Over the past 10 years, I have designed/rebuilt 3 different turntables. Prior to that I owned Rockport Capella II and Brinkmann Balanced turntables. Yet, in the quest for a great table, none of my efforts nor purchases have resulted in great pleasure.
So, I ask you to join me on this journey to theoretically technology for a world class, dare I say nearly perfect turntable. So, here are few thoughts:
Assumptions
1. cost no object
2. simplicity wins the day
3. tonearm and cartridge are not considered in this design
Goal
A. Constant speed
B. elimination of mechanical noise transmitted to stylus
When you think about it, a turntable really does 1 thing: spins an LP. Taking this a step further, spinning an LP at the proper speed. Taking this further further, spinning an LP at proper, constant speed. Finally, spinning an LP at proper, constant speed without mechanical/electrical noise transmitted to the stylus.
In today's world, nothing is perfect. So, turntable designers work to mitigate issues associated with constant speed, noise, etc. Damping, isolation, motors, bearings, plinths, etc. all are an attempt to mitigate the impact of root causes. So, why don't we attack the root cause issues and avoid the need for mitigation.
To this end, let's break this down into 2 basic functions:
1. platter speed accuracy, resolution and constancy
2. noise avoidance (mechanical or electrical)
Addressing the first item (speed). Depending upon which drive technology is used, we get different root causes. Take for example, idler drive. We know that idler wheels are not perfectly circular. Nor are the rims that interface with the idlers. At best, the rubber idler wheels likely are +/- 0.0005". Over time, the idler wheels wear/tear and the circularity is degraded. This leads to speed fluctuations, wow/flutter, etc. Belt technology is hamstrung by the belt itself. It flexes, stretches, wears, gets dirts, slips. This in itself leads to speed instability. Finally, direct drive. Theoretically, this appears to be the final frontier with one large assumption: sufficient motor control and drive technology. 50 years have passed since the advent of direct drive tables from the 1970s. And during this time, direct drive encoders, controllers, drives have all advanced to a point which we are able to create nano-technology solution that were not even a dream 50 years ago. So, maybe we should reconsider state-of-the-art direct drive rotary systems with sub-micron accuracy, resolution. Remember, cost no object and therefore, a direct drive rotary solution with ample control/drive would be state-of-the-art turntable drive capabilities, correct?
Secondly, noise. Once again, turntable manufacturers go thru hoops to remediate noise issues. Think about plinths, bearings (radial and thrust), platter, CLD, etc. What if we did not have mechanical noise at all? What if we relied upon state-of-the-art, world class air bearings used in the manufacturing and silicon wafer industries that have nano-precision, stability, stiffness? This is common technology that appears to be mostly overlooked by the audio community. Remember, cost no object. If we use an air bearing we have no, ziltch, nada, mechanical contact. Remember, our platter will float on a stiff airbearing, have no radial contact, no belt, no idler. Just a highest resolution, direct drive motor controlled with sub-micron accuracy, resolution.
Isn't this the final frontier based upon existing technology? Ultra precision direct drive with state-of-the-art air bearing. No need to worry about plinth, belts, idler wheels, etc. Just the platter floating on a stiff wafer of air spinning at highest precision, accuracy.
Here are some specification for the world class technology that we might apply to our theoretical ultimate turntable:
thrust bearing stiffness: 34N/um
Permissible torque in θx: 4.52 N·m
Moment of inertia in θZ, unloaded: 1780 kg·mm²
Drive torque clockwise in θZ: 0.86 N·m
Sensor signal: Sin/cos, 1 V peak-peak
Positioning accuracy in θZ: ± 8 µrad
Sensor resolution: 0.024 nm
The downside to this solution is that it is not simple. Air compressors, clean air purifiers add complexity while air bearings themselves are sensitive mechanical devices.
Yes, some manufacturers already use direct drive and air bearing technology. But are they using world class air bearings? World class direct drives? Please share your thoughts. Challenge the thinking and try to come up with alternative technology to surpass what is proposed.
Thanks!
