Vintage DD turntables. Are we living dangerously?

Lew, The Resomat is almost weightless. It consists of a paper-thin acetate sheet that serves only to fix the locations of the small and lightweight vinyl acetate cones that couple the record through the sheet to the OEM platter. The cones pass through the sheet and their bases rest directly on the TT platter. So the idea with this mat is not to isolate the LP from the platter, but rather to couple it at two radiuses. The mat is available in several versions: short cones or long cones designed to clear the raised lip of an SP-10 platter.

With L07D I'm using a sandwich arrangement. Stillpoints LPI record weight over short-point version of Resomat over TTW Weights 4 lb./4mm solid copper platter over ERS cloth mat over Kenwood steel plate. The Kenwood's tall spindle is just long enough for all of this.

The weight of the copper mat is pretty close to the weight of an original Kenwood perimeter ring. The performance with the copper mat is improved by pressing the button on the L07D PS that was conceived for the perimeter ring.

Jcarr, very helpful & thank you for the info.

Interesting to consider torque to mass ratio with the Yamaha GT 2000. Stock platter was 5.8kg. Optional platter was 18kg and was used w/o modification. That's almost 40lb. The Goldmund Reference platter was 35lb, was said to be too heavy for a DD table.

Fleib, I have seen a lot of GT2000s, both in person whilst in various Tokyo audio emporia and on the internet. The ones I have seen all seem to have a relatively "thick" platter, due to peripheral rim thickness more than anything else, but I don't know whether I am looking at the 5.8kg standard or the 18kg optional. Did you find a photo of the latter? That's a huge difference in platter mass for use on the very same motor with the same servo feedback mechanism, unless the motor/servo is switchable so as to accommodate the heavy platter. As Dave mentioned, the L07D power supply does have such a switchable mechanism, to be used when one is using their dedicated record weight and peripheral ring (and in Dave's case, he uses it with his complex platter "sandwich").

WRT your discussion with Halcro re the LP/platter interface, I would say you're both correct. The nature of the interface is "understood", but there is no agreement how best to deal with it in order to achieve max fidelity of sound reproduction.

Lew,
There are photos of both the GT2000 and 2000x at Vintage Knob. Stock aluminum platter is pretty hefty at nearly 13 lbs. The x platter looks similar, but is gun-metal. The motor shaft on the x is beefed up to 6cm vs 2cm for the 2000, but apparently the rest of the motor was the same.
The heavy platter was an option on the 2000 so I guess the shaft could handle the weight.

How do you think these Yamaha's stack up?

Fleib
How do you think these Yamaha's stack up?

There certainly are many GT-2000 owners about, as to how they
stack up there was a thread that Jcarr posted regarding a {Japan forum} where a Victor motor designer who had a hand in the GT2000 design pursued the Yamaha and ended up taking it home.

I thought it a rather fitting endorsement.

Found it
Jcarr
There is an interesting Japanese webpage by a retired JVC engineer, in which he talks about his involvement in designing the motor drive and controller circuits for the slotless DD motor of Yamaha's GT-2000.

note, several pages
http://37282.diarynote.jp/200708032337340000/