Vintage DD turntables. Are we living dangerously?

Dear Richard, For further clarification and to expound on your post above, the current Artisan Fidelity Sp10Mk2 Technics Sp10Mk2 replacement platter (~5kg.) is comprised of a magnesium alloy based lower segment and pure Copper upper section. The platter's internal cross section features concentric damping provisions to help tame stray resonances. Initially, the platters used a slightly heavier (+.4kg.) aircraft aluminum lower section but was eventually replaced by magnesium alloy possessing superior damping characteristics.

Pryso, Acute observations regarding the robustness of the factory Technics Sp10Mk2 A's DC based motor, indeed it (including supporting bearing architecture) is easily capable of accommodating a heavier platter and/or mat over stock. For reference, the factory Mk2 platter weight = 2.9kg. and a respected replacement platter mat, say for example the well known vintage Micro Seiki CU-180 weighs in around 1.4kg.

Agree and concur with numerous posters above, the Technics Sp10Mk2/Mk2A bearing structural architecture indeed can safely support the additional weight of a Micro Seiki CU-180 or the rarer CU-500 series Gunmetal Copper alloy platter mat provided the spindle's thrust pad is in good order, of course, thrust pads can also be changed and improved, if desired.  Clients have mentioned over the years rumors of Pass Labs using a Stainless Steel based replacement platter with reported success directly in place of factory Sp10Mk2 platters although I have yet to personally listen to one or actually examine one myself.  I believe it was roughly 2.5 - 3 years ago when we sat down and designed, prototyped then began to manufacture a suitable direct oem replacement Copper and Magnesium/Aluminum alloy based platter for the Technics Sp10Mk2/Mk2A models.  This is the same platter found on the AF Sp10Mk2 NG model.  If anyone is curious as to how it performs in comparison to a stock setup, please feel free to PM me directly for further insight.  As many are aware, the Sp10Mk2 design incorporates an electronic braking system, in addition to the mechanical brake belt facilities, which will tolerate the added weight of a heavy platter mat or higher mass replacement platter but the subsequent braking affect is slightly diminished in stock form.  When it comes to actual platter-to-record interfaces, naturally, each individual users system to a degree will react uniquely through difference playback characteristics, this applies when changing Sp10Mk2 platters entirely and/or platter mats and the reality is with all things high end audio related, no "one size fits all" solution exists.  This is the subjective and sometimes perplexing nature of the hobby and something I for one believe makes things all the more interesting in our niche world.   

Just for kicks, below are some additional weight specifications gathered over the years.

- Technics Sp10Mk2 Factory platter weight - 2.9kgs  = 6.4 Lbs.
- Technics Sp10Mk2 Factory Rubber Mat - .54kg = 1.2lbs
- Misc. Outer platter periphery rings - (Various manufacturers measured over the years) ranges - .5kgs - 1.4kgs / 1.1 lbs. - 3.2lbs. 
- Oyaide MJ-12 Aluminum record mat - .68 kg = 1.5lbs. 
- Artisan Fidelity Copper/Magnesium/Aluminum alloy replacement Technics Sp10Mk2/Mk2A platter - 5.4kgs = 12lbs. (designed to be used without a record mat)
- Record Clamps - too many to list - typically ranging from 6oz - 4lbs.+