Pros and Cons of Platter Mass

I am curious about the pros and cons of high and low mass platters in terms of physics and sonics. Like, why a designer would choose one over the other, and why any of you would have a preference. Although I do not anticipate any freak arguments about which is best in this relatively benign topic, let's try to keep this normal, ok? Thanks
Higher mass minimizes wow and flutter because the greater mass provides more inertia. High frequency mechanical noise causes less audible flutter because the platter is so massive that it takes a lot of energy to accelerate and decelerate it rapidly in an audible fashion. Low frequency mechanical noise is also less audible for the same reason. Many years ago I had a budget table with a truly lightweight platter that would slow slightly when the needle hit a loud passage on the record where the bigger groove modulations would cause frictional slowing. This was audible as wow. My current heavy platter doesn't have this susceptibility. The single greatest drawback of heavy platters is, in my opinion, that they require bigger motors or longer spin up times to reach playback speeds. (Of course, they also cost more.) In extreme cases, you have to give them a head start with a shove from your finger.
Jameswei is correct, his answer is absolutely in accord with my own experience, and I have owned perhaps fifteen turntables .

My current table utilizes a 70 pound platter and must be push started, even though it is air bearing. No doubt it is the quietest, most speed accurate and lowest wow and flutter of any table I have ever heard. Not too surprising, considering the laws of physics.
Can't tell ya...however, I do know the pros and cons of hitchiking!
Fatparrot, does it include a guide to the galaxy?
I hope this doesn't qualify as a freak argument, but I believe the ideal turntable platter would be close to no platter at all (the low mass concept taken to an extreme). The platter serves only two purposes, first it provides a place for the disc to sit and second to impart the motion of the motor to the disc. Neither of these functions requires high mass. The functions that Jameswei attributes to the platter should actually be performed by the motor. To the best of my knowledge only two turntables have been designed along these principles - one by Ed Meitner and another out of England by Real Sound. I've heard neither of these turntables so I no idea about the quality of the implementation. I suspect the reason that there are so few turntables designed with minimal platters is the lack of suitable motors. Motors designed from the ground up to properly perform what a turntable motor is supposed to do and not rely upon the platter to correct for its failings.
Notwithstanding the above, I have an RPM turntable with a relatively high mass platter.
Onhwy61. In an ideal world, your ideal zero mass platter would be great. In the real world mass is required to smooth out the energy drain from the stylus retrieving heavily modulated passages from the vinyl.

The motor you propose would have to not only turn at exactly the correct speed, it would have to recover in microseconds to any variation in drag coefficient or velocity changes. This might be possible, but for the present time, a heavy platter turned by a belt to isolate the less than perfect motor is the best we have. Much like the designers decided on for your RPM.
Albertporter makes solid sense and as a practical matter a high mass platter is the way to go. On the impractical side, it's interesting to note that Andy Payor's Rockport turntable uses a direct drive motor that is capable of speed accuracy in the microsecond range. The motor utilizes extensive microprocessor controlled speed correction and is reputed to cost $15,000. Payor mates it with a high mass platter.
I agree with the above comments, but would add that as with most things, there are no absolutes. The correct amount of mass within the context of the other design characteristics of the turntable, and ultimately the entire analog playback system is most important. In my experience, and based on my tastes and priorities, the turntables that let me get closer to the music, as they say, have been of the high mass platter type. But that is because to me, the weightier, denser, and more harmonically natural sound that heavier mass tables, as a class, seem to have is more important than the little extra bit of liveliness that the lighter mass platter turntables seem to have, as a class; sometimes at the apparent sacrifice of a little tonal richness. There really is something to the "the Linn gets your toe tapping" stuff. To my ears, there are times when recorded music needs to move very very quickly to really get close to achieving the "aliveness" of the real thing; and some tables, particularly the Linn types, allow that better than others. Some say that it is the resonances or ringing(distortion) that a table like the Linn has that gives that illusion, maybe, but I do know that many big mass tables that I have heard can sound a little like the music is a bit too under control; not expressive enough. I often miss the excitement that I hear in a table like the Linn. In fact, a Linn is probably my next major audio purchase. The idea of owning and keeping two turtables in the year 2002 makes me chuckle. I have experience with AR, Technics, Ariston, Rega, Linn, Well Tempered, Forsell, and VPI (which I own), and have heard Goldmund, Basis, Kuzma, Roksan, Meitner and others; I suspect that there are tables that I have not heard that strike a balance between these two major considerations.

