Originally Posted by wjr858
I understood the foam was to create a volume behind the speaker so if someone has the pdf of the SW-85s and SW-150 you could create that volume with a box in the wall lined with foam for speaker enclosures. .
Not exactly. The width between the studs and the floor to ceiling space approximates the cabinet volume. That is not overly important.
The foam behind the speaker (or you could use some fiberfill) which IS important is to absorb the back wave from the 2 5-1/4" drivers, which would tend to smear the vocal range if the back wave was allowed to bounce off the back wall, then propagate forward through the driver and into the room. This is most important with the Center channel.
Since the distance from the cone to the back wall to the cone again is about 5" (even though the cone is tapered...) that's 1/2 wavelength at about 1300 Hz. If you are feeling in an experimental mood you can test this yourself using 2 channels one with and one without the absorbtive material; just feed real mono into both speakers so the test is perfectly fair.
Also you are correct; the (rather complex) crossover arrangement is designed so that the summation lobe has a larger VERTICAL angle with the inwalls because you can't aim them and also many people put them in the wrong place, such as too high or too low.
IF you have grilles and IF you intend to paint them you must be VERY careful to NOT close up the grille holes, since the back of the grille has a cloth covering and it is very easy for the paint meniscus to fill up the small holes. The only way to paint them without filling up the holes is to use either a cloth wipe or a very good paper towel such as a bounty microwave; make a small pad, apply a very little bit of paint to the pad with a small brush, and then after the paint has been absorbed a little by the paper towel, gently dab the grille with about the size of 2 fingers.
You will soon get the hang of doing this. As you initially experiment you can wash the paint off for the first few tries. Once the cloth on the back gets wet you then have to absorb the water off the cloth with ANOTHER paper towel.
This all sounds only marginally harder than it is.
You may also elect to remove the cloth, which makes it way easier to paint, but then you see the drivers through the holes.
IF you leave the cloth in place and clog the holes that would make for a somewhat nasty attenuator...