Of course if you could get the temperature low enough you could use a
superconducting magnet and lose no power so no stray fields.
Brian

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"Graeme Wall" wrote in message
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On 02/07/2017 10:00, Phil Allison wrote:
Graeme Wall wrote:

------------------------



Only 12W of power consumption and the TT floats & rotates 50mm above
the base.


If they can do it with trains, a turntable shouldn't be that difficult.



** Answers nothing.

When you take into account the puny power consumption, 50mm of lift that
disappears when the power goes off PLUS and that a magnetic phono PU must
not be upset by strong or rapidly varying mag fields - it looks an
impossible task.

But pictures like the ones I linked don't lie.


One of the things I learnt early on was that pictures nearly always lie
:-)


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Graeme Wall
This account not read.

Brian Gaff wrote:

-----------------------

Of course if you could get the temperature low enough you could use a
superconducting magnet and lose no power so no stray fields.
Brian


**From a similar thread on RAP:

-----------------------------------------------------------------

On Sunday, July 2, 2017 at 9:10:37 PM UTC+10, Mike Rivers wrote:


And the levitation and rotation is achieved how ?


Permanent magnets. It runs. It plays records. I saw one at CES this
year. I think it's more for amazing and amusing your friends than for
being a superior way to play records, though I expect that the isolation
from vibration is excellent. Just the thing for playing your old Bob
Dylan or Aerosmith LPs during an earthquake.

---------------------------------------------------------------


** Mike Rivers is a credible enough guy.

So as expected, is uses powerful ( likely Neodymium ) magnets.

There has to be a second rotating table under the main one, out of sight.



..... Phil

In article , Phil
Allison wrote:


** Mike Rivers is a credible enough guy.

So as expected, is uses powerful ( likely Neodymium ) magnets.

There has to be a second rotating table under the main one, out of
sight.

My curiosity is WRT the level of field the cartridge is exposed to, and
what effect that might have.

Jim

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On Sun, 2 Jul 2017 04:32:16 -0700 (PDT), Phil Allison
wrote:

Brian Gaff wrote:

-----------------------

Of course if you could get the temperature low enough you could use a
superconducting magnet and lose no power so no stray fields.
Brian


**From a similar thread on RAP:

-----------------------------------------------------------------

On Sunday, July 2, 2017 at 9:10:37 PM UTC+10, Mike Rivers wrote:


And the levitation and rotation is achieved how ?


Permanent magnets. It runs. It plays records. I saw one at CES this
year. I think it's more for amazing and amusing your friends than for
being a superior way to play records, though I expect that the isolation
from vibration is excellent. Just the thing for playing your old Bob
Dylan or Aerosmith LPs during an earthquake.

---------------------------------------------------------------


** Mike Rivers is a credible enough guy.

So as expected, is uses powerful ( likely Neodymium ) magnets.

There has to be a second rotating table under the main one, out of sight.

You could do it with something like the stator coils of a dc motor.
Whatever - I'm guessing that the local magnetic environment is nasty
enough that your choice of pickups is pretty limited.

d

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Jim Lesurf wrote:

--------------------



** Mike Rivers is a credible enough guy.

So as expected, is uses powerful ( likely Neodymium ) magnets.

There has to be a second rotating table under the main one, out of
sight.

My curiosity is WRT the level of field the cartridge is exposed to, and
what effect that might have.


** Lotsa folk have though of that - hence one hears remarks about using a crystal PU.

Many things are not speced, like W&F, so it is no surprise that the mag field above the platter is not either.



..... Phil