Whether you already own a killer subwoofer or are in the market for a brand new beast, knowing where and how to place it is arguably the most important decision. Yes, subwoofer placement is a big subject. Most down firing subwoofers are placed on softer surfaces such as carpet. https://www.audioholics.com/subwoofer-setup/easy-subwoofer-placement You could have a couple of brand new, custom made 12-inch subs but without taking advantage of the space available, you will never maximize your audio potential. An alternative is to buy a wireless sub. Put the subwoofer right up where you sit and turn on some bass-heavy music (or a bass-heavy movie soundtrack). Walk around the room until you find the place where the bass sounds best. If your subwoofer is a port design, it’ll have a small hole in the back to allow air to flow through. If you have a wired subwoofer, look for the best place without leaving any wires for people to trip over. Although carpet will absorb some of the sound, it is better to place the down fire on carpet than it is on hard, smooth surfaces, as these will reflect sound directly and cause a boomy listening experience that can be fairly unpleasant. One good way of finding a place for your subwoofer is to swap places with it. Pre-determining where a subwoofer should go, using some byzantine mathematical formula or between-R&L doctrine, nearly always results in imperfect placement because it does not take into account the most important part of subwoofer design - the room into which it will be placed. Now, swap back by putting the subwoofer in the spot where the bass sounded best.