Direct Drive vs. Idler Drive vs. Belt drive


I'd like to know your thoughts on the strengths and weaknesses of each drive system. I can see that direct drive is more in vogue over the last few years but is it superior to the other drive systems? I've had first-hand experiences with two out of the three drive systems but looking to learn more.
128x128scar972
@ferrari275 i think you’re quoting me, not neonknight :)

But you’re right, the idea is sandwich of materials(to block EMI effect if there is any or that none existing noise from the bearing that every DD hater mentioning here), not just heavy platter made from one material. Do you know anyone who keep using rubber mat on Technics ? I do not own SP10R, but i owned SP 10 mkII and Micro Seiki CU-500 mat is a perfect match, the platter of SP-10R is flat and slightly different on the edge. Brass alloy is cheaper than gunmetal. Copper is cheaper than gunmetal too, but this copper matt from artisan fidelity looks very nice.
neonknight

"Even if the platter replaced with thicker and heavier one those guys always add copper mat on top of it, just like the latest Technics SP-10R."

The Technics Sp10R's main platter was designed to be used in combination with a platter mat, like the supplied factory rubber mat or an aftermarket metal based mat (ie. Copper, gunmetal, stainless steel, delrin ect.)
As shown in the poster link, that Sp10R platter was photographed in the "nude" without a mat installed.  The material section at the top is a brass alloy, and not Copper. 
Dear Halcro,
I still love my belt driven tables. As I am „walking“ from one to the other I recently found out that the two mentioned favorites attract me most. Nevertheless the AS equipped Brinkmann Anniversary  and the Victor are very close to the Denon. I regard the big motor of the Denon, the 4cm aluminum chassis as well as the platter (which I improved by a 1000 USD ceramic overlay) running by the new Furutech connectors as very stable and quiet. The AS cartridge is a good match.

Caeles II, the Micro and the Continuum are not far away as well.

best
E.


Sdrsdrsdr,

I am using the Ortofon 309, also with a heavy weight for taking up the Neumanns. And the SME 3012 (I), first version.
Dover,
I am using the original Active Dynamic Servo Tracer with two interchangeable wands,  medium weight in S-shape and low weight in straight shape. It is a kind of Sony Biotracer Arm but really good!
I also use the SME 3012R and the ToXiom.


@thuchan 
I am curious to what tonearms you have tried on the Denon DP100.
Could you please enlighten us.
I use a constrained layer solution on my SP10 MK2  a K-Works ERSA mat made of ERS paper on the plater next is a OEM 1/8 rubber mat and under the record is a Boston Mat 2 all clamped by a Michell clamp . 
Hi Thuchan,
Thanks for giving us this 'current' appraisal of your turntable preferences...😃
As you are a long time connoisseur (and user) of all turntable types....it is valuable for us to hear your experiences.
I must admit I'm slightly surprised that a belt-drive turntable is not amongst your current favourites as you've been a long-time fan of that technology starting with the SOTA big Micro-Seikis....
You also have the SOTA full Air-Bearing Caeles II which is at the forefront of belt-drive technology like the TechDas Airforce Zero....

It would be interesting to hear your impressions of the differences you find in the vintage DD Japanese turntables like the Denon DP-100M and Victor TT-101 compared to the modern Brinkmann Oasis..?

Regards
Hi,
I am using three DDs: Victor 101, Denon DP-100M, Brinkmann Oasis 10th Anniversary. My running belt driven tables are: Continuum Criterion, Micro Seiki SX 8000 double platter and Caeles II. The idler table is an EMT R-80 (Prototyp of 927).

all units are in a state of art condition wearing excellent tonearms and carts (AudioCirc).

you may now ask me what is the best sounding table?Of course all have a specific sound and character. I am playing them all but my favorite at the moment are two vintage designs: the Denon DP-100M and the EMT R-80.

best
@ mijostyn

Well the table that gets the most hours currently is the Brinkmann with Audiomods Series Six arm, which I use for more casual listening. This is primarily based on the Ortofon A90, which is the cartridge I have that I am most willing to use up the hours on, and is probably the easiest to retip. My cartridge collection is small, I have a ZYX 4D and a Denon DL-S1 that I can also use on the table. 

