I don’t want to make a box like I did for the Beyma slot loaded super-tweeter, ‘cause I sorta like just having/seeing the Heil sitting on top.
The front is protected by the front grill. So as a temp-try I’ve just taped a bit of open foam in the back and on top to the front grill. It needs work. Another idea is to make a sock from a pair of my wife’s black pantyhose stockings ???
I guess I never gave any thoughts to dust protection on these. Is it pretty necessary, do you think?
We have our windows open most of the summer months and it’s dusty (gravel / dirt driveway) doesn’t help. Or I guess I could just play them louder 
I was thinking I could use a can of keyboard air to gently blow them off once in a while- but the way they are made it would just (possibly?) blow the dust further into the unit.
Now I’m paranoid. I have a build planned using these.
Leave them open air and use an upholstery vacuum brush to remove the dust - this way the vacuum pressure will be reduced through the soft bristles and still remove the dust - touch-up with a soft damp cloth as needed for visual appearance.
The Heil’s diaphragms are well protected due to their inherent construction.
Pantyhose will roll the top end off. If you find my post on my install in my G35, I did a test on that over the BG neo8s
Daily dose of some Van Halen eruption should do the trick 
That 
is some of the most viscerally sensual data I have ever seen!
Stockings smooth the Freq response exactly as they do to a woman’s’ hairy prickly legs . . .
Interesting, although I’m guessing a ribbon / planar magnetic would be, in addition to the translucent value of the material, also (and expectedly more so) affect the movement due to the air pressure. I.e. thinking the ribbon design being more sensitive than the accordion design of the Heils. Was your test / measurement done with the stocking material up against the plate, or was the material a bit away from the front plate- hence a measurement of the translucency of the material alone, or in combination with the restrictive air with the material up against the plate?
Are we about to embark upon the mathematical/graphical expression for a “Standard Queef”?
For my situation, these were all done stretched across the front of the driver.
FY it’s worth, I measured from at about 4 inches from the driver w/o grill, with grill (std grill cloth), and out the back with the open cell material (used as dust protection). The accordion/driver section of the Heil is about 2 ¼ in from the front of the unit, which then is about ⅛ to ¼ from the grill. On the back the open cell material is approximately 1 ⅛ inch from the driver. The with vs w/o front grill is a fairly consistent 1 dB difference starting at ~ 1500Hz (below which they are on top of each other). So very consistent across frequency band, and manageable when developing Xover and eq.
The back (open cell foam) measurement shows a bit of a drop above 16g, yet more transparent below 1g ? More than likely the mic was positioned a bit closer when I measured from the backside.
