Thats the first thing I realize after having them, is I whish they were closed.
There was plastic over the cups that you have to peel off, when you fist have it.
It actually simulates a closed can as it covers the grills,
but they lost a lot of bass and lower mids when playing, so you had to peel them off..
Once start pressing, it darkens slightly yet somehow retains much of the same signature.
Funny how little thw sound chages with your hands, yet with the clear plastic it totally sounds like a closed can without much bass .
This tells me that the driver only needs to breathe, and is not picky about how open the grills are (!)
Maybe with ring in between rear grill cup to extend it out a bit so as to put some dampening material and then have most of rear sealed you can attain closed status..
I am only speculating because to me it seems obvious like oppo went halfway already to design a closed can ,
But instead decided to leave it as an open can for whatever reasons..
(Like taking too long lol)
Edited by Maxx134 - 4/26/14 at 5:56pm