Vintage DD turntables. Are we living dangerously?

Lewm,
Okay, take away the movement in unison aspect of a suspension, and exactly what are these extraneous sources of energy?
Why is it better if they are joined by a plinth or whatever, than planted on the base?
Don't tell me they will act in unison to some undefined energy and cancel affects, because they won't. I'm saying it's more likely negative affects will be increased.

A plinth or chassis is a logical design for a commercial table, but it is also good at transmitting extraneous energy between platter and arm. I can't understand why you think this is desirable. Heavy pods coupled to a heavy base is more likely to resist this negative energy, depending on design.
Regards,

A plinth or chassis is a logical design for a commercial table,

And I think that just answered Lew's question why most turntable manufacturers produce the 'attached' package.
It's easy, convenient and generally 'plug'n'play'.
But this discussion really belongs on the Copernican Thread which, despite its absence from recent activity, has had nearly 1,000,000 hits so hopefully some readers are inspired to try it out...❓😎
As I repeated many times...I'm not trying to convince the sceptics here. I'm merely relaying my findings after creating the model and comparing it to all the commercial turntables I have heard and owned myself.
The only answer I could find to explain the improvements I was hearing...was the presumption that a massive level armpod was perhaps the important ingredient❓👀
I never imagined the hostility this simple mission would unleash....and all from those who have never tried it themselves...😱
Please forgive me...🙏🏽

I agree with Halcro. This latest discussion belongs on the Copernicus thread. Why Halcro's favored topology, which is not at all original to Halcro, has anything to do with Copernicus, I have never understood, but that's ok. It's catchy.

Go forth and build your pods.

Why Halcro's favored topology, which is not at all original to Halcro, has anything to do with Copernicus, I have never understood, but that's ok. It's catchy.

Now that's a good question to put to the Copernican Thread....😎

05-10-15: Richardkrebs
The linear temperature coefficient of expansion of Aluminium is 0.000023m/m degrees C and is indeed approx. double that of steel.
Using this figure on a LO7D and assuming a 5 degree C delta, we get a change in distance to spindle of around 0.04mm.

This is wrong. When examining dimensional stability one needs to take into account materials engineering. If aluminium is produced by a rolling or extrusion process, then the dimensional stability is directional - much lower along the roll and higher across the roll. Furthermore if a metal is produced by a casting process then it is usually substantially more dimensionally stable than that manufactured through a rolling/extrusion process.
The L07D is a cast foot. I think you will find the engineers went to great cost to produce a cast for this very reason.

Richardkrebs - one thing puzzles me. You made your turntable from acrylic sheet, which has a Youngs modulus 60 times lower than steel ( which means it is 60 times less rigid ) and has a temperature coefficient of expansion 6 times higher than steel. Given that your TT is a triangulated structure and the SP10 motor is mounted in the centre of the acrylic sheet, it would appear that you have mounted your SP10 motor on a trampoline. This seems at odds with your stated design goals of absolute dimensional stability.

Furthermore, on the plinth you made, the arm is mounted closer to one of the three structural legs. So not only is your TT plinth expanding and contracting at a higher rate than say a cast chassis like the Melcos & Microseikis of this world, or even the L07D, your VTA is constantly changing due to the large differential in vertical structural rigidity between the centres of gravity of the SP10 motor and the arm. In layman's terms in your plinth the SP10/platter will move up and down at a greater rate than the tonearm when excited.