Quote Originally Posted by microstrip View Post
My comment was triggered by your introduction - Since we are in Science here and then just adding a commonly known and reported fact, fully ignoring the hard science part. Most probably people will easily ear effects due to different platter materials due to the mechanical characteristics - it is known since long that they are above reliable audibility thresholds.

However "Lenz science" will prove that due to the steady magnetic condition of the platter - when rotating a non magnetized platter with cylindrical symmetry will keep always the same equivalent position relative to the stylus - there will be no change in the EMF generated or force applied to the cartridge. It is like dropping the magnet in a longitudinally slotted tube.

Magnetic platters will simply change tracking force, with harmonic non linear dependencies on position.

Curiously the original Ack post link has a warning that has been ignored - Unfortunately there seems to be no concensus on how significant the effect of stylus damping is, or even whether or not stylus damping is a good or bad thing.

Pseudo science - that in audio usually takes the nice name of non quantified - is a dangerous game. Usually it picks a small effect in the middle of an ignored large effect and tries to justify the differences with the small effect.
Its actually an interesting question...

If the platter were magnetic e.g. iron casting then the rotation would induce a current in the coils of the cartridge, though as not well aligned with the field very weak, as well as pull on the cartridge changing vtf, this is well known in the original thorens 124 platter and why they changed to aluminium top platter in 124 mkII
http://www.schopper.ch/index.php?page=non-mac-platter

The magnetic field in cartridge would induce a magnetic field in paramagnetic platter e.g. aluminium/magnesium, and pull it towards each other

although it will effect vtf, though obviously it is static if the platter is of uniform purity, and harmonic if not

If it were made of carbon/copper then the rotation would induce levitating magnetic field(diamagnetic), but this is so weak i think in everyday matters not important