Mario,
Talking about outside the box ideas is my forte. Thanks for reminding me about how the thread started, though. Bear in mind that we are talking about DIY things, so I see the discussion of slate to be appropriate, and just because someone embarks upon an expansive project doesn't mean that nothing is to be discovered by those who are not so inclined. Nothing is created from a vacuum; things all start someplace, and sometimes that someplace is an esoteric one. You can do almost anything on the cheap, if you set your mind to it.
That said...
I'll take it line by line.
"The issue is not whether or not slate has internal resonances, but whether or not slate can draw away and kill noise from the 'table as effectively as a wooden plinth, and even if so, without recourse to extremely expensive/time-consuming procedures."
I placed a Litman pediatric stethoscope directly on slate within one centimeter of a mounted motor, and heard no noise. Try that with wood.
"Slate may have no internal resonances (I'll find out), but it is the metal of the top-plate - regular or Reinderspeter - vibrating against the slate, a hard surface - which will cause noise/resonances in the metal itself, without being drawn away, to cause problems."
Everything in the physical world has resonances of some sort. Whether one would hear noise from a top plate would depend entirely upon the construction techniques used, or lack thereof. Wood is much more problematic in that regard, as many know.
"There are no perfect surfaces. Imagine metal hitting wood: you get a dull thud. Imagine metal hitting stone: it sets up a high-frequency ringing."
How is relevant in any context applicable to turntable construction? It isn't. "Direct Coupling" should handle that hurdle, right? LOL
"Which is why I referred earlier to the ceramic ball phenomenon: an extremely hard material (harder than metal), which seemed like a good idea, but which in the end fabricated the illusion of increased detail rather than its reality (the metal-to-ceramic created a disparate-material barrier which filtered out the bass frequencies in order to unnaturally highlight midrange and high frequencies)."
This is totally application dependent, and apples and oranges when used in a discussion about slate. There is no correlation at all. Further, it simply is not true. What it may do is emphasize the inadequacies of a given platter, or other component, or not. More likely is that the surfaces are incompatible due to lack of research of the builder. Ceramics are designed to run on certain surfaces, but not all. Google is your friend on this point.
mosin
