Tables That Feature Bearing Friction

I went through Mark Kelly's extensive teachings. Good research and explanations, but he is not focussing upon the center point.

Some people will hate me for this, but I want to postulate a short and clear statement ( and I ask everybody to give it some deep thought before telling me I am wrong....) regarding ANY principle in turntable drive (idler, dd or belt):

The motor of a turntable has ONLY 2 jobs to handle.
1.) bringing the platter on speed
2.) preventing the platter to slow down once it has reached that constant speed

There is nothing else the motor / drive has to do.
Physics and logic will result in a huge inertia ( = huge mass of platter) providing an extremely constant speed by its own rotation. It will too result in a coupling which does allow some slip at BOTH ends of the drive system - platter AND motor (such that little variations in speed generated by the motor itself will NOT make it onto the coupling device (string, belt - whatever). A say 35 -50 lbs platter on 33 1/3 rpm rotation has a VERY constant speed (much better in its constant speed stability than almost all motors in use in todays high-end turntables).

It is not about control between motor and platter.
The platter will not get any "faster" once it has reached its determined speed.
It gets slower due to air resistance, stylus drag etc. But those are constants in real world application.
So - all the motor and its coupling device have to do is preventing the platter from getting slower.

This automatically does lead us to a definite slip coupling and a huge inertia.
The way to get ultra constant speed and practically zero derivation in as much inertia as possible (in real world application).

Give it a deep though before jumping to the keyboard telling me a stupid, narrow-minded fundamentalist.

Its all about masses in motion.
Again - its all physics.

The trade-off is a long time to arrive at stabilized (2-4 minutes) speed.

As for the Micro Seiki original belt / strings. The Micro Seiki RX-5000 came first with a fairly strong and wide rubber belt of very high quality first. However they did recommend too - right from the start - using an aramide string ( made out of 134 individual fibres ) to get the very best results possible.
Because of less vibration transmission towards platter - and: slip coupling....... resulting in much better constant speed.......

In fact Micro Seiki 's engineers were the very first to realisze the potential (in turntable design...) of high inertia coupled with thread drive resulting in superior extremely constant speed. Low grip, slip coupling and let the huge mass in rotation do stabilize itself.
I mean - it works pretty well with our planet (and a few trillion other planets too.... yes, I know - there is no stylus drag on terra..... and it is a rotation in open space = vacuum) - why shouldn't it work with our turntables??
But again - you can not do it cheap.......... huge mass platter ( = expensive), very strong yet high quality bearing to handle huge mass platter (= expensive.....), high quality motor (good capstan - for instance...) (= fairly expensive again).

Not to speak about suspending the combined high mass with super low frequency from building resonance......

Dertonarm, I completely agree with you that the job of a turntable motor is only to bring the platter up to speed and then keep it from slowing down. Where I disagree is that platter mass alone is the the cure all for speed stability. A large platter mass does not negate the importance of motor quality or the quality of the drive mechanism.

In this thread there is a lot of discussion about physics. Of course what is happening in a turntable is about physics. But I posit that good turntable design cannot be purely about physics. There are several reasons that this is the case:

1) Nobody fully understands exactly what the physics are. There are a lot of very subtle things going on in a turntable that to date are not fully explained. There are plenty of theories and opinions, but not a lot of facts.

2) Good turntable design is all about producing good sound. Unless the relationship between sound and physics is fully understood then physics alone cannot be an effective method for designing a good sounding turntable. Harmonic distortion in an amplifier is physics. But building an amp with super low distortion often does not produce good sound.

3) Design is also about compromises. There are compromises to control costs that apply to any turntable design commercial or otherwise. A good designer will make the compromises that deliver the best value for the money and effort expended. In addition to cost compromises there are compromises related to balancing of conflicting technical goals. Coupling vs isolation, damping vs rigidity, light vs massive. Focusing on only one objective usually delivers poor results.

4) Like it or not good sound reproduction is a subjective pursuit. There is no such thing as an ultimate sound system nor is there or will there be an ultimate turntable. Everybody has their own set of musical priorities and no design will be a fit for everyone.

Back to platter mass I have done a lot of experimenting with various platters. I find that to my ears heavier platters do sound notably better. I also have found that a heavier platter makes that quality of the motor and drive system less critical. But even with a 70 pound platter subtle changes like belt material and even the motor pulley composition are still easily heard and are musically significant. Less subtle changes like rim or direct drive are even more obvious.

Dear Dertonarm: I agree with you on your TT approach. IMHO this is a " road " to follow but IMHO it is not the " only and best " road. There are other examples speially on DD TT designs and certainly there are other " roads " in the brain of TT designers that they are not try it yet.

I agree too with Teres that physics tell us part of the whole " history " but there are several factors that affect and change what we are hearing it does not matters if the physics is on target, of course that everything the same a TT or any audio item that achieve a scientific approach is a better one and has to perform in better way too.
IMHO I think that are many " things " that till today no one already made a in deep research to find in a scientific way the. why's, where's and how's on each single TT design.
I know this because is something that I'm learning through our self tonearm design, where I'm " discovering " things that I never imagine can/could affect to quality performance.
Well, IMHO that happen too with TT's where scientific rules/law can't give us all the answers ( relationship factors ). Of course that if someone makes the research can/could have scientific answers but maybe to find out all those answers he will need not only know-how but a lot of time,money and common sense.

I like you and almost all people that cares about top quality performane/designs hate compromises/trade-offs but unfortunately these ones exist and the best each one of us can do is try to choose the " best " overall ones: such is life!

Regards and enjoy the music.
Raul.