from there.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
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Actually, you’re right the gimbaled arm has virtues that the unipivot doesn’t and v/v. The reason the 2nd pivot attachment to the unipivot was released is because the 2nd pivot combines the advantages and none of the disadvantages to the competing designs....so said Harry.
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For those seeking a more "stable" platform for their cartridge that combines all the virtues of 3D construction (non-resonant, tonal purity) and unipivot design (extended treble, lots of inner detail) you may be interested in the new VPI 10" gimbaled arm that is a (superior) variant of the one that will appear on the Levinson table. I had a unipivot 3D-10 for about a year and it performed extremely well on my vintage Scout. I was able to work with Mat and Harry to outfit a "curvey" Scout plinth with their new gimbaled 3D-10 and can tell you that it has all the virtues of the unipivot but improves upon the bass response (deeper and tighter), imaging (tighter focus) and resolution (more inner detail and less distortion). The sound has that elusive combination of a relaxed presentation with extraordinary detail that I have heard in a few select top tier vinyl playback systems. I posted pictures on the VPI forum for those interested in taking a look.... http://www.vpiforum.com/viewtopic.php?f=11&t=9306 |
Dear Raul,
The report you published is the first I’ve seen that
confirms my long-held belief that diamonds “burn” more than they “wear”. Many
thanks for that! :)
The importance of the “message” rather than the messenger is
the main thing. People may differ on what they regard as the perfect analogue
medium or how to achieve it but it is gratifying that vinyl records are still
being celebrated today regardless of those differences.
Diverse solutions are also something to celebrate.
It shows that we’re still alive and thinking even if there
are downsides and compromises. :)
Best regards,
Bill
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Dear @moonglum : There are several audio subjects we are not totally aware of or that just we need to remember it.
Cartridge/tonearm/LP relationship is the most important subject in the analog experience.
Those very high forces generated in between puts its own " signature " on what we are listening.
It is not only that ( for me ) unipivots are forbidden tonearm designs but at almost the same critical importance is the tonearm necessity of been perfectly damped through its design or other way: forbidenn.
We have to remember that all those generated vibrations/resonances/errors between the LP/cartridge/tonearms continuously are generating feedback through that " circuit " adding complexity to the whole main subject.
Good that you had that " number " at the tonearm bearing.
Over the net exist " formidable " scientific information. AES/BAS are some sources about but I can see that in your country you already was aware of all those.
Regards and enjoy the MUSIC NOT DISTORTIONS,
R. |
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Raul thank you again I am still laughing away over you're logic that relies on the assumptions of "infinites" to arrive at real-world conclusions about tonearm pivots. To help you develop you're own arithmetic model rather than relying on the flawed work of others, here are some steps to follow.
After measuring the coefficient of friction as ratios between pivot points and accounting for the pivot-to-spindle difference as a variance on the ideal transference of rotational convergence, integrate the realtime consequence of the stylus to groove vibrational interaction with the cantilever assembly to arrive at a deviation (from the theoretical ideal, of course) of the frequency output seen at the phono preamp input while carefully accounting for the impedance and resistive effects that the cables themselves introduce to the ac signal. The resulting schemas can form the basis of the conclusion regarding the pivot friction forces that influence unipivot tonearms and this will help you synthesize extensible paradigms but please remember that the results you obtain will be limited to the specific example of tonearm that you have so carefully measured.
I do hope that you will share your results with this group so that we verify your calculations. |
"When this concentration of pressure upon the points of contact is calculated, we find it to be approximately 26 tons per square inch... The most interesting photos to me described the "infinite" amount of force applied to the groove by the spherical and elliptical stylus designs....Since the contact points are rounded, the contact area is infinitely small, so no matter what the tracking force, the tracking pressure at the point of contact is effectively infinite...At that point you have a hot stylus pressing infinitely hard against vinyl and this can easily create substantial softening (melting is not required, in fact melting is not the mechanism that creates the ripples)....because of the small area of contact that exists between the stylus tip and the groove, the pressure against the groove wall can rise up to many thousands of pounds per square inch."
Raul thank you so much for regurgitating this little piece of fantasy I had forgotten about it entirely you did a fine job with cut and paste cut and paste cut and paste. Of course it is wholly fantasy as it's faulty "logic" is based on "infinite" forces and a contact area that is "infinitely small" if you do not see the humor in this then something was lost in translation and perhaps you should read it again rather than just
cut and paste cut and paste cut and paste because of course in the real world of turntables used in Music Reproduction Systems there is no such thing as an infinite anything!
Also Raul if you are going to engage in cut and paste cut and paste cut and paste rather than going to the trouble of actually doing your own arithmetic then you should credit your sources and further when you cut and paste cut and paste cut and paste you might want to be a little less selective in your cut and paste cut and paste cut and paste and include disclaimer language such as one of your sources clearly noted at the top of its page that reprinted this "material": "Shure makes no claims as to the accuracy of the information in the text."
However I do thank you for supplying what I think will be the biggest laughs I get all week it is truly priceless what you have done here and I now realize that you probably really don't intend it to be taken seriously at all but are using a subtle form of sarcasm/humor to entertain us. Very very nice work but of course if I am mistaken about your motives then you will return to insult me as you have elsewhere in this thread under which circumstances I am quite confident that the moderators in their esteemed judgement will delete your remarks again as they have so many times previously regarding your commentary here.
Infinite! Funny! I track at about 2.1 grams what about you, Raul??? :) :) :) :)
:) :) :)
:) :) :)
:) :) :) *G* *G* *G* lol!!!
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You are most welcome, Raul.
I knew you were counting :) :)
Kind regards
Bill |