When I sit down and want to do critical listening, then its time to use the SOTA Cosmos Eclipse/SME V/Transfiguration Proteus combo. 

For a change of pace I will listen to the Well Tempered Reference and Ikeda 9 Kawami . Its a great sounding deck, but I meter its use because that will be the most difficult cartridge to retip. So I save it for those evenings of critical listening, and chose between it and the SOTA. 

My analog systems are decent systems, but nothing that is on the leading edge of analog playback. Simple gear for a simple guy. 



One thing I will say about direct drive turntables... In specific, the Technics SP series and 1200G/GR is they have to be the most neutral turntables I’ve ever heard, especially the newer models from technics. You will truly hear what is there on the source, good or bad. If you want a bit of coloration, which is not a bad idea for some systems, the Idlers and Belt drives will provide that. The older Technics SP tables have a slight warmth coloration but for some, thats perfect.
I bought a very early version of the Hyperspace, from one of their dealers in Florida with whom I never met.  When it arrived, I was chagrined to note the absence of that nice graphite-like mat.  I complained to the dealer, and his response was that I got an early model built before they went into production of that mat.  Instead there was a flimsy foam rubber mat on mine.  The problem was never put right, maybe because I am too lazy to make demands upon the dealer, or because the table sounded so good as it was.  That whole incident preceded my fascination with DD turntables and the Lenco.  I think I got tired of the Hyperspace because I hated having to give the platter a shove to get it started.
@lewm 

That's right. So did their other top tables. It actually looks like a composite of some description, but performs very much like the graphite slab on my DIY.
Nottingham Hyperspace has or had a very thick mat that appears to be graphite in photos, about one inch thick.
Neonknight, I feel your pain. Reasonable assessment. Which of your tables do you use the most? 
Antinn, great choice of mat. The triboelectric series you posted is upside down but it says the same thing. Materials at either far end of the series are problematic. Leather is right in the middle and has relatively neutral behavior. The problem however is that PVC is all the way at the top (in this series) And it is the material that is being rubbed into collecting electrons by the stylus not the mat. You have to discharge the record preferably while it is playing to minimize static build up and dust attraction. Interestingly paper is at the bottom and loves to donate electrons while vinyl likes to collect them. Paper is a bad choice for record sleeves But it is still the most common type of sleeve. Tells you how much the record industry cares about the longevity of their product.
Atmasphere, from an intellectual perspective I think you are right. However, the best tables have very inert platters and tonearms and you really only have to worry about their primary resonance frequencies. These are going to be so low that their impact on the sonic picture should be minimal if any at all. I have not seen any data but you would think  air bearings or opposing magnet bearings would have less rumble. Certainly less wear on the bearing but what about the compressor? I think the opposing magnet design as used by Clearaudio and SOTA is a far more elegant solution, nothing to break or wear out.   
As far as scar's question is concerned, everybody thinks what they own is the best or at least they want to convince themselves of this. There are several facts that can not be avoided. Direct drive turntables have a large spinning magnetic device right below a very sensitive magnetic device ,the cartridge. Aesthetically that is a huge problem for me even though I have never seen any non biased data to indicate that this is a problem. The Japanese make very trick products, well finished and jewel like. I think this sucks a lot of people in. There is a saying, the Chinese eat with their stomachs, the Japanese eat with their eyes. We listen with our eyes. If it looks good it must sound good. 
Idler wheel turntables have more moving parts in direct contact with the platter. They can be pretty quiet when new but will produce more rumble as these parts wear. No matter how quiet you can make an Idler wheel table you can always make a belt or direct drive quieter. IMHO belt drive is a simple low noise solution that is difficult for the other drives to out perform by any sonic measure. All the Mega priced tables are belt drive. The Air Force Zero, Basis, Clearaudio Statement are examples. When people do "cost no object" designs they always rely on belt drive. There are very few producers of idler wheel turntables today. The vast majority of them are refurbished old tables. Same is true of Direct Drive. Look at what the reviewers use as their reference tables. 
@chakster thanks for that suggestion. The weight shouldn't be a problem, as the standard rubber mat is probably not much lighter. I use an Orsonic DS-500 clamp (weighing 500 grams) with the Pioneer, but could always replace it with DS-250 at half that weight to compensate if need be.

