Turntable lid up or off?

My forced air hvac system creates a LOT of dust, I could never leave a dust cover off when not in use.

UP, to avoid ’trapping’ and ’reflecting’ micro vibrations.

OFF, if possible, for appearance, at least for long listening sessions, I guess I would simply leave the hinged type up for single play, like I used to do with an Audio Technica I had.

In my case, the cover on the big JVC plinth is large, heavy, unattached, it must be removed. Luckily it has notches on the sides to get a good grip on it. And bimps on the plinth to align the front first, then lower without hitting anything. Very important in my situation, I have very small clearances: height and sides of 2 of my 3 arms I squeezed in there.

Notches are an advantage: not needing to reposition your hands. Off, down, lean vertically to defy gravity, back up to TT, no need to walk anywhere.

I put felt pads on the edge resting on the floor, to keep from scuffing it to hell and back, resist sliding, and isolation from floor vibrations.

When I got my SL1200G turntable, I listened both ways, with the cover open or closed using the same record.  After about 10 try’s, I found the open position better and go with that now. 

Seems a lot of higher end decks don’t come with covers so my guess is it doesn’t make a difference or better to be off. Great to keep dust off is probably all it does.

HhahahahahahaA difference in sound with the dust cover closed or removed.
SNAKE OIL!

    There is no difference.

 I have 2 SL-1200 mk2’s
one SL-1210. 
 No difference.    Just play your LP’s’ and enjoy. 
Had first SL-1200 mk2 for 30+ years. 2nd one about 5 years later.
then the SL-1210 in mid late 90’s if I remember correctly. 
    All with ortofon Arkiv and Ortofon nightclub II CONCORDE stylus.   All flawless, and no hiccups, no be,ts to tinker with.
all sound amazing.  With lid down or up,

 I can hear the cymbal and hear the drum stick hit the cymbal with the cover up, .......yeah ok....
  oh wait,....the cymbal decay is more prevalent with the cover removed as with the cover down??
ok, sure you can. 
 Just play your albums and enjoy.
don’t follow this snake oil tripe. 

VPI Classic 2  gives me  few options.  It is either on, in place, or completely off.  It is not hinged or fastened  but sits in place held by its weight. I almost always take it off.  Sometimes leave it on when rambunctious kids or dogs are visiting. 

BTW, as dust covers go, it looks OK, but has some curiously placed open spaces, like screen doors on a U-boat.  Better than nothing, but could be a tighter fit.