The audio side of a home theater setup can be intimidating. There are audio receivers to figure out, speaker placement, and you may even be considering acoustic panels for the walls or ceiling. It’s easy to forget one of the biggest surfaces and the effects it has on the soundscape: the floor. And since, more often than not, the subwoofer is the only speaker that physically sits on the floor, the next question is what effect that surface--whether it’s carpet or hard flooring--might have on the subwoofer’s sound quality.
Although many people have had this question, there is no perfect answer. While a bare hard flooring can allow the deeper subwoofer sound waves to travel further without being dampened, a carpet can help to balance the sounds in the room together better, depending on where other speakers are placed.
Since every home theater room is different, and every theater setup (where the speakers are, whether it’s 2.1, 5.1, or 7.1 channel sound, etc.) varies, there’s not a one-size-fits-all answer here. You’ll have to pick a solution that’s right for your unique setup, and you may need to try several to see what sounds the best. But before you make a call, here are some things to think about.
If your home theater room is carpeted, you’ll probably have an easier go of figuring out the speaker system that you otherwise might in a hard floor room. The subwoofer can sit right on the carpet, and the sound should be propagated from the subwoofer and mixed with the rest of the soundscape just fine.
One of the pros of having a carpeted setup is that the subwoofer manufacturer is basically expecting this. Because of that, the way the speaker is designed will be such that being on carpet compliments it. The subwoofer will vibrate a lot when it’s producing sound, and being on carpet will allow some of these vibrations to be absorbed, keeping the speaker box stable, and the speakers themselves projecting the right sounds in the right direction.
And even for a down-facing subwoofer, the amount of sound being absorbed by the carpet is likely going to be negligible. Since the subwoofer is there to push deeper sounds and longer wavelengths, the sound waves it’s producing simply won’t be affected as much as shorter wavelength sounds like those produced at the rest of the speakers in the system.
Starting out with hard flooring, or any kind of hardwood flooring is going to give you more options than if you already have carpet because you can always add rugs or audio-absorbing material to simulate carpet if you need to. There are simple absorbent pads like the RightChoice XL-Pro Subwoofer Isolation Platform, but there are also more advanced units that have springs and vibration canceling designs like the Auralex Acoustics SubDude-II. You have the benefit of testing it out both ways and seeing which sounds better.
Although the hard flooring is going to be a better medium for allowing the deeper subwoofer tones to resonate through, it can cause complications too. Since the hard floor is a flat surface, it will reflect sounds just like the walls will. Read our article on acoustic panels, you'll learn how sound reflects off of large flat surfaces. These bouncing sound waves need to be managed to a certain degree.
Although the sub shouldn’t have any problems with hard flooring or hardwood flooring in general, depending on the set up in the room, the other speakers, etc., it’s possible that there is just too much reflection in all directions, which can cause the subwoofer’s channel to overpower the rest, or to be under-powered and lost. You could experience resonance because the hard flooring is better at carrying the deeper sound waves. An example of resonance is the vibration and rumbling in adjacent rooms due to the excessive bouncing of sound waves.
With all this confusion about the subwoofer and floor material, you may be wondering if you can skip the floor entirely. The answer to that is yes, but it’s probably not going to affect the quality that much. The way hardwood and carpet effect the sound, you’re not going to gain much by mounting the speaker on the wall, and so you should probably avoid this unless it’s specifically so that you can reduce vibrations in adjacent rooms.
And what about placement in the room? The default position most subwoofers end up in is at the front of the room, near the entertainment system. This is probably for a few reasons, chiefly because it’s easiest to wire there, but you should know that the nature of the sound coming from a sub mean that it really shouldn’t matter where you place it. If you have a wireless system, or don’t mind trailing the wires around to test the sound, you may consider putting the subwoofer in the corner, or even behind the couch, to see where it sounds best to you.
The solution to getting the subwoofer in the right spot, and getting the best sound from it, is to try it out in a few different ways to see what sounds best to you. If you’ve got carpet, put the subwoofer where you think it might sound best, then listen to it and move it around to other spots, like on its side if you feel so inclined (our guide). If you’re on hardwood, do the same thing but try with and without a subwoofer dampening pad like the Auralex Acoustics SubDude-II.
With a little variation, it should be clear what’s going to sound the best, and this experimentation will help you get the most out of your audio setup. There’s no right answer when it comes to subwoofers and carpet vs hard floor because it’s really not just the carpet or hard floor that you’re optimizing for. As with all the components of a good custom home theater, you’re optimizing for the uniqueness of the room itself.