http://www.termpro.com/programs/archive.html
That link will have a menu of free downloadable programs, many for designing loudspeakers, however there is one for speaker placement. That link is from georgia audio labs at www.audiolabga.com
Quick guidelines, make sure the distances from the back wall and side wall near the speaker are not the same. Keep at least 6 feet between the speakers. Try to get a minimum of 2 feet, preferable more, from sidewall, same applies to back wall. As far as listening wall, where your sitting, stay out from the rear (listening) wall several feet (although one school of though recommends being flat against the listening (rear) wall, this is debatable. My setup is like this by no choice of my own, it'll certainly give you low end reinforcement-I don't recommend it). Get a more or less equalateral trianlge between the speakers and you. You may end up sitting a little closer, or a little farther away. Have speakers firing straight ahead, from there experiment with slight toeing in. (There are other extreme methods of having the speakers pointing directly at the listner or even crossing thier axis somewhere in front of the listeners face --I would avoid those). Take all measurements from the midpoint of the front edge of the speaker cabinet (this is where the sound is coming from). If its a time aligned designed approximate the midpoint somewhere in the middle of the axis slope where all the drivers from are from an aerial view, you're trying to find the point at which all the voice coils are lined up.
Positioning for dipolars, bipolars, electrostats, certian horn designs, and any other design with some peculiarities, such as NHT's big speakers, need to go by certian rules specific to that design.
For that glass window, Some nice vertical blinds might help diffuse the highs when slanted (hey they're tunable) short of resorting to impractical methods (like covering the window with foam). Paintings, wall hangings, tapestries, other stuff help absorb and diffuse sound so if done properly you shouldn't need acoustic treatment. Should you opt for, basic foam at the first reflection points on the sidewalls are most important, i.e. the point where if you placed a mirror on the sidewall you could see the tweeter from the listening position, it won't be halfway, closer to the speaker. Second most important area is the wall directly between the speakers on the back wall. Third is the listening wall directly behind the listeners head. Those are the areas to treat with home stuff if possible. If resorting to foams, 2" at those points is good. The following links are good places:
www.auralex.com
www.silentsource.com
www.echobusters.com
And then RPG and ASC (www.tubetrap.com?) have websites too.
If you go homebrew, jon risch has some ok designs. Bass traps probably aren't necessary although maybe. Do not use the "eggcrate" foam designed for your bed. Its absorbtion nrc. measurements are horrible (like .40) its ugly, and for what you paid for it you might as well have bought a basic package of acoustic foam that will do the job right without having to cover as much of the wall. The rpg starter kit is ok, it used to be a good deal when it was $50, now its up to $75 but still maybe the easiest thing to do. Look around though.
my 2 cents.