So, I ask you to join me on this journey to theoretically technology for a world class, dare I say nearly perfect turntable. So, here are few thoughts:
Assumptions
1. cost no object
2. simplicity wins the day
3. tonearm and cartridge are not considered in this design
Goal
A. Constant speed
B. elimination of mechanical noise transmitted to stylus
When you think about it, a turntable really does 1 thing: spins an LP. Taking this a step further, spinning an LP at the proper speed. Taking this further further, spinning an LP at proper, constant speed. Finally, spinning an LP at proper, constant speed without mechanical/electrical noise transmitted to the stylus.
In today's world, nothing is perfect. So, turntable designers work to mitigate issues associated with constant speed, noise, etc. Damping, isolation, motors, bearings, plinths, etc. all are an attempt to mitigate the impact of root causes. So, why don't we attack the root cause issues and avoid the need for mitigation.
To this end, let's break this down into 2 basic functions:
1. platter speed accuracy, resolution and constancy
2. noise avoidance (mechanical or electrical)
Addressing the first item (speed). Depending upon which drive technology is used, we get different root causes. Take for example, idler drive. We know that idler wheels are not perfectly circular. Nor are the rims that interface with the idlers. At best, the rubber idler wheels likely are +/- 0.0005". Over time, the idler wheels wear/tear and the circularity is degraded. This leads to speed fluctuations, wow/flutter, etc. Belt technology is hamstrung by the belt itself. It flexes, stretches, wears, gets dirts, slips. This in itself leads to speed instability. Finally, direct drive. Theoretically, this appears to be the final frontier with one large assumption: sufficient motor control and drive technology. 50 years have passed since the advent of direct drive tables from the 1970s. And during this time, direct drive encoders, controllers, drives have all advanced to a point which we are able to create nano-technology solution that were not even a dream 50 years ago. So, maybe we should reconsider state-of-the-art direct drive rotary systems with sub-micron accuracy, resolution. Remember, cost no object and therefore, a direct drive rotary solution with ample control/drive would be state-of-the-art turntable drive capabilities, correct?
Secondly, noise. Once again, turntable manufacturers go thru hoops to remediate noise issues. Think about plinths, bearings (radial and thrust), platter, CLD, etc. What if we did not have mechanical noise at all? What if we relied upon state-of-the-art, world class air bearings used in the manufacturing and silicon wafer industries that have nano-precision, stability, stiffness? This is common technology that appears to be mostly overlooked by the audio community. Remember, cost no object. If we use an air bearing we have no, ziltch, nada, mechanical contact. Remember, our platter will float on a stiff airbearing, have no radial contact, no belt, no idler. Just a highest resolution, direct drive motor controlled with sub-micron accuracy, resolution.
Isn't this the final frontier based upon existing technology? Ultra precision direct drive with state-of-the-art air bearing. No need to worry about plinth, belts, idler wheels, etc. Just the platter floating on a stiff wafer of air spinning at highest precision, accuracy.
Here are some specification for the world class technology that we might apply to our theoretical ultimate turntable:
thrust bearing stiffness: 34N/um
Permissible torque in θx: 4.52 N·m
Moment of inertia in θZ, unloaded: 1780 kg·mm²
Drive torque clockwise in θZ: 0.86 N·m
Sensor signal: Sin/cos, 1 V peak-peak
Positioning accuracy in θZ: ± 8 µrad
Sensor resolution: 0.024 nm
The downside to this solution is that it is not simple. Air compressors, clean air purifiers add complexity while air bearings themselves are sensitive mechanical devices.
Yes, some manufacturers already use direct drive and air bearing technology. But are they using world class air bearings? World class direct drives? Please share your thoughts. Challenge the thinking and try to come up with alternative technology to surpass what is proposed.
Thanks!
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"stiff airbearing"
"stiff wafer of air"
Air is compressible AFAIK. (Think about air spring suspension in cars)
"stiff wafer of air"
Air is compressible AFAIK. (Think about air spring suspension in cars)
Airbearing stiffness is 34N/um. Once the air bearing is loaded with the platter, the vertical stiffness of the air bearing should be sufficient to counter any up/down forces caused by the tonearm/stylus. Also, IF the air bearing does have any vertical displacement, wouldn't the air bearing displacement be significantly less than the displacement caused by vibration with a conventional, mechanical thrust bearing?
Not likely, and both would have the typical unstable precession problem.
You might want to look into inverted bearings.
You might want to look into inverted bearings.
Is that a misprint? 2.4 x 10-11 meters? That's a factor of 20X better resolution than the smallest linewidth on Intel's newest integrated circuit . . . ??
