Alex, Sorry to contradict you, but most vintage Japanese DD turntables used light-ish platters. The most notable exception is the SP10 Mk3, which has a 21-lb platter. The Pioneer Exclusive P3 also had a fairly heavy platter, but not as heavy as that of the Mk3. On the Yamaha GT2000, there was the "GT2000X" version, which could have a gunmetal platter, probably pretty heavy, probably made by Micro-Seiki. That version also came with a heavy duty spindle and upgraded motor. The GT2000X goes for about twice the cost of a GT2000 these days, if you can find one. I guess the L07D platter is also in the category of "heavy", at about 15 lbs, with an optional peripheral ring that adds mass and inertia. I don't know where the PD444 fits in; I've never seen one in the flesh. Perhaps Chakster can comment. Other than these 4 and possibly the PD444, you would find that the platters tend to be less than 10 lbs.
The iron core motors used by many could be DC or AC synchronous types. The DP80 which has a very light platter has an iron core motor that is 3-phase AC synchronous, which affords a lot of speed stability without much servo action. But my favorite tables have coreless motors. For example, the TT101 has a lightweight platter and a coreless motor. The L07D uses a coreless motor to drive its heavier platter. I could be imagining things, but it seems to me that the tables with coreless motors are most "musical" sounding, possibly due to less or no cogging effect. I can't prove that, and I would not argue too much about it one way or the other. So I would summarize by stating that many but not all of the vintage Japanese decks are indeed like the EMT 950.
