SP10 Mk II vs Mk III

Hello Lewm,

I've been a silent reader for a while... Thanks for the question. And yes, that's the material. It is available in different hardnesses-densities (the densest the harder).
My idea is to use it along with plywood using a very thick slab (about 2') in the middle of the "sandwich", in this way it will be protected, add mass with a diffrent resonace curve, and a quite dead material halfway. That slab will be also used as the base for the armboards (to be done from thick blocks of the same material, that i know is good for the purpose since i am already using it).

To further add mass I tought to make a bottom steel plate "a la" Porter, only I tought to make it bigger so that all the screws of the motor unit will go there. The "screws" will be made out of 1' brass (or steel?) tubes worked at both ends.

Now a few questions, one for Mr. Albert Porter (by chance we are colleagues... funny). Is it there any special warning/advice he can give about the center "screw"? You remove a cup and go in with the screw... but what's there (i am still waiting my unit..)?
The second question is more general. I plan to make those 6 big screws that will pass trough all the plinth and reach the bottom steel plate. Should those screws and the bottom plate have a rigid coupling to the whole structure, or should them (and the plate as well) be decoupled somehow (using a layer of neoprene around the tubes and over the plate)?

...ummm maybe this reading is too difficult (english is not my language, also), is it there a way to post some sketches here?

Well, as usual many thanks to everybody here... all informations and ideas are precious!

Silverprint, Don't know what Albert is going to say, but in general it is not a good idea to decouple the tt and the plinth. The whole idea is to couple them as efficiently and completely as possible. Rubber grommets or any similar devices will defeat the purpose. As far as your plinth idea, I think it has real possibilities. Where and how have you got hold of thick pieces of graphite and the ability to machine them?

Now a few questions, one for Mr. Albert Porter (by chance we are colleagues... funny). Is it there any special warning/advice he can give about the center "screw"? You remove a cup and go in with the screw... but what's there (i am still waiting my unit..)?

I don't know of a center screw, only the brass rod that contact's the Technics bearing cup to drain. Nothing in my design penetrates the Technics in any way. The screws we choose go from the plinth bottom and into the factory tapped holes. Screws are original thread and non magnetic stainless steel.

Hello Lewm and Albert and Many thanks.

Albert, I probably misunderstood when reading of your plinth on sound fountain, it seemed to me you put the rod in place of the bearing cup, working its end to suit, and felt a bit afraid of going in such mod. Having a rod touching it (with some pressure?) is easyier and safe. Thanks.

In fact Lewm answer was necessary and obvious (it appeared to my mind a couple of hours after posting...) I was so lost in finding a good way to organize the layers that I missed the point!

The graphite market is increasing for various different uses, metallury, batteries, chips (!) so there are many businesses around, big and small where the material is available. It is enough to have a look out of the audio market. Graphite is not exactlly cheap, but it seems that those company making audio products out of it are decuplicating the price of the material (at least...). I get mine from a friend in Rome, he's running a small business of fairly priced graphite audio pruducts and can cnc machine any sort of piece.
But I guess this info is not of much use: if you start shipping heavy manufacts overseas you'll probably loose the good price, I would have a look around searching for small companies selling graphite there in the US, they will very luckily have a cnc machine at hand and hopefully be willing to make a few pieces on design.
But... well, in case your planning a trip to Rome, bringing back some pieces (small) can be done!

Dear Silverprint, I doubt that "decuplicating" is a word in English, but it is a very good invention, and the meaning is obvious. Yes, there is a lot of decuplicating going on in the computation of the prices of audio products that derive from materials used in other applications. Sad but true.