Tone Arm board material


My VPI Ares3 turntable which is made with a laminated acrylic/aluminum/acrylic plinth, about 2.5 inches thick in total, has a 5/8 inch circular cut through the top layer of acrylic which exposes the center laminate of aluminum.  Set into this circular cut out is the 'puck' arm board mounting disc which is about 7/8 inches thick acrylic.  This bolts to the aluminum via three machine bolts.  My SME Series IV magnesium tone arm is bolted to the acrylic tone arm puck.

Magnesium is known for its superior vibration and sound deadening qualities, so I was wondering if anyone has any thoughts on making the tone arm board 'puck' out of solid magnesium vs. the factory supplied acrylic??  I can see why they probably don't use magnesium as it's super expensive.  I just got a quote on a small piece of magnesium to machine a new tone arm board and its $125.  But if it were to make an improvement in performance, its cheap money.

Does anyone out there have any thoughts on this?

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OK, this is interesting; I spoke with the chief designer at Oracle Audio in Canada on this subject.  He said that my stock arm board puck on the VPI Ares3 is 1 inch thick acrylic which is a very good material.  He said Acrylic is a surprisingly good acoustic dampening medium and he suggested I stay with it.  If I go to another material, there is a risk of 'ringing'.  That will simplify my project, I can fabricate the parts I want for the VTA on the fly adjuster and bolt them to the stock arm board.
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May I suggest Corian from DuPont? It is easily machined, very stable and very inert to vibration. You can probably get a scrap from a counter fabricator for free. I’ve also made shelves for my equipment racks from Corian and wouldn’t use anything else for that. 

If all else fails, shoot for the moon and go for unobtainium! 
Multi-layer sandwich of Prosopis Kuntzei parquetry wood and piezoelectric damping material such as fo.Q TA-102 should be well worth a try. 

One other material to consider is a close cousin to acrylic---Delrin. That's a brand name I believe, not the material's generic name. Delrin is the material VPI used for the platters of the HW-19 MK.2-4, Aries 1 (top layer), and TNT (pre-Mk.6) tables. It is a little denser and harder than acrylic, and has a matte sheen in contrast to the high gloss of acrylic. I had an acrylic arm board for my Aries 1 made at a good plastics supply house, and the price for a Delrin version was only slightly higher than for the acrylic.

Another option to consider is to have two 1/2" thick boards made, with a thin piece of constrained layer damping placed between them, for damping of any ringing in the material.