@tomwh , Suspended the pieces with string or rope and tapped with a small piece of softwood. It was easier to match the frequency to piano keys than to set up a microphone, Revox, and frequency counter; and my spectrum analyzer is old and too heavy to move around, and not necessary for this. On the piano, the fundamentals were one and three octaves above middle C.

When the two were stacked on the spindle, the combination was dead, dead, dead. So when I play music, no colouration of any kind.
Terry9

How did you test for ringing?  A test record and your ears or some sort of test equipment?  Seeing those frequencies are at the heart of the midrange what did you hear when you played music.  I am truly curious.

Thanks
Tom
@chakster , graphitestore.com helped me with expert advice and a good product at a very fair price. I was told that they have provided platter mats before, but never as thick as an inch.

My big iron platter rings at 500Hz, the graphite top rings at 2000Kz, and the combination is dead as a tomb.
@terry9 

I have no source for graphite
As i can see The Mat is not pure graphite, it's different carbon graphite material, so the thickness is just 4mm and cheaper that previous versions made by Boston Audio. 

Another mat made from  extremely high grade of polycrystalline graphite
is OMA Graphite Mat  (6mm thickness), but i never tried this one myself, too expensive.    
@chakster , have you considered graphite? The good people at the Graphite Store were very helpful. I use 1", which they thought was a bit over the top.
Apparently Pioneer also adopted a very tight control. I refrained from trying out the CU-180 (which took some discipline), but did try alternatives within the same weight range, like hard rubber, cork and leather (even a sandwich of the two). This was no improvement. Quite the opposite in fact, so I decided to stick to the standard mat.

Did you try Boston Audio or The Mat ? This is a lightweight mat (454g) if your turntable drive suffering from heavy gunmetal mats like Micro @edgewear

When i’m looking at my Denon DP-80 or Victor TT-101 i think it would be better with lightweight mats like SAEC or The Mat. Because the platter is lightweight.

When i look at my Luxman (made by Micro Seiki for Luxman) i know that i can use Micro Seiki CU-180 on it and this is what i do. The platter is thick and heavy. But CU-500 mat is definitely too heavy.



WRT to platter mats, the concept that materials cannot absorb/attenuate vibration is not correct.
@antinn I suspect you misread my post, as you and I are on the same page w.r.t this statement; it is the same point I was making (or at least was attempting...)
Thanks for your thoughts, Ralph. About air bearings, I think that a very heavy platter on an amorphous carbon thrust bushing is virtually immovable - at least, mine is. You need a lot of force to raise it - and more to lower it - 87N per micron, plus the inertia. Compare that to a fragile cantilever. For radial stiffness, see above. The New Way figure is 34N/u.
@terry9 If the platter is unable to move up and down or in any other plane when subjected to vibration, such that whatever vibration might be present in the plinth is the same as that at the base of the arm and the surface of the platter, then the needed mechanical engineering principle is satisfied and the pickup will be immune to that vibration.

When I got my Pioneer PL-70L II DD turntable a few years ago I was planning to use a CU-180 copper mat, which had worked wonders on my Micro belt drive tables. I inquired at HiFiDo where I bought the table and they forwarded the question to Pioneer, who had serviced the table prior to the sale (Pioneer still operates a service shop for their Exclusive range and a select few other units, including this table).

