A down firing subwoofer means that instead of a side fire or front fire, the sub emits the sound directly onto the floor surface. Down firing subwoofers are popularly used with surround-sound systems to increase the vibrations and rumbles heard and felt during film viewing. In fact, down firing subs are essential to get the maximum audio quality from your sound system.
Positioning Down Firing Subwoofers
Most down firing subwoofers are placed on softer surfaces such as carpet. 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. And since the low frequencies that subwoofers emit exclusively are omni-directional, it is unnecessary to point them directly at a hard, reflective surface.
If the sub is placed on a hard surface, it would be a wise move to place small rubber feet on each corner to eliminate movement from vibrations and to place a small piece of carpet or other soft surface directly underneath it to absorb some of the sound. This will ensure you don't bother your neighbors with the rumble of movie explosions from your home theater.
Types of Down Firing Subwoofers
There are specific types of subs designed for down firing; however, a normal subwoofer can be down fired simply by placing the face (the subwoofer's hole) down on the floor. The actual difference between subs specifically designed for down firing and normal front or side firing subs is not always minimal, but can be, depending on the quality of sub.
The subs specifically designed to down fire are a more accurate representation of low-end frequencies because the floor absorbs most of the direct sound pressure and sends it outward, but most residential consumers will not be able to hear the difference.
Do You Need a Down Firing Subwoofer?
It is important to assess the effectiveness of the subwoofer that already exists prior to placing it in the down fire position or purchasing a new one. Ask yourself these questions: Are you getting enough low-end sound when you watch movies and listen to albums? Is the sub in the corner of the room, and if it is, are you getting as much rumble as you want? Do you want more vibration from your sub throughout the area? If you answered yes, down firing your pre-existing sub, or purchasing and installing a sub that is specially designed to down fire will achieve that.
Another crucial component to the purchase of a new down firing subwoofer is to make sure the specs on the model you wish to purchase will work adequately with your existing amplifier. You do not want to under- or over-power your sub. While you may get away with over-powering, under-powering is never a good idea. Consult with a home theater expert on this issue, and you should be fine.