HI,
Mag bearing I think are the simple good way for a silent bearing. Most if not all the mechanical noise comes from the thrust plate. Mag bearing do not have it. In addition is possible to use ceramic pivot to further reduce the friction and have the best possible allowance. I believe such bearing would not transmit noticeable noise to the stylus and make the bearing reliable and simple and more trouble free.
And perhaps they are already in the market. Clear Audio makes mag bearings.
Rgds
Adelmo
Mag bearing I think are the simple good way for a silent bearing. Most if not all the mechanical noise comes from the thrust plate. Mag bearing do not have it. In addition is possible to use ceramic pivot to further reduce the friction and have the best possible allowance. I believe such bearing would not transmit noticeable noise to the stylus and make the bearing reliable and simple and more trouble free.
And perhaps they are already in the market. Clear Audio makes mag bearings.
Rgds
Adelmo
Verdier have magnetic bearing turntable since 30 years ago.
La Platine VERDIER
The ancients lighthouse lantern floats over mercury bearing.
Regards
La Platine VERDIER
The ancients lighthouse lantern floats over mercury bearing.
Regards
Sensor resolution is 0.024 nm, see attachment for specs.
Attachments
You are overlooking an elephant in the room. What happens to the wow and flutter spec when you play a record that was pressed with an eccentricity of, say, 0.5mm on your state-of-the-art perfect speed turntable? Turntables already exist that can match the speed performance of the cutting lathes that your record was mastered on. To advance the state-of-the-art in playback turntables, how about addressing the root cause issue of off-center pressings with a design for an automatic centering device/mechanism?
Ray K
Well then, there's no excuse for not including it as standard equipment on a cost-is-no-object turntable project.
Ray K
Ray K
En mi opinión, todos los intentos de lograr un brazo tangencial que se aproxime ( ni hablar de igualar ) a un brazo lineal son sólo aproximaciones.
Hay miles de ejemplos Diy.
Creo que seria mejor dedicar semejante esfuerzo intelectual a tratar de acercarnos a un brazo lineal puramente mecanico con minimo arrastre ( fricción ) lateral.
Después de todo, el AS convencional deja mucho que dejar, aunque sea un giradiscos de alta tecnología.
Reemplazar los servo mecanismos por un sistema que tenga la minima fricción es el objetivo.
Creo que lograr un mecanismo en el cual la aguje se deslize igual que la aguja de corte, con el minimo desgaste , es un objetivo mas redituable a nivel satisfacción personal y quizás mas sencillo......
Que tal un poco de Molikote ( Disulfuro de Molibdeno ) diluiído sobre una superficie de teflón ?
PTFE posee el más bajo coeficiente de fricción de todos los
materiales sólidos; los valores varían entre 0.05 a 0.09: Los coeficientes
de fricción estático y dinámico son casi iguales, por lo tanto casi no
existe el efecto comúnmente denominado stick-slip, o sea que no se
produce el efecto como de leve pegado cuando se desea que una pieza
pase del estado de reposo al de movimiento. Cuando se incrementa la
carga, el coeficiente de fricción decrece antes de alcanzar un valor
constante. El coeficiente de fricción aumenta al aumentar la velocidad. El
coeficiente de fricción permanece constante al variar la temperatura.
Desgaste: El desgaste depende de las condiciones de la superficie de
deslizamiento y obviamente de la velocidad y la carga aplicada a dicha
superficie. El desgaste se reduce considerablemente cuando se agrega
al PTFE adecuados materiales en diferentes proporciones (carbón ,
vidrio , grafito , etc.).
http://www.coplastic.es/resources/uploads/Documentos/34646203.pdf
Hay miles de ejemplos Diy.
Creo que seria mejor dedicar semejante esfuerzo intelectual a tratar de acercarnos a un brazo lineal puramente mecanico con minimo arrastre ( fricción ) lateral.
Después de todo, el AS convencional deja mucho que dejar, aunque sea un giradiscos de alta tecnología.
Reemplazar los servo mecanismos por un sistema que tenga la minima fricción es el objetivo.
Creo que lograr un mecanismo en el cual la aguje se deslize igual que la aguja de corte, con el minimo desgaste , es un objetivo mas redituable a nivel satisfacción personal y quizás mas sencillo......
