Is an air bearing for a platter really a good thing?

MrC.

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Feb 16, 2019
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With the researgence of air bearing turntables by Techdas and now Kuzma, I wonder if an air bearing for a TT platter is really a plus. I am not talking about possibilities of air puffing from the pump translating to the bearing, though unless properly accounted for and filtered that can be an issue as well. I think there is a greater issue regarding the motor platter interface and the effect of friction on the motor output and torque curve. The needle may have a negligible effect on the platter speed but if the motor is already fighting friction and applying torque, like in the Garrard grease bearing or the Thorens TD-124 eddy brake, it is already putting out more grunt to plough through the viscosity of the grease or brake so the needle drag is nothing in comparison. I suppose the addition of mass to the platter makes a difference in the inertia of the platter to make up for the lower torque of the motor and lack of motor output based on a low friction system, but I recall reading somewhere that the three motor scheme of the AN turntable put out equivalent rotational torque to a platter weighing a quarter of a ton.

I believe J.C. Verdier wrote his own opinions that friction was a good thing as it required this extra output by the motor and all of his turntables, even his nouvelle platine, have an oil bearing even though it uses magnets to lower but not suspend the weight of the platter. Zero friction can cause the motor and platter to be effected by the stylus drag and in the case of low mass platters as used on the old DD tables, may cause a hunting for the correct speed in a reactive feedback loop from the speed servo, which caused some to walk away from DD drives, although I have found the best ones to have serious sonic plusses. It may have been for this reason that the old Micro Seiki introduced the flywheels that were accessories to its large air suspended tables, where the flywheel became a non suspended drag on the platter turned by an auxiliary belt around the platter. The flywheel would have caused the motor to put out more torque to turn the system on a constant basis causing less sensitivity to the drag of the stylus. Its just a thought but I have never lived with an air suspended table to make a direct comparison.
 

cjfrbw

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There is the issue of an air suspended platter leaving no drainage point for unwanted vibrations i.e. they can ring in the platter and go back to the needle. I think that is why the manufacturers of the original Caliburn turntable kept one degree of physical bearing contact even with levitation after they ran computer simulations and made laser measurements.
 

BlueFox

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The real question is “a platter really a good thing.” :)
 

microstrip

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Speaking of air (and all that goes with it), I'm more sceptical of vacuum hold-down.

I also was until I tried it on the Tech AirForce One. Now I can't play an LP without switching it on.
 

bonzo75

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Speaking of air (and all that goes with it), I'm more sceptical of vacuum hold-down.

Works great in Vyger and the micro Seiki bl111, a version of which has the vacuum hold down
 
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bonzo75

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Also, clamps / weights play a role where there is no suspension and no vacuum hold down. With vacuum on, there is almost no benefit, implies latter is having some benefit
 
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ddk

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With the researgence of air bearing turntables by Techdas and now Kuzma, I wonder if an air bearing for a TT platter is really a plus. I am not talking about possibilities of air puffing from the pump translating to the bearing, though unless properly accounted for and filtered that can be an issue as well. I think there is a greater issue regarding the motor platter interface and the effect of friction on the motor output and torque curve. The needle may have a negligible effect on the platter speed but if the motor is already fighting friction and applying torque, like in the Garrard grease bearing or the Thorens TD-124 eddy brake, it is already putting out more grunt to plough through the viscosity of the grease or brake so the needle drag is nothing in comparison. I suppose the addition of mass to the platter makes a difference in the inertia of the platter to make up for the lower torque of the motor and lack of motor output based on a low friction system, but I recall reading somewhere that the three motor scheme of the AN turntable put out equivalent rotational torque to a platter weighing a quarter of a ton.

I believe J.C. Verdier wrote his own opinions that friction was a good thing as it required this extra output by the motor and all of his turntables, even his nouvelle platine, have an oil bearing even though it uses magnets to lower but not suspend the weight of the platter. Zero friction can cause the motor and platter to be effected by the stylus drag and in the case of low mass platters as used on the old DD tables, may cause a hunting for the correct speed in a reactive feedback loop from the speed servo, which caused some to walk away from DD drives, although I have found the best ones to have serious sonic plusses. It may have been for this reason that the old Micro Seiki introduced the flywheels that were accessories to its large air suspended tables, where the flywheel became a non suspended drag on the platter turned by an auxiliary belt around the platter. The flywheel would have caused the motor to put out more torque to turn the system on a constant basis causing less sensitivity to the drag of the stylus. Its just a thought but I have never lived with an air suspended table to make a direct comparison.

You can’t generalize in this way, high quality turntables are a lot more complex to design and manufacture than most people realize with many variables that have a direct affect on the sound. How do you isolate the contribution of the bearing type to the overall sound from all the other decisions made by the designer to achieve that sound for that price without going through ground up testing and eliminating all variables? There are excellent examples of air, oil and hybrid designs out there, it’s all in the execution.

david
 
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Ron Resnick

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Tim,

I ran post #7 through Google Translate, Kedar Edition, and received an error message.
 

microstrip

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Are there disadvantages to playing a record on the AF1 w/out vacuum on? Will it accept a clamp or weight?