By the way, I heard the Meitner at the first Stereophile show in NY, and unfortunately was not impressed. I still remember that it was one of my least favorite demos. With Acoustats and Meitner electronics there was very obvious wow; I remember being very surprised that the hosts would find that acceptable. The absence of a platter for the record to push against and thus flatten itself out, at least in part, made the playback of anything but perfectly flat records unacceptable IMO; the pitch fluctuations in the music were ridiculous. Imagine negating the benefits of clamping; it just did not work IMO.

Still nothing like vinyl.

Looks like my physics class paid off. I thought there might be more implications of platter mass than I initially theorized with before starting this thread, although Frogman's (great moniker) comment on aliveness and resonance was new to me. And due to the number of low mass turntables, I also thought the responses would have been a little less one-sided. I am immaturely happy with the responses as my TT is a high mass design (and less expensive than many low mass ones). Thank you everyone.
with heavy platter (or added weight stabilzer) does it really stress the motor or just negligible..
i have slj2 and normally add weight, i think it improve sound, but maybe stressfull to motor.  thanks.
From my investigations undertaken of how a increased Platter Weight can impact on a TT that is not supplied with a Heavy Platter.                      I have learnt that the Thrust Pad can show signs of increased wear after a lesser period than anticipated, where inspection of the part has shown noticeable indentation occurring from the Point Loading.
There are harder Thrust Pad Materials that will alleviate this condition and offer improved performance and longevity of use.
There is also the condition that can be impacted on where a Spindle can have a eccentric rotation and the addition of Platter weight can cause an increase to the force from the Spindle when coming into contact with the Bearing Bush.
A Hydrodynamic condition for the lubrication may prevent the Spindle/Bush coming into contact. From my investigations of certain vintage TT's there is not much evidence to show the Bearing / Bush interface had successfully maintained a Hydrodynamic Interface, there was possibly not a design from the outset to produce the interface.

The reports of increasing the Mass/weight of the Platter are usually seen with a positive appraisal where there are perceptions that a improvement is present in relation to noise reduction.

I have not seen measurements that will show changes that are able to to support such modifications, the usual, is that there is a trend and the individuals carrying out the mod's are collective in their positive appraisal.   

In my opinion, the platter, spindle, and bearing with or without thrust pad form a closed system in the sense that they are carefully engineered to work well together in a well designed turntable. Therefore I would be loathe to do anything to dramatically alter platter mass or the materials used at the bearing/thrust pad interface, or even the lubricant, without considering the effects on the other constituents of the closed system.
I would be loathe to do anything to dramatically alter platter mass or the materials used at the bearing/thrust pad interface, or even the lubricant, without conside   ring the effects on the other constituents of the closed system.

I wish more folk would heed this sage advice.

I have seen a number of Garrard 301/401 TT's with aftermarket thrustpads/balls that have damaged/worn the spindle.
I have seen many TT's with accelerated bearing wear from using "better" oil.

I have learnt that the Thrust Pad can show signs of increased wear after a lesser period than anticipated, where inspection of the part has shown noticeable indentation occurring from the Point Loading.
There are harder Thrust Pad Materials that will alleviate this condition and offer improved performance and longevity of use.
And you forgot to add may well stuff your main spindle.

By using a "harder" thrust pad you increase the chances of wearing out your spindle - yippee - try finding another spindle for that vintage turntable that is no longer manufactured. The improved performance will only last a year or so until the spindle is stuffed.
Peripheral Rings and Puck Weights are a common used method, and when used are adding mass, where the Peripheral Ring has the added effect to increase inertia.
Each of these ancillaries when in use, add weight to the Platter and increase on the load being applied to the Spindle and Interfaces.  
I am not aware of any TT Producers putting forward disclaimers that advise against the use of such ancillaries. These ancillaries are commonly accepted as methods to be used to Clamp a LP to a Platter.