Que tal un poco de Molikote ( Disulfuro de Molibdeno ) diluiído sobre una superficie de teflón ?
PTFE posee el más bajo coeficiente de fricción de todos los
materiales sólidos; los valores varían entre 0.05 a 0.09: Los coeficientes
de fricción estático y dinámico son casi iguales, por lo tanto casi no
existe el efecto comúnmente denominado stick-slip, o sea que no se
produce el efecto como de leve pegado cuando se desea que una pieza
pase del estado de reposo al de movimiento. Cuando se incrementa la
carga, el coeficiente de fricción decrece antes de alcanzar un valor
constante. El coeficiente de fricción aumenta al aumentar la velocidad. El
coeficiente de fricción permanece constante al variar la temperatura.
Desgaste: El desgaste depende de las condiciones de la superficie de
deslizamiento y obviamente de la velocidad y la carga aplicada a dicha
superficie. El desgaste se reduce considerablemente cuando se agrega
al PTFE adecuados materiales en diferentes proporciones (carbón ,
vidrio , grafito , etc.).
http://www.coplastic.es/resources/uploads/Documentos/34646203.pdf
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I only have some off-center records because they were played on elementary turntables with the center axis too large ( pindle ), and forcibly put in and out, enlarging the same accordingly. Those vinyls were inherited.
If I ever bought a new off-center vinyl, I returned it immediately, I am glad I did not find out about this technological marvel, I have saved some good money ..
😀
tx1000
It's hilarious to start a topic with the word "ultimate" then make a case for air bearings that need an ultimate air pump...Now...if i share my thoughts on this...do i need an NDO signed by everyone here 🙂 ? There is a neat solution invented in 1905 i didn't see used in any turntable for a very good reason and that is because Neumann vinyl cutter lathe is using normal ball bearings and metal platter for a reason while the best air bearing is not using any air pump for more than 100 years, but it's so damn difficult to build such things without special machinery that "cost no object"means become objectionable stupid costs goals...
The reason we use :ultimate" word more often today is because we envy some little liars that were able to fool the entire world "reinventing" the seventies and selling it for hundreds of thousands of dollars in the last decade while using the lowest technology, even lower than the one used in the 70's. If you don't believe me...open a russian wrist watch made back then and ignore the ten times more precise swiss watches until you get what you missed. Air bearing and fantastically precise direct drive motors were already in use in the 70's, manufactured in 0.5 micron presicion range and used in turntables valued at less than 3...500 dollars(1000 in todays money)?Well I know at least three commercial well known brands doing it up until the early 80's, but because nobody ever said anything about it on www i will keep the silence myself enjoying the posibility of still buying such a turntable with less than 200 dollars and let you dream of thousands of dollars Clearaudio BS remarketed as "ultimate" whatever using ceramic bearings that can't conduct any static electricity...In the 70's there were turntables manufactured with 10 times higher precision than any turntable made today in any price range...
You can buy air bearings able to keep afloat a thousand ton motors if you have the right money, but why would you do it? Do you really need platters that cannot conduct static electricity at all ? You'd better have some metal in contact with your platter, you need conductive mat so no cork and you need actually to get same precision as a Neumann lathe using regular ball bearings and three phase motors , right? Well folks that's already been done 40 years ago. When the downs of a technology overcome the ups it's better to reevaluate your goals and make use of the right means...
The Self-Levitating Kingsbury Aerodynamic Bearing - YouTube
Tilting Pad Bearings for Hydrodynamic, Fluid-Film Applications
For anyone trying to make the case for a completely airborn platter i'd say better look at the picture of a VHS video drum holding the recording heads and try figure out what's the elephant is the room when assessing useful turntable technology.
The reason we use :ultimate" word more often today is because we envy some little liars that were able to fool the entire world "reinventing" the seventies and selling it for hundreds of thousands of dollars in the last decade while using the lowest technology, even lower than the one used in the 70's. If you don't believe me...open a russian wrist watch made back then and ignore the ten times more precise swiss watches until you get what you missed. Air bearing and fantastically precise direct drive motors were already in use in the 70's, manufactured in 0.5 micron presicion range and used in turntables valued at less than 3...500 dollars(1000 in todays money)?Well I know at least three commercial well known brands doing it up until the early 80's, but because nobody ever said anything about it on www i will keep the silence myself enjoying the posibility of still buying such a turntable with less than 200 dollars and let you dream of thousands of dollars Clearaudio BS remarketed as "ultimate" whatever using ceramic bearings that can't conduct any static electricity...In the 70's there were turntables manufactured with 10 times higher precision than any turntable made today in any price range...
