Albert Porters after market panzerholz plinths

For those looking to quantify the resonance characteristics of various plinth materials, a fellow on Vinyl Engine seems to have done just that.

http://qualia.webs.com/dampingfactorvalues.htm

But wait, from his data it seems that MDF and slate measure the same, 0.017! Now I have no personal experience with comparing these two materials but I have read multiple recommendations against MDF for DD plinths (not sure why it is favored for rim-drives such as the Lenco). And I have read very favorable opinions on slate, both for commercial sources such as OMA and the DIY projects such as Lew's.

So how can it be that two materials can measure the same yet offer such varied sonic results? Were they the same overall size and thickness when measured? Were they layered or constructed in the same fashion? Or is the answer a combination of material characteristic and how the plinth is designed and assembled?

The last question seems to suggest its own answer, which brings us back to Albert's plinths.

Tim, I saw that post several months ago. The guy is somewhat of an engineer and seems to know a lot more about materials science than I do, but his conclusions don't remotely compare to my personal experience, certainly as regards MDF vs slate. In fact, it could be said that his results are proven wrong per se by anyone who has listened to plinths made of these two materials using the same turntable chassis. MDF sucks for direct-drive, IME. I owned a Jean Nantais Lenco plinth made of alternating layers of MDF and baltic birch which was excellent but not as neutral as my slate Lenco. His work did make me more curious about Panzerholz, however,which fared very well. The relationship of his test results to goodness of a plinth material could be a case of "True, True, Unrelated". Remember that choice from College Board tests?

I argued the issue with the poster. For example, I pointed out to him that the result one gets using his technique might be dependent on the orientation of the slate (parallel vs perpendicular to the layered structure) with respect to the vector direction of the stimulus and the placement of the measuring gear, but he insisted it would make no difference without offering proof. I notice that slate is kind of ring-y if struck with force perpendicular to the layers (I.e., top surface of any of my plinths) but is dead as dead can be when struck by a force parallel to its layering. Then there is the whole question of whether the results of striking any material are relevant at all to how it may perform in this application.

slate is a metamorphic rock with a highly aligned crystal structure.

I would expect different physical characteristics depending on orientation. Whether this is significant or not for this application? Who knows?

Mapman, In less sophisticated terms, that's what I said to the guy who posted those data on Vinyl Engine, to which Tim referred. He responded that orientation of the grain structure of the slate would make no difference to the outcome of his study, but he offered no relevant proof. Really, it does not matter. The very fact that MDF = slate by his method of analysis is proof to me that his method is irrelevant to the issue of what makes a good plinth. My SP10 Mk2 came to me originally in a custom-built MDF plinth; the MDF enhanced all the potential colorations inherent to the SP10 (a kind of "grayish" slightly dull coloration). In slate, and I am sure in Panzerholz too, the SP10 is transformed.

FWIW, I think the original plinth is made from obsidian, which is volcanic glass. Obsidian glass cools from lava rapidly and essentially has no crystalline structure whereas slate is a metamorphic rock formed over long periods of time under extreme heat and pressure and evidences strong alignment of crystalline molecules. So that is a very major structural difference. Does it affect the sound? Again, who knows....