Skeletal vs Plinth style turntables

Here is the issue in mechanical engineering terms. It is not a lot different from the steering and suspension of a car.

In a nut shell:

the plane of the platter must be consistent with the plane of the cartridge. As the arm moves the cartridge must remain in this plane. Since the platter must revolve, there can be no slop in the bearing such that the platter can deviate from said plane.

As the arm must be set at a fixed point, it can then be seen that if there is any difference that occurs between the point of the arm and the surface of the platter that is will manifest as a coloration of some sort.

For this reason, the coupling between the surface of the platter and the locus of the cartridge cannot have any slop of any sort. To this end, the coupling between the bearing and the base of the arm must be as precise and tight as possible; IOW of a singe piece which will not respond to vibration, as if any differences can occur they will be interpreted by the pickup as coloration.

What this means is the more dead and the more rigid the plinth is, which also holds both the arm and the platter, the better the 'table will sound.

Parrotbee
I look forward to you posting pics of your creation. Good luck with the project. Also can you advise more details on the microscope isolators?

Atmasphere
Dimensional stability.... You said it far better than I

Thanks

Hi

I must say that I am not a big fan of arm pod mounts for turntables because then you are reliant on the platform to couple the platter cartridge arm loop - I am sure some will outcry at what I have said, but I think arm pods are quite a clumsy solution to a problem.
I had a look at few different large microscopes, and they have motion control dampers - I am looking into the best VFM/performance ratio.
I am gonna post, at some stage, a full set of pics from my drawing board plans to the build.

Viridian
Given that any structure has a resonant signature, the question then becomes not, "which is the most dead" but "at what frequencies are the resonances in the structure and what is the amplitude, magnatude, and Q of those resonances?"

+1 Excellent Viridian

One example of this.

"Granito is a material composed by little pieces of marble of very different origin agglomerated inside a mold with cement. Machined and polished. The resonance of the plinth with its suspension is about 5Hz and it is well absorbed by the air cavities"

Mr. J.C. Verdier (R.I.P) in describing the Verdier Vintage La Platine Granito.

Along with La Vintage Platine, I also "still" own two full plinth TT's, My 100 lb Jean Nantais Lenco, and an SP10MKII that can actually be put in one of two configurations. 1) A Full Plinth - 70 lb Multi 6 Layer Birch/ One layer MDF or 2) a Rigid (in your words ParrotBee) Skeletal Plinth.(both plinths which are DIY sourced and put together). The SP10mkII is sort of a pet project going way back now. fwiw I prefer it in its Rigid Skeletal Plinth form. It is more neutral sounding.