You can buy air bearings able to keep afloat a thousand ton motors if you have the right money, but why would you do it? Do you really need platters that cannot conduct static electricity at all ? You'd better have some metal in contact with your platter, you need conductive mat so no cork and you need actually to get same precision as a Neumann lathe using regular ball bearings and three phase motors , right? Well folks that's already been done 40 years ago. When the downs of a technology overcome the ups it's better to reevaluate your goals and make use of the right means...
The Self-Levitating Kingsbury Aerodynamic Bearing - YouTube
Tilting Pad Bearings for Hydrodynamic, Fluid-Film Applications
For anyone trying to make the case for a completely airborn platter i'd say better look at the picture of a VHS video drum holding the recording heads and try figure out what's the elephant is the room when assessing useful turntable technology.
Attachments
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I have spent a good deal of time modifying a Technics SP10mk2 so I find this thread interesting.
Here are some of my thoughts and experience. Vibration energy generated by the stylus / LP interface and other erroneous vibrations are what ALL of the top TT manufactures spend most of their R&D on, improving this area has a massive impact on the micro detail a TT can retrieve. Rigidity is also another key factor.
If you were able to remove ALL erroneous vibration what would the TT sound like, my guess is the best in the world. The Nakamichi while a technological marvel is not the greatest sounding TT, it's been a long time since I heard one but it wasn't as good as the Marantz TT1000.
Air bearing TT's have a one major issue, no grounding of the vibration energy imparted into the platter/spindle. With the volume turned all the way down put a stethoscope on the bearing while playing an LP and see how much energy is there, you will be surprised if you have never done this before. If there is no path for this energy to be damped by a good plinth it will be reflected back to the cartridge.
Air bearings if they are stiff will transmit vibrations across their boundary. Remember we are dealing with modulation in the groove as small as 0.1micron and a good TT will reproduce this.
I agree with the DD motor and there a loads of good vintage DD's that can be used as a platform to build an ultimate TT. This is my goal with my SP10. I have been experimenting with platters and have made units from 5 to 11kg and the best sounding platter was 7kg but IMO the improvement was due to the thickness of the POM (Acetal) rather than mass.
Here are some of my thoughts and experience. Vibration energy generated by the stylus / LP interface and other erroneous vibrations are what ALL of the top TT manufactures spend most of their R&D on, improving this area has a massive impact on the micro detail a TT can retrieve. Rigidity is also another key factor.
If you were able to remove ALL erroneous vibration what would the TT sound like, my guess is the best in the world. The Nakamichi while a technological marvel is not the greatest sounding TT, it's been a long time since I heard one but it wasn't as good as the Marantz TT1000.
Air bearing TT's have a one major issue, no grounding of the vibration energy imparted into the platter/spindle. With the volume turned all the way down put a stethoscope on the bearing while playing an LP and see how much energy is there, you will be surprised if you have never done this before. If there is no path for this energy to be damped by a good plinth it will be reflected back to the cartridge.
Air bearings if they are stiff will transmit vibrations across their boundary. Remember we are dealing with modulation in the groove as small as 0.1micron and a good TT will reproduce this.
I agree with the DD motor and there a loads of good vintage DD's that can be used as a platform to build an ultimate TT. This is my goal with my SP10. I have been experimenting with platters and have made units from 5 to 11kg and the best sounding platter was 7kg but IMO the improvement was due to the thickness of the POM (Acetal) rather than mass.
Real engineering is not made to adress all the problems separately in the bet posible way , but making a synthesis that can adress all the problems at once with minimum effort.
From a purely technical point of view a frictionless system is a pure nightmare to deal with and actually the spindle or motor friction plays the same role as a resistor in a resonant circuit...it breaks the resonance.
In a turntable there's the case of mechanical resonance , how much energy do you deliver to the platter , how much of it is absorbed by the moving platter system friction and what percentage of it is the friction of the stylus rubbing against the vinyl record.