We can play with or without vacuum - it is just a sound preference. The system can be switched on and off during playback, it takes just a few seconds to release the LP.

The suction system is very interesting - it uses moderate vacuum during the first seconds to seal the record and then just a minimum suction to keep it in contact with the mat.

Unfortunately it can accept the clamp, even with suction - it sounds significantly better with the extremely heavy tungsten clamp, I had to get it. ;)
 
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microstrip

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There is the issue of an air suspended platter leaving no drainage point for unwanted vibrations i.e. they can ring in the platter and go back to the needle. I think that is why the manufacturers of the original Caliburn turntable kept one degree of physical bearing contact even with levitation after they ran computer simulations and made laser measurements.

As far as I have read air bearings can pass vibrations - compressed air in very thin films has different properties than atmospheric air in large volumes. The purpose of the air bearing is getting very low friction and noise, not sound isolation.
 

MrC.

New Member
Feb 16, 2019
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12
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You can’t generalize in this way, high quality turntables are a lot more complex to design and manufacture than most people realize with many variables that have a direct affect on the sound. How do you isolate the contribution of the bearing type to the overall sound from all the other decisions made by the designer to achieve that sound for that price without going through ground up testing and eliminating all variables? There are excellent examples of air, oil and hybrid designs out there, it’s all in the execution.

david
This is undoubtedly a fair statement and I have had my preconceptions about turntable designs tossed in the dustbin after hearing a turntable I lusted for bested by a cheaper deck playing through the same system. What I’m getting at is why something sounds better and whether things we think of as detractors, like friction in the bearing or rotational resistance added after the fact, as in an eddy brake, have a beneficial effect that accounts for why someone may prefer a grease bearing Garrard or td124 to many expensive modern decks.
 

JackD201

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Speaking of air (and all that goes with it), I'm more sceptical of vacuum hold-down.
Hi Tim

I was too growing up with vacuum Luxmans. The latter vacuums that take are from the rims and better calibrated suction dealt with potential damage to the LPs. They also do some things more than just flatten out warpage. We know there was all the buzz about heavy vinyl. Ooooh 200 grams! :D Well, while many releases turned out to be noisy busts, the good ones showed potential even if they were a hassle to calibrate VTA for for a guy like me who lives on a staple of 150g discs. In any case, when properly implemented, the vacuum seals spread out (no play thus o weird damping sound) and the record is coupled to the platter. In the AF1 case you could say you've now got a 30,000g LP or roughly the weight of a Lamm M1.2 Reference. The question of vibration particularly those audible from the deep bass up to the midrange remains. With TechDAS this is dealt with by providing an internal drain in the form of vacuum chambers within the platter. The chambers also allow weight distribution of the platter towards the outside rim for better inertia. The platters are tested on the same machines used for wheel balancing and are tested at high speed to ensure stability. So, no worries about drag and no worries about energy grounding. The result is quick, tuneful and solid bass.

The question is.....is this what one wants? In my case yes, for others no. Many have become accustomed to what they have come to love as LP's "warmth". As we know now this is a product of desirable resonances. In some cases they behave as a form of noise shaping but mostly they just add a layer of texture that, well, sounds good. It sounds good I believe because humans in the wild are bombarded with a layer of noise every second of the day.

Here is where it gets fascinating to me mainly because I am a record collector first and audiophile second. If it were the other way around, I would get an AF3P instead of the 1 or 1P. The platter has less mass, one chamber less and no suspension. It is very much "warmer" aka less damped. For the Porsche guys think GTS vs GT2RS. Daily driver that can still kick ass.

Some members like Khun Tang have described the sound of their 1s as too intense. The damping contributes to this by sapping away resonances but so does the flattening of the disc. Perimeter rings will display this somewhat but these are on full display with 1s. The only other example I have come across is the Teragakii tables of dumbell heavy clamp and concave platter fame. As you of course know but those not interested in the mechanics may not is that there is very low potential energy within a cartridge as the coil and magnets interact to create that electrical signal. Any spurious energy resulting from unwanted motion eats up that energy and compresses the signal as headroom drops. This is why we pay so much attention to Azimuth on the horizontal plane but what about the vertical? Vertical movement and horizontal movement are inseperable the cart will move in arcs and waves. The stylus is in effect on a surface B road. Flattening the disc turns that road into freshly laid asphalt, all the better to use the potential output voltage of our carts. Too intense? In many contexts, yes sure. For me, I get at least in my mind more of what is on the LP and cart and less of the sound of the table and arm. This works out well for me and others of the same mindset. When I want romance I go with Koetsus and my CA, Lyra, MYSonic, Airtight and TD Carts I use when I want more obvious detail via deeper contrast as opposed to color saturation. Funny enough the dichotomy makes two arms enough for me.

Those with airbearings but no hold down/vacuum chambers are not lost in the dumps by a long shot. It may ot be as intense but here choice and combination of clamp and mats help one achieve the type and amount of damping desired albeit not the balls to the wall dynnamics which is perhaps ot desirable anyway making it a total non issue.

At the end of the day, we should all go with what we like :)
 
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tima

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We can play with or without vacuum - it is just a sound preference. The system can be switched on and off during playback, it takes just a few seconds to release the LP.

