Matt: I live in Brussels. But love the USA ( have relatives in NY ).
the PM180 fro HHall is like this: density of holes is 2.2% ( which made me conclude, given the diameter of 0.5mmm and the area formula of Pi x radius times 2 = 28,000 holes per square meter, compared to the Stewart which claims 30,000 holes per square foot; the Stewart has holes of 1/20th of an inch, which is 2.54cm divided by 20= 0.127mm if I am correct ).
So the PM180 has indeed less holes per square foot or meter and holes are more than twice as big in diameter.
The graph showing the dB loss is for an unequalized measure while the one for that Stewart is AFTER equalization a friend told me ..... http://www.avsforum.com/ubb/biggrin.gif
It seems clear however that the smaller the holes, the more you need of them as compared to less holes but bigger ones for cinema screens ( which are 1.2mm in diameter for standard viewings ( which is about 7 or 8 meters for the first row, at which distance you don't notice the holes ).
So the Harkness Hall might have almost not visibility of the 0.5mm holes but has not enough of them, compared to the Stewart, though the brightness loss is less I would guess, consequently, on this PM180 compared to the Stewart... is this clear ???? http://www.avsforum.com/ubb/smile.gif
it's a question of compromise.....;
Now, one trick is to have the left and right speakers right on the sides of the screen and just the center speaker behind it and certainly equalized but certainly too of the horn, high sensitivity type, while the Stewart can accepts standard speakers ( no horns ).