We've mentioned some speaker placement rules for achieving optimal sound before, but the subwoofer can be a different beast altogether. Weblog Audioholics recommends a technique called the "subwoofer crawl" to find the perfect spot in your room for full-sounding bass.
If you've set up your speakers but find the bass doesn't sound very good (maybe its isn't very smooth, or maybe you just can't hear it at all), there's an easy way to find the best place to put your subwoofer. Start by placing your subwoofer in the spot where you usually sit when watching movies or listening to music, and turning on a fairly bass-heavy test track. Then, crawl around on the floor and listen to where the bass sounds the best — you're looking for deep, smooth bass, not loud and rattling. When you find a spot that sounds good (and where you think your subwoofer will fit in with the furniture), switch spots with your subwoofer — it should sound about the same.
The reason you crawl on the floor is because you want it to hear what it sounds like at the same height you'll hear it when you're sitting down. If you walk around the room upright, you'll hear it differently than you would when you're sitting on your couch, and you might put it in the wrong spot. It's a pretty neat trick, and nice if you're noticing your bass is less than ideal. Hit the link to read more.Photo by laffy4k.