Halcro.
We are both blessed with having music rooms that have concrete floors sitting on mother earth.
My definition of a plinth is likely a little wider than yours. To me it is.. "the structure that maintains accurate dimensional stability between the record surface and the tonearm". I am sure that you will agree that dimensional stability in this area is critical. I have also called this structure a "loop" in an earlier post.
By that definition your very nicely built stainless steel motor support, the shelf(or floor) and the equally nice arm pod are all parts of the plinth.
It would be reasonable to expect a change in the sound, if you were to change the stainless steel support for say a large diameter cardboard tube. Likewise we could expect a change in sound if the arm pod was made from say balsa wood. I suspect that your choice of these materials was based on experience and sound logic.
Since substitution of different materials would likely alter the performance, it can be inferred that your "plinth" does have a sound.
We are both blessed with having music rooms that have concrete floors sitting on mother earth.
My definition of a plinth is likely a little wider than yours. To me it is.. "the structure that maintains accurate dimensional stability between the record surface and the tonearm". I am sure that you will agree that dimensional stability in this area is critical. I have also called this structure a "loop" in an earlier post.
By that definition your very nicely built stainless steel motor support, the shelf(or floor) and the equally nice arm pod are all parts of the plinth.
It would be reasonable to expect a change in the sound, if you were to change the stainless steel support for say a large diameter cardboard tube. Likewise we could expect a change in sound if the arm pod was made from say balsa wood. I suspect that your choice of these materials was based on experience and sound logic.
Since substitution of different materials would likely alter the performance, it can be inferred that your "plinth" does have a sound.