Best Subwoofer Placement
You're wondering what is the best subwoofer placement to get the most and cleanest low frequency output for your home theater. Locating your subwoofer within your listening area is critical in order to get the best response from your sub.

There is no absolute best location.
Subwoofers work very well in a variety of locations -- however, the physical placement of a sub in your listening room will affect its overall performance. Since the wavelengths of sound reproduced by your subwoofer are large and long compared to the physical size of the enclosure, those low frequncies are omni-directional in nature. This means that locating your subwoofer in relation to your left and right main speakers should not affect the directional cues which they provide. If you can close your eyes and point to where you are hearing the low frequency effects coming from then you need to re-locate your sub.

The audio you hear is a combination of direct sound from the speaker and reflections from the walls, ceiling, and floor of your room. Placement of your subwoofer in relation to your theater room walls affects the balance of what you hear at low frequencies. In low frequency ranges, the dimensions of most home theater rooms are comparable to the wavelengths (or frequencies) of those sounds. As sound waves reflect and bounce within the room, “standing waves” are created at frequencies where the wavelength of sound or multiples of the wavelength are equal to one of the room measurements. At the main seating area, these standing wave patterns of reflected sound are added together -- in and out of phase -- causing variations in the frequency responses that you hear.

As a general rule, locating your subwoofer near the corner of a room will increase its overall perceived output, but will induce more standing waves within the room and may result in more uneven low frequency effects response. Locating your subwoofer along a wall will usually mean less perceived output but with a somewhat smoother response. A middle of the room location will produce the smoothest overall response but with the least acoustic output capability.

One technique for finding your best subwoofer placement is to "trade places" with it. Place your sub in your normal listening position -- on your chair or couch at ear level -- with it playing bass intensive media and then search for the spot(s) in your room (on your knees with your head at just above floor level) where the bass sounds more pronounced. This unconventional technique is best performed alone so as not to draw strange looks and comments regarding your level of sanity from family and friends. ;)

Of course, any location will be a compromise and a trade-off between the acoustic performance and the aesthetic looks of the sub enclosure while blended with the decor of your room. You should experiment with the location of your subwoofer in your theater room for the best results at your main seating area. Move your subwoofer around a few times until you find the best subwoofer placement that satisfies your ears and blends well with your room decor.