From:
http://www.polkaudio.com/home/faqad/advice.php?article=subsetupPut Your Subwoofer Where It Counts
Subwoofer Placement and Adjustment for Better Performance from The Speaker Specialist, Issue 3 by Paul DiComo, Richard Hardesty and Robert Harley
In issue #2 we explored various hook up options for subwoofers, and (happily) got many calls and emails from readers reporting improved performance based on our advice. In this issue we'll discuss how to find the right placement and settings for your subwoofer. To help make this article as helpful as possible, we called on two leading audio experts for help-Richard Hardesty and Robert Harley. We'll be quoting from Harley's book and Hardesty's Audio Perfectionist Journal throughout this article and otherwise shamelessly stealing their suggestions. Their contributions to making this a better article are simply enormous. (Thanks guys!)
Before we begin, let us give you a few warnings.
1 The methods here will help get you the most accurate bass. If your goal is strictly maximum "slamitude," just stick your sub in the corner, turn up all the knobs and have fun.
2 Finding the perfect settings and location takes time. If you have low tolerance for moving speakers and twiddling with your audio gear, quit reading now. But realize that you're missing a few simple techniques by which you may be able to greatly improve the sound of your system.
3 Let your ear be the final judge. We'll give you some techniques and advice, but the science of room acoustics is so complex it defies easy answers.
The Goal
"It's relatively easy to put a subwoofer into your system and hear more bass. What's difficult is making the subwoofer's bass integrate with the sound of your main speakers
A well-integrated subwoofer produces a seamless sound, no boomy thump, and natural reproduction of music. A poorly integrated subwoofer will sound thick, heavy boomy, and unnatural, calling attention to the fact that you have smaller speakers reproducing the frequency spectrum from the midrange up, and the big subwoofer putting out low bass."1
PositioningRoom acoustics have an enormous impact on the sound of speakers, including subwoofers. A phenomenon called "standing waves" makes bass response uneven from place to place in your room. To experience this for yourself, put on a CD with a strong, consistent bass line. Notice how the volume of the bass goes up and down as you move around the room. Stand in one place and then squat down-you will probably notice that the bass changes in the vertical plane as well!
Because the subwoofer's location affects how standing waves are created, the first step to getting accurate bass response is finding the right spots for your subwoofer and your listening position. We'll share a few guidelines that may be helpful, but in the long run nothing beats trial, error and your own two ears.
Stick It In The Corner-This is the advice most often given and it certainly will yield loud bass. But corner mounting may make the woofer sound "one note-ey," and boomy on music. If lack of bass volume is your biggest subwoofer problem, this may be the answer for you.
Avoid Sitting Up Against the Wall-Bass waves build up and "hang out" at room boundaries (walls). Your system will sound thick and heavy when your listening chair is up against a wall. If you must sit against the wall because of furniture layout, place your subwoofer away from walls and corners.
Avoid Symmetrical Placement- "Avoid putting the subwoofer the same distance from two walls. For example, if you have a 20' wide room, don't put the subwoofer 10' from each wall. Similarly, don't put the subwoofer near a corner and equidistant from the side and rear walls. Instead, stagger the distances to each wall."1
Put The Subwoofer As Close To The Main Speakers As Possible-Even though bass sounds are non-localizable, cabinet resonance and other factors conspire to make this less true in practice than in theory. It'll be much easier to get seamless blending between sub and main speakers if they are on the same side of the room. If possible, put the subwoofer behind the plane of the main speakers. At very least, keep the subwoofer in the front half of the room.
Here's An Old Trick-Put your woofer in the same spot as your listening position. It's best to raise the subwoofer off the ground to seated ear height (use a sturdy, non-resonant platform). "
Play a piece of music with an ascending and descending bass line such as a 'walking' bass in straight-ahead jazz [see recording suggestions]. Crawl around the floor on your hands and knees
until you find the spot where the bass sounds smoothest, and where each bass note has about the same volume and clarity. Avoid positions where some notes 'hang' longer and/or sound slower or thicker than others.
When you've determined where the bass sounds best, put the subwoofer there."1 Use Two Subwoofers-Using two asymmetrically placed subs will minimize the effects of standing waves in your room, yielding smoother bass response (as well as better dynamic range). But don't run out and buy another sub just yet. Get the sub you have now to sound its best before spending more money. You may be perfectly happy with just one sub once you've tried our suggestions.
One Note Of Caution-
Few subwoofers are magnetically shielded (exceptions include Polk PSW250, 300, 350, 450, and RMDS-1 subwoofers) and may damage your TV if placed too close to the set. Select an unused video input on your TV to bring up a single color screen. If you see any color distortion anywhere on the screen, an unshielded speaker is too close to the set and should be moved away from the TV until the color distortion disappears.
