2020 update : JC Verdier La Platine

Ct, Your remark, to follow, makes no sense. "If Chakster provides the answer to us, he will have also explained to Lewm why his post based on theory, does not work. "
If you want to say that despite its flaws you dearly love your Verdier, that's great.  Every turntable has flaws in its design, sometimes great, sometimes small.  I have heard the Verdier many times, and I cannot say I hear any major problem that I could attribute to the turntable.  But "belt creep" is a fact of life. When I prefaced my remark by "in theory", I meant that according to the facts of belt creep, I would expect the Verdier to exhibit some measurable manifestation of it, based on the custom of placing the motor very far away from the platter.  Because I have never made any measurements of the speed constancy of a Verdier, my thoughts on it in relation to belt creep are "theoretical". I think we went around on this issue once before; you, or whoever was the protagonist, were indignant that I assumed the motor to platter distance is great.  (I assume it because every home or show demonstration of the Verdier I have ever attended over a period of 30 years was set up that way.) What would mitigate belt creep is that most strings used for turntable drive are relatively noncompliant. That does help.  To further minimize belt creep, you would want the motor closer to the platter.  As to the top heaviness of the design, that is just another fact, along with the spongy feet. Do you agree it would be better to use noncompliant feet?  And why do you think I don't love music just as much as you do?

chakster
What is going to happen if you replace your AT 616 footers (which btw I also happen to own) ..... and place four blocks of slate material in their place?  

I've noticed you've got those AT-616 pneumatic feet under your "naked" SP10 mkII that you're using with tonearm pod. I must say i never tried any pods or "naked fashion" style with my SP-10mkII. Also i don't have SP-10 mkII anymore, i've been using mine in a custom made teak wood plinth or very small rubber feet.  Now my turntable is Luxman PD-444 and i made my metal custom racks for them. 

Anyway, i can't explain anything to Lewis as he's much more experienced that me when it comes to different turntables. 

However, i love all my direct drive turntables, some of them are expensive, some are not so expensive, but i can't detect any lack of speed accuracy or any other problem with Lux PD-444, Denon DP-80, Victor TT-101, Technics SP-20 and SP-10 mkII.  

chakster I've noticed you've got those AT-616 pneumatic feet under your "naked" SP10 mkII that you're using with tonearm pod.

 

@chakster 

Look again.  the AT616 are no where near the SP10.

The Sp10 is held up by Solid SS columns. These columns are bolted into the Sp10 and the Plinth. 

The AT616 are then placed under this plinth - Three of them.

The Plinth holds the Armpod as well.

Understand that this setup went with through many versions.

Prior to the that Sp10 project I had personally built a plinth of multi layer birch / mdf and aluminum. I believe its around 50 lbs.

Here is a picture of it.

https://photos.app.goo.gl/XYRehswH3vhtABBP6

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What I was getting at with the AT616.

The AT616 are what I would call a first level good pneumatic suspension.

They are not as effective as the feet under La Platine.

I used the slate material as an example to you, because you were referencing a dealer on that other thread that sells alot of turntables made in slate which I imagine he gets from a local quarry. If you replace the AT616 with the slate you create a path both ways for vibrations.  

The turntable would no longer be self-isolating.

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@lewm @chakster 

lbelchev discussed La Platine concept/design on the other thread that both of you have posted to.  I believe the following post is eloquent and self explanatory. 

https://forum.audiogon.com/discussions/verdier-platine-or-nottingham-analogue-hyperspace/post?postid...

@ct0517  yes i saw your pictures and understood construction of your SP-10 plinth system, it is still "naked" or not traditional plinth. Not sure why your SP10 II is not stable, because it is a stable Direct Drive motor and seems like everybody happy with it. 

Personally i have never used a slate plinth, i even started a thread on here about different plinth for SP-10 (from Steve Dobbins, OMA etc), but i gave up and bought another DD that does not require all that mess up with a plinth. The feet on PD-444 are suspended, but the plinth is super heavy metal, no more question about the plinth for me, i am happy. My AT-616 are for Denon DP-80 plinth and for Victor TT-101 plinth. 

lbelchev explained La Platine original concept, sounds good. 
OMA changed the concept using slate plinth for this turntable. 

What i don't understand is your criticism of Direct Drive speed stability. 
Lewis perfectly explained the weakness of the belt drive. 

@lewm
Besides other problems with that, that construction would also tend to be a cause of speed irregularity, as stylus drag waxes and wanes over the course of an LP.

Lewm, here is a nice explanation from the manufacturer Jean Verdier:

"Now, let us approach another point: Dr. G.W. explains that playing a record with a stylus consumes energy and that this energy is variable on account of the changes of musical modulation, resulting in drive speed variations of the platter.

That is absolutely correct and it is one of the basic problems facing the turntable designer. The author than explains how to remedy this: the motor must renew the energy as swiftly as possible to keep constant speed, that is the reason for using a low inertia motor. I think that if this were true, no turntable could work well, because no motor is good enough. Fortunately, we can make use of more powerful tools to settle that problem.

The first tool is well known, it is the platter’s inertia. The heavier platter, the more it works to counter momentary variations in speed, but the challenge is to make a very thick and massive platter which doesn’t ring like a bell.

The second tool is less well-recognized than the first: the constant-coupled brake system. Since the player stylus consumes variable amounts of energy, we have to mask that consumption by permanently consuming much more energy by the use of a brake. The larger the ratio between the energy consumed by the brake and the energy consumed by the stylus, the better turntable work.

To be clear: only a few models of turntables have this device. To understand the concept better, have a look at a Thorens TD 124 which uses a brake with Foucault’s current excited by a permanent magnet, or EMT 927 which has a completely mechanical brake consisting in washers placed around the axle with the capability of adjusting the pressure and therefore the braking action.

On my turntable, the brake is present, but invisible to the casual eye-it is furnished by the axle and bearing. The two parts are unusual in their very large dimensions. The two facing surfaces of about 60 cm2 separated by lubricating viscous oil form the brake."

We can see this brilliant principle in 2020 - CS Port Analog Disk Player LFT1 (£48,000.00): "In LFT 1, the rotation control is not performed, and the constant speed rotation is left to the high moment of inertia of the 27 kg platter, creating a rotation free from unnecessary vibration caused by the control. Only the positive direction force is applied from the motor, but by using a coreless motor with LESS MOMENT OF INERTIA, the influence of the vibration is reduced."

There are more hidden things, but modern audiophiles are looking for exactly 33.33333 ....


Cheers