The reply was firm: please refrain from after market mats exceeding the weight of the standard mat (made of thick soft rubber) as this will interfere with the PLL feedback circuitry and could compromise speed stability. Just as lewm suggested. Apparently Pioneer also adopted a very tight control. I refrained from trying out the CU-180 (which took some discipline), but did try alternatives within the same weight range, like hard rubber, cork and leather (even a sandwich of the two). This was no improvement. Quite the opposite in fact, so I decided to stick to the standard mat.

cleeds, I took examples of 1kg vs 5kg out of thin air. Most OEM platter mats weigh less than 1kg (2.2 lbs). I picked 5kg as the upper extreme, just because it is 5 times what might be the weight of a heavy OEM mat. Furthermore, a lot of the vintage DDs have rather lightweight platters.  So the total platter mass (platter plus mat) might be under 5kg.  When you add a 5kg mat to such a platter, you are about doubling its mass.  Can that be wise? Now we know you can bring any platter to a dead stop with palm pressure, so we know there is SOME platter weight that is too much. Just because a platter continues to rotate and the music is not obviously off-pitch on the low side,to indicate gross slowing of the speed, does not mean that one has done no harm to the operation of the table with a very heavy mat. Not too many people have the objectivity to be able to hear that (listener bias), and fewer people still will be able to make the relevant measurements that would reveal a problem. I certainly do not know that ALL turntables will be functionally harmed by a 5kg mat; I just used that as an example. Even among DD turntables, I think it’s impossible to generalize, because there is quite a bit of variability in motor torque and the "tightness" of the feedback loop (how much error is tolerated before a correction is initiated) also varies quite a bit from one design to another. For example, Technics seems to have favored very tight control. Whereas the Kenwood L07D uses a looser feedback loop. So perhaps I added to the confusion by seizing on two particular exact numbers in my first statement. I hope this is more clear. Heavier is not always better.
Nice Post Neil 😃
I have tried over a dozen different platter mats from copper, carbon composite, felt, suede, leather, glass, rubber etc and have found that the MICRO SEIKI Cu180 solid copper mat sounded subjectively 'best' on my VICTOR TT-81 and TT-101 turntables.
I was concerned however, at the increased weight on the relatively lightweight aluminium platters Victor employed.
More importantly....the method of Bi-Directional speed control Victor utilises might surely be compromised by tampering so drastically with the 'mass' of the platter...?
Strangely enough....of all the other mats and materials I tried, the VICTOR PIGSKIN 1mm original platter-mat sounded the closest to the Cu180 🤗
Those Victor Engineers knew their 'onions'.....😃
Jico came out with their own version a few years ago....but using deerskin.
Not as good....😕
My RAVEN AC-2 BD Turntable....because of its solid copper bonded top-plate.....sounds best without any mat.
Regards
Henry
@atmasphere 

Thanks for your thoughts, Ralph. About air bearings, I think that a very heavy platter on an amorphous carbon thrust bushing is virtually immovable - at least, mine is. You need a lot of force to raise it - and more to lower it - 87N per micron, plus the inertia. Compare that to a fragile cantilever. For radial stiffness, see above. The New Way figure is 34N/u.

What you get is a noiseless bearing, and you really can hear bearing noise. I've compared a first class turntable oil bearing with New Way air in a test rig, and it really is no contest. I've demonstrated sleeve bearing noise from a Premotec 1.8W motor through a belt - subtle, but it's there.

Could you please define 'isomeric isolation/mounting'? Is this a journal bearing in an elastic mount? Thanks!
I'm really glad to see so much information and ideas being exchanged here.
The point of my post is to get a general understanding of what each drive type might sound like or what people thought it sounds like, so it's good to hear opinions from many different people. I won't be picking just one turntable as I do enjoy having many options. At some point, I will be adding a DD turntable, it should be fun to experience all three drive types in my own system.
I do agree that there are so many different variables in a vinyl setup that contributes to the final sound from the stand it sits on all the way up to the record weight, so deciphering what is contributing to what is almost impossible.
lewm
Nearly everyone who replaces a 1kg platter mat on a DD with a 5kg platter mat, sometimes more than doubling the total mass of platter plus mat, says how wonderful it is. To me this says more about listener bias than it does about the physics.
Why? The physics of the situation are obviously different, so why would you discount that?
With any DD that uses any sort of servo feedback to maintain constant speed, the feedback circuit was designed for a particular platter mass.  If you change the platter mass dramatically, it is quite likely you will do bad things for speed constancy.  Likewise if you were to change to a much lighter platter compared to the OEM one.  Now, based on reports of others and my own experiences, there apparently IS some leeway within which some perturbation of platter mass will not do notable harm to speed constancy, but since every manufacturer had a different thought on the feedback loop and how to have it operate, there is no general rule about how far you can go.  I also don't know whether to credit some of the reports one can read on this forum, if you search the archives. Nearly everyone who replaces a 1kg platter mat on a DD with a 5kg platter mat, sometimes more than doubling the total mass of platter plus mat, says how wonderful it is. To me this says more about listener bias than it does about the physics.  And I also don't agree that there is a linear relationship or anything near to it, between platter mass and SQ. Belt drives with 200lb platters do not excite me.
"I did different thing and it’s not just about mass, because the SP-10 MKII does not have additional layer of the different material on top surface of platter as mk 3 model so i just used Micro Seiku CU-500 to upgrade it.