To date I have not seen any reports that suggest a detrimental outcome to a Bearing Assembly has occurred as a result of these ancillaries being used.  There may be others that know a different outcome.
Never understood the idea of using a hard thrust pad. Any mechanical engineer is taught that one surface of a plain bearing should be hard and the other sacrificial surface should be soft. Hardened steel shaft running in soft bronze bearings or a very common usage is in engine bearings, a bearing shell with layers of material that can be scratched with a finger nail that runs against a steel or cast iron crank pin. As long as there is a film of oil between the surfaces than no wear will occur.
Wear should always take place in the softer sacrificial material.
A time proven design for a turntable thrust bearing is a steel ball at the bottom of the spindle and a Delrin thrust pad. I have used it in my rebuilds and the Delrin seems to hold up very well with no wear on the steel ball.
My lubrication of choice is a light hydraulic oil, usually AW-32. I don't use engine oil, it has tons of additives, most not useful in a TT spindle at all. Any of the oils that have particles added and being touted as some kind of "super lube" have no place in a TT as well.
I don't understand the folks that think they will gain something by using some kind of magic oil, this stuff has been understood for well over a century and is proven. Most commercial TT oils are either a light hydraulic oil or very similar. Most general lubricants that you purchase in a hardware store are again just hydraulic oil.
Turntable manufactures don't have a tribologist on staff to formulate oil, they will look at the engineering specs on the oils available and choose one, mostly it's just hydraulic oil. This isn't rocket science.
The point made about Sacrificial Surfaces are important and within the Bearing Housing there are designs in place to address this.
The Spindle is usually designed to be the part that has the Hardest Surface and in a good design will usually be produced with a Case Hardened Surface.  
Bush Materials are selected that are produced to have lessened surface hardness than the Spindle.
A vintage TT that has not had a life of function with a Spindle / Bush Interface where a Hydrodynamic condition is present is at risk of having produced a wear to the Bush Material. When the Bush is produced from a Metal, the risk also becomes that abrasives may be in the Bearing Housing and having an unwanted impact on the important parts and interface surfaces. The Wear can impact on other important areas of function, especially increasing the likelihood that an eccentric rotation will develop.

A Spindle does not usually interface directly with a Thrust Pad, there is a intermediary part used that is Sacrificial, in many cases this part is a Metal Ball, that can be found to be a interference fit into the base of the Spindle or in other cases a fully exposed ball that is a standalone part.
These Balls have been witnessed scored on the surface as a result of being in an environment that is abrasive. 

The modern designs for the sacrificial parts used at the interfaces are more commonly moving away from the use of Metal and are leaning towards the use of Thermoplastics as a Bush and Thrust Pad, and the Metal Ball is more commonly seen removed from a design and exchanged for a different material that has formed the ball.

In relation to vintage TT's with long periods of use behind them where a bearing housing is using Metal Sacrificial Parts, it is difficult to condone that a application of a new lubrication only is the required treatment to produce a environment for the Spindle to function without impediment.

There are many grades of Thermoplastics with different properties for the resilience to wear.
POM and PEEK are two examples and the PEEK is common choice to be used when a Platter is going to be above a certain weight.
It does not have a property that would wear a correctly selected interface ball or will it cause damage to the Spindle.
There are more modern Thermoplastics that can be selected with properties that are further suited to the use within a bearing housing.     
@lewm , you need to add motor torque to that list.

I think as everything in life there has  be a balance and it depends on what type of drive is being used along with it's performance. The best direct drive motors do not require as much mass as the best belt drives.
Mass does not protect you from rumble. It might lower the frequency a little but you are also adding more thrust to the bearing, increasing noise and wear. 

How much mass is required? Whatever it takes to get the best performance and no more.
What confuses me the most is how a topic sat dormant and was revived 19 years later. I had to check to see if the OP was still with us and certainly glad he is. 
My TTW table’s plater separates into two parts for convenience, but the total weight is 70lbs. The copper weight and periphery ring add more and I’d love to know how much the the flywheel effect adds since the TTW periphery ring has brass weights.
I can say going from a less massive table to the TTW added dynamics and bandwidth to the sound. Also I feel the mass allows vibration from the stylus in the groove to sync, and the center weight and periphery ring holding the LP down essentially make the LP weigh 70lbs lowers distortion tremendously.
It is becoming more common for manufacturers to use a magnetic thrust mechanism. No ball and no thrust pad. Spindle wear is much less of a problem because of the greater surface area involved. Here, lubrication is quite effective if the bearing is designed properly. My subwoofers tell me there is most definitely less rumble with magnetic thrust bearings, at least the one I am using. 