A direct drive system is adresing it from a more pure electrical anti-resonant standpoint than all the others.
If i'd be to consider the best driving system , most probably there would be two of them:
1. a Dual EDS-1000 motor with the least amount of feedback and you can find it what it means when touching the 3.4kg platter with the least amount of force
2.a regular capstan motor found in any VHS player that's able to keep a very steady and low speed whyle dealing with a lot of friction using a very tight and complex feedback system that's still based on the DUAL EDS-1000 principles.
When the turntable industry relaunched 13 years ago it started with a belt drive heavy platter turntable who's platter you'd need to start turning it by hand as the platter was too heavy for the motor to have it started by itself...It enunciated the same principles found in Dual EDS-1000 except it used the lowest technology possible...
Yet the best technology is not always perceived as the best in audio , actually it's the opposite , that is why a Dual 1219 idler turntable is valued and it's not because of the idler itself, but it's because of its very powerful synchronous motor that feels all the mains frequency fluctuations transmiting them instantly to the platter.Those sudden phase shift and frequency variations you normally get in a mains electrification system are translated in sudden platter speed variations that give the idlers sound which we actually like cause it has the same result as the Attack function on an analog synthesizer or when pinchhing a guitar string with more force and that we like a lot, while it's not the same as the usual tape wow and flutter because the rate of speed change or speed slew rate is higher in mains than in your usual belt drive cassette player.
I for one ...i like all properly built idlers, belt or direct drive and i had some of all the best versions you can get in idlers, belt drivc and direct drive...There's really no point in trying to build "the best" turntable.There's no such thing and never will be.
From a purely technical point of view a frictionless system is a pure nightmare to deal with and actually the spindle or motor friction plays the same role as a resistor in a resonant circuit...it breaks the resonance.
In a turntable there's the case of mechanical resonance , how much energy do you deliver to the platter , how much of it is absorbed by the moving platter system friction and what percentage of it is the friction of the stylus rubbing against the vinyl record.
A direct drive system is adresing it from a more pure electrical anti-resonant standpoint than all the others.
If i'd be to consider the best driving system , most probably there would be two of them:
1. a Dual EDS-1000 motor with the least amount of feedback and you can find it what it means when touching the 3.4kg platter with the least amount of force
2.a regular capstan motor found in any VHS player that's able to keep a very steady and low speed whyle dealing with a lot of friction using a very tight and complex feedback system that's still based on the DUAL EDS-1000 principles.
When the turntable industry relaunched 13 years ago it started with a belt drive heavy platter turntable who's platter you'd need to start turning it by hand as the platter was too heavy for the motor to have it started by itself...It enunciated the same principles found in Dual EDS-1000 except it used the lowest technology possible...
Yet the best technology is not always perceived as the best in audio , actually it's the opposite , that is why a Dual 1219 idler turntable is valued and it's not because of the idler itself, but it's because of its very powerful synchronous motor that feels all the mains frequency fluctuations transmiting them instantly to the platter.Those sudden phase shift and frequency variations you normally get in a mains electrification system are translated in sudden platter speed variations that give the idlers sound which we actually like cause it has the same result as the Attack function on an analog synthesizer or when pinchhing a guitar string with more force and that we like a lot, while it's not the same as the usual tape wow and flutter because the rate of speed change or speed slew rate is higher in mains than in your usual belt drive cassette player.
I for one ...i like all properly built idlers, belt or direct drive and i had some of all the best versions you can get in idlers, belt drivc and direct drive...There's really no point in trying to build "the best" turntable.There's no such thing and never will be.
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@warrjon
Actually the SP10mk2 motor is really low quality and i know two brands using way better direct drive motors in the 70's just lower quality discrete driving electronics.
Actually the SP10mk2 motor is really low quality and i know two brands using way better direct drive motors in the 70's just lower quality discrete driving electronics.
decouple the spindle
Since we are talking about the "ultimate," I would start with NOT making the bearing shaft and spindle machined as one piece so the bearing noise would not be transmitted to the spindle that touches the vinyl. That would be a good start.
Since we are talking about the "ultimate," I would start with NOT making the bearing shaft and spindle machined as one piece so the bearing noise would not be transmitted to the spindle that touches the vinyl. That would be a good start.