As the result, the platter made from one material was decoupled by gunmetal mat (material with different properties and different resonance). This is more like upgrading mk2 model looking at next mk3 model. There was the reason why Technics decided to add another later on top of the platter. So i had a gunmetal between the platter and vinyl record.

I asked why you just replaced original platter, because every Technics platter is balanced and there is a stamp about it. I have no idea who made the platter you’ve been using, maybe it was a bad platter (i mean not as good as the original) ? Increasing mass on Technics platter with gunmetal mat was huge improvement, but maybe not just because we add mass. This is what i want to say.

And another example is Kodo The Beat turntable, based on Technics motor, look at the Kodo platter.

Also nearly all turntables from Artisan fidelity comes with their own copper mats on top. Even tweaked Technics MK3 or Garrard 301

Even if the platter replaced with thicker and heavier one those guys always add copper mat on top of it, just like the latest Technics SP-10R.

P.S. @neonknight I am interacting here not with you personally, but with audio subject that can be interesting for others. No matter who is right or wrong, it’s important to add some information and everyone can decide what he like more. "

@chakster 

The above speaks to the concept that I had previously mentioned of the platter being critically damped and non-resonant being a more significant contributor to sound quality than platter mass as a sole indicator. 

I appreciate your above post, its far less combative and judgmental. I hope we can proceed forward on a more civil discourse. 
@atmasphere,

WRT to platter mats, the concept that materials cannot absorb/attenuate vibration is not correct.  Very thin viscoelastic materials can absorb surprising amounts of vibration - the energy is converted to heat.  This article is an excellent example - https://core.ac.uk/download/pdf/36723450.pdf.  Note that just about any thin material that can stretch such as a PVC film that protects a metal plate can act like a viscoelastic material.

Also, materials - metals while known to have different vibration damping characteristics, is actually well documented - download a report from this site: https://apps.dtic.mil/docs/citations/AD0640465.  Aluminum while being cheap has good damping characteristics and cast aluminum (i.e. ATP-5) can be better than extruded (i.e. 6061), but cladding improves it and magnesium beats all - but magnesium has that small issue of being able to burn quite vigorously.  But, some tonearms such as those from SME are manufactured from magnesium and for good reason.

I have personally had excellent results from a piece of very thin leather (sourced from a craft store) about 1-mm thickness with skin side down to a VPI aluminum platter and suede side to the record.  The suede side is very dense - much closer to a felt-type material so that the record mates to the record with little or no air gap, but does not produce lint.  A similar type mat (but pig-skin) was once available and very well reviewed -https://www.6moons.com/audioreviews/hiraga/mat.html.  

Also, as far as the triboelectric effect leather can vary based on type and moisture (which it can absorb) with the following being the latest (2015) triboelectric series (download from this site) - https://www.nature.com/articles/s41467-019-09461-x.

Just some thoughts,

Neil
I did different thing and it’s not just about mass, because the SP-10 MKII does not have additional layer of the different material on top surface of platter as mk 3 model so i just used Micro Seiku CU-500 to upgrade it.

