My-O-My ! I never expected to kick up so much "dust" with my re-telling of the story of when my audio dealer dusted his turntable dust cover and created enough magnetism to alter the stylus force !
Perhaps we can end it all simply by turning our attention to another interesting thing I noticed on my 1920's Victor "Credenza". On the lowest portion of the rather sizeable and heavy lid is a decal that states, "Close Lid Whilst Playing". Since it was effectively the turntable dust cover, I hope to stay within the confines of the original post. There definitely is a difference in the quality of sound when following the directions though I've never decided whether it was a diminution of the very noticeable stylus "scratch" or a real enhancement of the sound as a result of confining the sound box to a more restrictive acoustic. Victor even encouraged the regimen of closing the lid by providing the lid with two "dashpots" which damp the lid closure enough to prevent any slamming effect. On the Columbia "360" record player from the 1950's, the edges of the lid were lined with felt so that when the lid was closed it definitely created a different acoustic situation in which the cartridge had to function. The Speakers were located on the opposite sides of the unit and one driver was purposely wired "out of phase" to create a diffusive effect. Later models of the "360", though much more modern in the cabinet design, went even more deeply into the idea of encapsulating the cartridge in its own acoustic by integrating a fully sealed plastic container within the player to isolate the cartridge even more fully than the original model. You almost have to pry the lid to open it !
My question is : Were there any modern turntables that had a dust cover/lid that was designed purposely to be closed during the play cycle to take advantage [?] of the difference between an open or closed acoustic surrounding the cartridge ? Some of us have certainly experienced acoustic feedback when positioning a loudspeaker too close to a sensitive turntable that created an acoustic feedback through the cartridge, so the reasoning follows that attention to the acoustic in which a cartridge must function is important.
I own both an early and late Columbia "360" machine and there are mono records that sound like fine stereo recordings on these machines ! Amazing !! The outer lids on both the Victrola and the Columbia "360' machines were of wood so they could not be magnetized. Thoughts ? Experiences ?