plinth for tts8000

Back when I undertook to make a slate plinth, it was originally for my Lenco, only.  This must have been at least 15 years ago, and there was a "thing" going on about slate plinths, over on Lenco Lovers, or whatever the website is called. OMA made a slate plinth for the Lenco L75, but it was too expensive for me, so I decided to make one of my own.  That's how it all started, just out of my own curiosity. Like I hope I said, I don't ascribe any magical properties to slate except to say I liked the results with the Lenco, and by that time I had identified reliable sources for PA slate (the same slate that OMA uses; apparently slate color and character can vary according to geography) and for water-jet cutting of the slate, so going forward from there was only a matter of locating pdf files that could be used to program the water-jet. (For this work, I thank the guys at RC Waterjet in York.  They were great.)  Peter Reinders, a very nice guy on Lenco Lovers, was able to provide the pdf file for cutting the Lenco slate.  I got the files for the SP10s off another website (Soundfountain).  We created a file for the DP80, using the measurements off the actual chassis.  I made an engineering drawing, and the waterjet guys turned my drawing into a pdf. It was no problem at all to acquire slate slabs cut to my specs by the quarry in PA.  Furthermore they honed both sides to perfect plane flatness and champhered the corners of the slabs, for looks and so they weren't dangerous to handle, before sending to the waterjet company.
Mijostyn, You may be correct that torque is a problem only at start-up, but there is such a thing as stylus drag, which also requires momentary bursts of torque from the motor, to maintain absolute constant speed. I think it may be important to hold all surrounding structures, including the stators, rock stable against the torque that can be supplied by the motor, so all that force (=torque) is devoted to accelerating the platter.  It just seems a good idea.   Richard Krebs devoted a lot of study and analysis to this issue with respect first to the SP10s and then to his own tt design, which I think is now commercially available.  He offers mods to SP10 Mk2 and Mk3, to stabilize the stators on those two turntables.  I've had that mod applied to my Mk3, and I believe I can hear a difference; the modified Mk3 is more "musical", flowing, effortless.  (Not very scientific, I admit.) Because the Mk3 motor is more torque-y perhaps than any other DD motor ever sold commercially, the benefits of the Krebs mod may be most obvious on the Mk3.  Also, Technics opted for tight servo control. Some other DDs, e.g., my Kenwood L07D use a more relaxed servo feedback system, and indeed the L07D is exceptionally musical and flowing in its SQ, as is. Not to mention it also has a coreless motor, also a good thing. (We agree, Artemis.)

best-groove, Perhaps the WT turntable sounds good in your system.  I have a history of finding fault with the WT tonearm. I won't reiterate here.
Artemus, You wrote, "However After doing a lot of testing with various footer materials, there are materials like glass, Metals & Stone which raise red flags to me."  By this do you mean to say that based on your experiments with footers, you question the use of slate as a material for a plinth?  Because for one thing, I don't use slate footers on any turntable.  For another, I think it is misleading to lump all sorts of materials we take out of the ground under the term "stone", if that was your intent.  I don't care for granite or marble used as shelving or plinth-making.  Slate is quite different from those two in that it is naturally layered, which is why it is so difficult to cut and shape; it can fall apart if you are not careful.  We destroyed some slate slabs on the water-jet machine until the guys in York figured out how to cut it without fracturing it.  To quote from Wiki:

"Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression."

It is those planes perpendicular to the compressive force present when slate was formed that I think makes slate a good material for dissipating energy, and why it does not ring, as other "stones" may do. But I am not here to argue one way or another.  I can only say I like the results.

Mijostyn, I did not think we were talking about suspending a turntable, or not.  I am all for a good suspension and totally against a poorly thought out suspension. The only really good one I know about is the Minus K. I do not think built-in suspensions where one has to choose between suspending the motor along with the platter and bearing, where motor vibrations are not isolated from the platter except by the belt, or not suspending the motor, where the belt must be allowed to flex in order to accommodate any motion of the suspension relative to the motor, in which case one invites speed irregularity due to belt stretching and contracting. I don't know how to solve this dilemma, so I live with no suspension and high mass.  Moreover, high mass is advantageous for DD turntables, at least. Not because it affords isolation so much as it does afford a high mass for the high torque motors to work against, lest the plinth moves instead of the platter. Newton, again.  For this very reason also, it is problematic to suspend a DD turntable.  But you dislike DD, so no problem for you.

I actually made, or had made for me, slate-based plinths for the DP80, the Lenco idler, and the SP10 Mk3.  Before that, I also made a slate plinth for an SP10 Mk2, now sold along with the Mk2.  These projects were done one by one, not all at the same time. I purchased slate slabs cut to my specifications from a quarry in PA.  (Details available upon request.) I then identified a water-jet company in York, PA, who did all the cutting for me and helped with programming their machine to make the precision cuts required to accommodate this or that turntable chassis.  After that, I drilled the holes for tt chassis mounting bolts and tonearm mounting, myself.  (Except for the Mk3 plinth, I did not create conventional removable tonearm mounts; the tonearms mount directly on the top surface of the slate slabs that act as plinth.  This was to save effort and also for structural reasons.) All this required a lot of driving back and forth to PA from my home in MD, and a lot of work in my garage.  I must have been obsessed back then; I don't think I have the energy or the enthusiasm to take on such projects these days.

Slate seems to work very well as a plinth, but in the case of the SP10 Mk3, I also added a massive wood base made of solid Cherrywood.  It is my subjective impression that the wood base made the SP10 sound even more neutral than it already did using slate alone.  The SP10 Mk3 plinth in total weighs close to 100 lbs. So I believe there is some real benefit to the CLD approach.  In the case of the OP, I would suggest you consider putting the aluminum layer in between the two layers of different woods.  That might provide a better CLD effect than stacking two kinds of wood with alu underneath.  But really, who knows?  Just my guess.  One thing I do believe: MDF is never the best choice for a TT plinth.