As the result, the platter made from one material was decoupled by gunmetal mat (material with different properties and different resonance). This is more like upgrading mk2 model looking at next mk3 model. There was the reason why Technics decided to add another later on top of the platter. So i had a gunmetal between the platter and vinyl record.

I asked why you just replaced original platter, because every Technics platter is balanced and there is a stamp about it. I have no idea who made the platter you’ve been using, maybe it was a bad platter (i mean not as good as the original) ? Increasing mass on Technics platter with gunmetal mat was huge improvement, but maybe not just because we add mass. This is what i want to say.

And another example is Kodo The Beat turntable, based on Technics motor, look at the Kodo platter.

Also nearly all turntables from Artisan fidelity comes with their own copper mats on top. Even tweaked Technics MK3 or Garrard 301

Even if the platter replaced with thicker and heavier one those guys always add copper mat on top of it, just like the latest Technics SP-10R.

P.S. @neonknight I am interacting here not with you personally, but with audio subject that can be interesting for others. No matter who is right or wrong, it’s important to add some information and everyone can decide what he like more.







Why you did that ? You could just add Micro Seiki CU-500 gunmetal mat on top (perfectly matched). Here is mine. The weight of CU-500 is 2.7kg and it's 5mm thickness. That was huge upgrade for my stock SP-10 mkII.

When you're using not original parts, but some overkill superheavy custom platter why do you expect improvement ? Technics platter is already heavy.


Then why are you adding mass to the platter also? It is already designed to operate as the engineers at Technics intend it to, yet you feel you can improve upon that. 

This is no different than what I originally did, which followed the line of thought of increased platter mass would improve sound quality by less resonance and increased rotational stability. For me that was not the case, and I returned the item and gained a bit of knowledge/experience of what I prefer in turntable configurations. 

I am noticing something about you. It appears you are one of these people who believe that your choices are the only correct way to do things in this hobby. If others disagree with you or have a different perspective then they are misguided or ignorant. Audio is a journey and there are many pathways to take, and folks often have a different destination in mind and value a different perspective of what they get to hear and experience. Honestly, it would make my time here more enjoyable if you would refrain from interacting with me. Unfortunately this place does not have an ignore button. 

Another interesting tidbit on patter mass comes to mind. When I bought my SP 10 MK II I was quite content with it. I came across a custom machined platter for it that weighed about twice the mass as the stock one, made of stainless steel as I recall. I ordered it and installed it. What I found is that the sound became smoother but was robbed of life. The table was fully capable of keeping accurate speed at the stock platter weight, and there was nothing of consequence to be gained from increasing it, matter of fact it was a step backwards. Perhaps platter mass does matter, but only within the context of what the designer envisions.

Why you did that ? You could just add Micro Seiki CU-500 gunmetal mat on top (perfectly matched). Here is mine. The weight of CU-500 is 2.7kg and it's 5mm thickness. That was huge upgrade for my stock SP-10 mkII.

When you're using not original parts, but some overkill superheavy custom platter why do you expect improvement ?  Technics platter is already heavy. 


Turntables are holistic creatures, and placing a high level of importance in a specific design feature narrows our understanding of how things are ultimately sorted out in our analog playback systems.

Another interesting tidbit on patter mass comes to mind. When I bought my SP 10 MK II I was quite content with it. I came across a custom machined platter for it that weighed about twice the mass as the stock one, made of stainless steel as I recall. I ordered it and installed it. What I found is that the sound became smoother but was robbed of life. The table was fully capable of keeping accurate speed at the stock platter weight, and there was nothing of consequence to be gained from increasing it, matter of fact it was a step backwards. Perhaps platter mass does matter, but only within the context of what the designer envisions. The Well Tempered Reference indicates to me that platter mass has to reach a certain point for speed stability, and needs to be made of well damped and inert materials, but perhaps the critical level of mass needed is not as high as we would expect. But once again, its contained within the context of the designer envisions, and what that person works out to be the final balancing act.

