Quote Originally Posted by Earl K View Post
@quaramon
I don't believe that for regular home HiFi the pressure ( within a box ) is an issue ( perhaps it might be at H.T. levels ).
I believe you!

FWIW, the 900 series (902, 908, 909) drivers have a rubber boot that surrounds the ferrite magnet, which then terminates ( wraps over ) the first few mm of the top plate.
- The back cap is then bolted down on to of this rubber ( which acts as a gasket of course ).
You are right, now when you mention it I remember a pair of 902 I had with that rubber surround.

We'll see, I might put a thin rubber gasket under the rear cover when I put together my 620. Non destructive and feels good......