On Thursday, November 10, 2016 at 3:29:19 PM UTC-5, Jon Elson wrote:

Oh, boy! Did you see how HIGH they levitate the platter? Geez, I have
strong doubts it can be stable at that height. Also, the thing must have an
insanely strong external magnetic field.

Now, the only way I know one-sided levitation at low speeds can work is with
something that TOTALLY excludes flux lines, ie. a superconductor.

https://en.wikipedia.org/wiki/Neodymium_magnet

I have experienced these magnets directly - when we were in China, the novelty shops sold a device with what amounted to a metal puck, about the size of a hockey puck but half the thickness that could be suspended above a platform if "heads" or was very nearly impossible to remove from the platform except by sliding if "tails". Variations included a shaft that could be spun in suspension over a bed attached to the platform and another that could be twirled.

When we tried to bring it back to the US in our checked baggage, we were called to the front of the plane and informed that these things were powerful enough to interfere with aircraft navigation systems - and that we would have to either get off the aircraft and mail it, or give it up. We gave it up.

In any case, I would have no difficulty at all believing Neodymium magnets within the platter with a rotating field developed in the plinth reaching that distance. And, it would have the additional effect of 'centering' the platter as well. The platter *will* be quite heavy.

Now, one more beneficial effect of this system: The field will be, effectively, two nested donuts, and they could be rather small relative to the 12" platter given the power of the static field (in the platter) - perhaps as little/small as 6". At that size, the platter would be a shield for the cartridge both magnetically and in rF. Note that the cartridge is always *ABOVE* the field with the platter between it and that field.

Not that I am going to line up to purchase that TT. I am hooked on linear tracking arms - and unless/until that happens, it is only a neat trick, no more.

Peter Wieck
Melrose Park, PA