The suction system is very interesting - it uses moderate vacuum during the first seconds to seal the record and then just a minimum suction to keep it in contact with the mat.

Unfortunately it can accept the clamp, even with suction - it sounds significantly better with the extremely heavy tungsten clamp, I had to get it. ;)

Thanks. My understanding from proponents of - what should I call it - tight(er) coupling between a record and the platter is that tighter coupling reduces (?) resonance in the vinyl record or mitigates resonance transference or generation in the vinyl record. And the reduction or vinyl resonance is desirable because less of it transfers to or negatively affects the stylus traveling the groove. Or something like that.

I haven't read Jack's downstream post yet so maybe the answer is there, but is the above understanding reasonable/accurate about why we might consider doing something to more tightly couple the record to the platter? Are there other reasons?

Presumably different tables offer ways of tighter record-to-platter coupling that are tied to their design. The AF1 and others offer vacuum mechanisms of varying design. My Monaco 2 table is designed for use with its screw down clamp system involving a platter with a damping coat, sorbothane washers of 3 different durometers (for different record thickness), and the clamp that goes to a specific hold-down force.

Then there are tables without hold-down as part of their design or are agnostic to it. And there is an active after-market for clamps of all sorts.

I'm guessing the vacuum designers and advocates argue that vacuum provides a more even or consistent hold-down of the record across its surface. Or some may just say "it's part of the table's design."

I speculate that In the end (?) tighter coupling is thought to be a means of reducing distortion. AND, the removal or reduction of such distortion is audible in a positive way. Iow, tighter coupling yields better sound - whatever that means to the individual listener. AND, such distortion reduction overcomes any possible downside from any noise introduced by a vacuum mechanism, and any possible mechanical finickyness, though I understand the more sophisticated vacuum mechansims (such as your AF-1) intend to reduce that noise.

I suppose my scepticism comes down to: a) does tighter coupling yield better sound and b) best I can tell vacuum hold-down (or an in-built clamping system) does drive up table cost, so where is the increased purchase cost and maintenance overhead relative to actual benefit. I assume those who have tables with vacuum hold-down find it worthy. If the table supports it I assume one would use it, but since it's part of the table's design, not doing so would be using the table outside its design parameters so a bit of catch-22.

Let me say my scepticism does not mean rejection of tighter coupling. Thanks for reading.
 
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tima

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...there is very low potential energy within a cartridge as the coil and magnets interact to create that electrical signal. Any spurious energy resulting from unwanted motion eats up that energy and compresses the signal as headroom drops. This is why we pay so much attention to Azimuth on the horizontal plane but what about the vertical? Vertical movement and horizontal movement are inseperable the cart will move in arcs and waves. The stylus is in effect on a surface B road. Flattening the disc turns that road into freshly laid asphalt, all the better to use the potential output voltage of our carts. Too intense? In many contexts, yes sure. For me, I get at least in my mind more of what is on the LP and cart and less of the sound of the table and arm. ...

An absolutely wonderful post, Jack - thank you. It helps me think more clearly on the subject of record hold-down. I was not looking closely at the 'cartridge spring effect' of a less than perfectly flat record. I remember (now) the early SOTA vacuum table claims were based more on eliminating warp than resonance.
 

JackD201

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Thank you too Tim :)
 

ddk

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May 19, 2013
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Speaking of air (and all that goes with it), I'm more sceptical of vacuum hold-down.
It's just a feature Tim and having it or not doesn't make or break a turntable. There are a lot of people who preferred the solid platter option with the Micro Seiki's too, personally I'm agnostic and it comes down to user preference.
An absolutely wonderful post, Jack - thank you. It helps me think more clearly on the subject of record hold-down. I was not looking closely at the 'cartridge spring effect' of a less than perfectly flat record. I remember (now) the early SOTA vacuum table claims were based more on eliminating warp than resonance.

That's because they didn't design it to dampen resonance. All vacuum hold down systems aren't created equal nor do they serve the same purpose. We can debate the value of vacuum hold down vs other methods for coupling and flattening of records but in MS and TechDas turntables vacuum hold isn't just for that purpose it's an integral part of their platter design. They have a two piece design with a relatively large cavity and use air to dampen and tune the platter that's why listening with vacuum on is preferred by most including myself with those turntables. This is air tuning and with the AF1 they've taken the concept further into all aspects of the design where air (because it has a sound quality like any other material) and air pressure is used to dampen the system and tune the final sound, hence the name. Best to look at other turntables if you're simply trying to figure out the validity of vacuum versus other coupling methods including use of a flexible platters to achieve flattening and coupling.

david
 

tima

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Mar 4, 2014
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This is air tuning and with the AF1 they've taken the concept further into all aspects of the design where air (because it has a sound quality like any other material) and air pressure is used to dampen the system and tune the final sound, hence the name. Best to look at other turntables if you're simply trying to figure out the validity of vacuum versus other coupling methods ...

Thanks David, now I better understand your earlier summation: " high quality turntables are a lot more complex to design and manufacture than most people realize with many variables that have a direct affect on the sound."
 

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