Last night I helped my friend hook up her new surround-sound system. After it was all hooked up and I cranked the 311, I noticed that the subwoofer, which has the speaker and tube pointed downwards, probably makes enough noise to bother the neighbor downstairs.
The floor is wood, I’m assuming with a concrete base. Is there a way to keep too much of the bass from transferring through the floor, without muffling the sound for us? Some sort of pad, or even just a piece of carpet?
I had mine on a piece of dense foam. The girl downstairs never complained (and I did ask.) Granted I also didn’t turn my music up very loud, so that helped. The tube was also not pointed downward. If you know whoever lives downstairs, it might not hurt to try something out and ask if it’s too loud.
Bass is not stopped by things like carpet. To stop bass, you need a dense material like drywall or lead sheeting.
Another source of noise is impact noise - noise that’s transmitted directly from the feet of the subwoofer to the floor. To stop that, you can put the feet on rubber or thick felt pads or something. But to stop low frequency sound waves, carpet and foam are completely useless.
I’d say start by getting some thick felt pads for the subwoofer feet. That’s probably all you’re going to be able to do, short of building a second floor on top of the current one.
I think the easiest, low-tech solution is to visit the downstairs neighbor and determine if there is a problem in the first place. On a quiet evening (the kind of night that neighbors are most likely to notice the noise) do a site survey; call the neighbor up and increment the volume up until he/she can hear it (or is bothered by it). Mark that spot on the stereo dial with pencil or crayon. As long as you don’t exceed that volume, you should be fine. Make sure that you and the neighbor exchange phone numbers, so if this plan fails he/she can call you and not the police.
The sub-woofer can go anywhere in the room. I think you could reduce the annoyance to neighbors by suspending the sub-woofer from the ceiling. That way you won’t have the floor transmitting the sound so readily. The experience for people in the room should be unchanged, or perhaps even enhanced.
Suspend it so that the speaker points toward the seating area. A level check is still a great idea, but this may allow you to get a few more notches on the dial.