Hey guys,
Here's something you can try... A lot of high dollar acoustical panels from companies like Auralex can be made at home for a fraction of the price. This isn't going to do wonders for bass management, but this will greatly impact early room reflections. Try to find a dealer for Owens Corning 703, they have a dealer locater on their website. Cover that stuff with some fabric and you've got some of the best acoustic materials that can be had without paying top dollar for prefabricated items. Be careful with fabric though, you don't want something so thick that it will inhibit the ability of 703 to do it's job.
Other tips:
-A second to everyone who has stressed speaker placement. Not too close to the walls, it has a huge impact on bass response. Make sure you create a triangle between you and the speakers with all three distances being equal. Frequencies have a tendency to build up or diminish at even intervals... so placing your speakers 1/2 way, 1/4 way or any other even interval from the wall is a bad idea.
-If your room is a rectangle, then try to place your speakers so they are aiming down the long way of the room. This is going to help a lot with the accuracy of the frequency response.
-If your room is square, well...good luck!!! Parallel walls are unavoidable with the way homes are constructed, but anything you can do to break that up is good. Someone previously mentioned standing waves. Without getting too technical, this is what happens to certain frequencies when sound is able to bounce back and forth between two paralell walls. It creates a build up where some frequencies are percieved as louder, and other as percieved as quieter. If you've ever done a mix and then taken it out to your car to check and found that your bass is WAY out of whack, then you've probably discovered this.
-Also, check your mixes! Making a CD and taking it out to your car is about as good of a real world test as you're ever going to have. If you're like the average person, you listen to music in your car more than everywhere else. You know what music is supposed to sound like in your car better than anywhere else, take advantage of that! Also, checking things on a set of decent headphones or a boombox is also a good idea. Don't let yourself get too caught up in making something sound good on your speakers, it has to sound good on others as well!
Thats enough ranting from me for now!
-Marc