A Copernican View of the Turntable System

T_bone, Why not use an actual M-S armboard (if you are using an M-S tonearm)? I think reproductions are made.

Halcro, You are obviously an architect. (I already knew that.) But doesn't all cement shrink to at least some degree whilst it is setting up, no matter how low the water content? And wouldn't even a small amount of shrinkage cause the inner cement cylinder to pull away from the walls of the metallic tube? Thus, could the cement cylinder become loose and actually fall out of the tube?

By the way, this issue of "shrinkage" was covered in a Seinfeld episode.

Lewm your comment on the cantilevered arm board pod was visualized completely.

It's just another design method that would be an easy build, fairly inexpensive and very convenient with use.

More importantly emphases are on further isolating tone arms from imposing colouration's including help reducing vibrations of all sorts by way of experimenting with arm board material type.

Dear In_shore, What you say is also well and good. I further still maintain that the tt and armpod ought ideally to be in unison, so use similar strategy to isolate both tt and tonearm, a la the Da Vinci. I would not favor using a Da Vinci or similar armpod with a tt that was sitting on AT616 feet, even though I know that others here are doing something akin to that and getting what they interpret to be great results. I think that might mean that the level of our concern regarding structure borne and internally generated forces amounts to massive overkill.

I dont agree with pods but I have thought about mounting a cantilivered armboard off the plinth using 3 mini spikes machined from grub screws so they are adjustable ( for levelling the armboard relative to the turntable bearing ) and using a nylon nut and bolt through the centre of the triangle formed by the grub screws to anchor the board. This arrangement would give you true 3 point mounting, energy dissipation and levelling capability.

Dover: For whatever reason, cantilevered armboards appear to increase the bass volume and power, compared to non-cantilevered armboards. This is from my own experience, as well as from discussing these issues with other turntable designers.

Still, if I were to design an ultimate turntable, it would have a low-noise platter bearing, an ultra-rigid connection between platter bearing and tonearm pivot (ideally machined as one piece), a helluva lot of moment-inertia in the platter, and even greater moment-inertia in the plinth (which would be designed for low structural and cavity resonances).

The complete turntable would be integrated with a self-levelling air isolation platform, which would rest on a stone column that goes directly into the ground, without any contact with the floor of the listening room. Surrounding the turntable (but not contacting it) would be a double-wall acoustic shield, vacuum-evacuated between the walls to minimize energy transmission.

cheers, jonathan carr (using 60kg solid zinc plinth to connect platter to tonearm)