Magnetic thrust bearings also allow more platter mass without increased wear. The same is true of real air bearing turntables. Frank Kuzma redesigned his big table with an air bearing and increased the mass of an already huge platter by about 1/3rd. I wonder if all that air rushing around increases noise. What if it blows on the tonearm?
The best direct drive motors do not require as much mass as the best belt drives.
If you look at the Technics SP10 series - the most powerful SP10mk3 has a mucher higher platter mass (25lb ) relative to the weeker motored mk2.
Similarly with the Kenwood L07D - highish platter mass was oart of the design - the argument was high inertia, resistance to stylus drag.

Finally the most powerful direct drive motor built by Technics for lathes - the SP02 - dwarfs the motor in the SP10mk3 - but it was specified to be used in the Neumann lathe with an added 70lb flywheel.

If you build a platter out of weetbix, it will still sound like weetbix irrespective of drive topology.
It is becoming more common for manufacturers to use a magnetic thrust mechanism. No ball and no thrust pad.

And it is a stupid idea - you cannot accurately measure the groove when the platter is not grounded or referenced to a fixed point relative to the tonearm.

Same as air bearings, platter is not grounded, and it is not possible to accurately measure the groove.

Depends on the design my platter which is all copper weighs 80 pounds on TW AC3 turntable sounds great.
My ears tell me to respectfully disagree with dover about magnetically suspended platters.  My Clearaudio Performance DC Wood tt has a magnetic suspension for the platter, and I feel that it imparts a remarkably quite effortless sounding accurate reading of the information in the grooves.
Looking at things from a different angle what "quality" tables
used a rather light weight platter and did they have a particular 

One example would be the Victor TT-101  of which a few here 

Playing the devils advocate if a heavy platter is not rotating 
at the correct speed is it then more difficult to manage/correct?

Playing the devils advocate if a heavy platter is not rotating
at the correct speed is it then more difficult to manage/correct?

Correct. Which is why the simplistic answers are... simplistic.

Merely turning the turntable on- just spinning the platter, not even playing a record- sets the entire system in motion and vibrating. No bearing is absolutely perfectly smooth. Nor any motor, nor belt. All this stuff is vibrating like crazy making noise the cartridge is going to pick up, and we haven't even started playing a record yet.

People need to understand mass is not magic. If all you are doing is adding mass to an otherwise identical platter then yes, that is better. At least in the case of the ones I have heard compared side by side. 

But who says we can only change the one thing? That's why these questions that like to look at just one aspect are so tedious. The only good thing about them is every once in a while they serve to maybe help make people aware the world is nowhere near as simple as these kinds of questions make you think.

Besides vibration there is speed stability. Don't care how massive the platter, dragging a stylus through music creates constantly varying braking loads. And yes it does matter. Some motor controllers allow user changes to response curves. One setting the controller responds quickly with a lot of torque, another slower with less, and all kinds of things in between. It is easy to hear the difference even with a very massive platter. 

Mass is not magic.

This sort of drag, you don't hear it as pitch but rather a loss of immediacy or dynamics. 

My last 2 tables, one was high mass, 25lb lead shot filled platter 3" thick. The other platter maybe about 3lbs couple three different materials an inch or so thick and smaller diameter as well. To hear the high mass guys talk this should be no contest, and it isn't. The smaller lighter platter kicks butt, far more dynamic, much better timbre and timing, just across the board superior.

Even something as seemingly simple as a platter there is a lot going on.
You are looking at this upside down -
the objective of a high mass platter is to make it immune to stylus drag.
How heavy does it need to be - Brinkmann says 15kg minimum, Kuzma  claims similar.
Kuzma says stylus drag cannot be eliminated completely - so it boils down to heavy platter, high resistance to stylus drag vs light platter less resistance to stylus drag which would require fast and smooth non invasive speed correction.
So it comes down to which is the lesser of the two evils - very small stylus drag effects on a high intertia platter, or larger speed errors corrected more vigorously on a light platter.
Unfprtunately cost always factors into design high mass platters with sutiable quality bearings are not cheap.

here is an example of high mass platter speed stability -

+1 dover

IME, speed consistency of "heavy" platters is a non-issue, given the drive systems that are now available.