I am a fellow of modest means, so I don’t play in the deep end of the pool. I have been fortunate to live with a variety of tables over the last ten years, which have included TD 124, 401, DP 75, SP 10 MK II, Rock MK III, and various VPI/Thoens/SOTA. But there are limits to my financial resources so I don’t comment on all at leading edge designs because that is not where I have any experience. My current tables are what my resources allow me to own. Currently have a SOTA Cosmos Eclipse with SME V and Transfiguration Proteus. Next table is the Brinkmann Bardo with Audiomods Series 6 and Ortofon A90. Final table is a Well Tempered Reference with Ikeda 9 Kawami. Nice tables at their price points, but they have their ceiling.

Resonance control is the name of the game. A table has two electro mechanical sources of energy, and two mechanical ones. Unwanted energy that makes it to the cartridge/record interface is noise and in a perfect world is shunted away. Motor vibration, bearing noise, uncontrolled resonance at the cartridge, and arm/bearing resonances in the tone arm, they all affect the signal being transferred from the vinyl to the phono stage. How the designer deals with it is what we hear, and I don’t know about you, but I certainly am not capable of passing judgement on each design characteristic that is made and assessing its contribution to the final product. At best I can have an opinion of what the overall sound is presented from the table, but nothing more of consequence. Bearing design, drive type, platter mass, arm design, plinth mass, isolation footers, suspension, power supply and so on, well I can have my opinions on what I think matters, but I really have no way of proving it to be true. So I would never make statements of fact in this is the way it is. Because I have no way of controlling all the variables in a comparison, and therefore can never really "prove" what I personally think is true. even just what I wrote above. Its just my observations and thoughts.
obviously a belt drive tt uses the platter mass differently than a direct drive or idler. which we could write a book about.

but if you investigate the top performers of each drive type they all have relatively heavy platters; and you would find that within each drive type that performance differences would generally relate to platter and plinth mass. it’s not that simple.....but it sorta is.

inertia plays a big role in musical solidity and ease. for tape decks too when you observe solidity of the transports and the deck structure.
In the past I would have dogmatically agreed that platter mass was a key point for good analog playback. I still think its a key contributor. 

However the Well Tempered Reference has shown me that is not a bit t Truth. I bet its platter does not weigh over 5 pounds, yet it has excellent sound quality, has solid speed stability, excellent bass response, and portrays space in a very believable manner. Is it the best table? No. But for its price point it was a very good table, and viable even in todays marketplace. It may not have a lot of techno wiz bang options, but it still gets to the heart of the music. Mass alone does not define SQ. 
Mike, Platter of SP10 Mk3 is listed as "10kg" or "21 lbs", everywhere. Not near to 30 lbs. It’s heavy enough as is

thanks Lew, my 9 year old memory was recalling how heavy the case was with the motor and platter and my guess was wrong.

but.......there is no ’heavy enough’. :-)

my CS Port has a 60 pound platter, the American Sound AS-2000 has a 200 pound platter.
Mike, Platter of SP10 Mk3 is listed as "10kg" or "21 lbs", everywhere. Not near to 30 lbs. It's heavy enough as is.
Platter weight 9.8kg = ~21 lbs.  I see no conflict with what you previously wrote, if you're talking about the Bardo.
@lewm 


Total 14.8 kg (Chassis 5 kg, Platter 9.8 kg); Power Supply 0.5 kg


So 21.6 pounds.

I even checked my math with a conversion program!

@scar972  There's a photo on my System page. It's an aluminum light grease bearing with POM linings and ceramic ball. Made by a guy in Asia. SPH. sphBearing AT gmail com
I did respond to this, in my post just prior to this.
Apologies, somehow I managed to miss it. Now remedied.

I took your original post to mean a mat with the same universal durometer as vinyl, which was why I wondered. Thanks for clearing it up for me.
New Way air bearings have amorphous carbon faces, resulting in literally millions of ’apertures’. I saw a U-Tube presentation of a shaft rotating in an air bearing (maybe New Way), spinning freely, when the high pressure air supply to the spindle was cut. The shaft came to an abrupt stop with a bang - it was immovable. Now that’s low tolerance!