Keeping an in wall sub from shaking?

[HCI]

I have a 10" in wall sub mounted about 1' above the floor. I am having a problem with it shaking the whole wall and giving a distorted sound, kind of like when people have the oversized speakers in a 70 model junker and everything is rattling around. I can lean against the wall to brace it and the distortion goes away. If I vent the wall somehow will this help or make things worse and if this is not the answer what is going to be the best way to go about fixing the issue?

One more thing I did insulate around the speaker when I installed it.

 

[charper1]

You like need to get INTO the wall space and build a sturdy 2x4 frame box for the sub to rest inside of (not attached to any current wall framing or sheetrock) that is also well dampened (sp?) or insulated all around except for the open firing front. This theory may change by knowing what type of sub is in use; maybe changing sub types is an option?. Or simply determining what is rattling and "tightening" things up; glass, wall hangings, etc?.

 

[jayn_j]

I don't know what model sub you are working with, but many of them rely on using the wall to increase low frequency response. You don't want to eliminate that as you will kill the low frequencies.

I would look at several things. It looks like you may be hitting a resonant frequency. This can be solved by adding one or more cross braces to raise the resonant frequency. You could also add a second layer of sheetrock, or change the existing sheetrock for sound board. You might be able to get away with adding a thick padded wall covering. In general though, I think you will need to go into the wall and make structural changes. It might be cheaper to abandon the existing in wall unit and replace it with a conventional sub.

I definitely agree with charper about taking EVERYTHING off the wall and seeing if it goes away. It any be the stuff you hung up there and that can be fixed by mounting it more securely. I had a problem with some movie posters once, that I solved by tightening the mounting wire, getting the mounting hangers into studs and adding some foam tape to the bottom corners.

If all else fails, try isolating the sub from the wall. Does this sub have a rear enclosure, or is it open? If open, try sealing it off and add insulation inside. In any case, mount the sub to the frame with foam isolation. It will kill your bass, but greatly lower the coupling to the wall. One more thing. Is the sub mounted to a wood frame, or just attached to the plasterboard? If the later, you really should build a frame for the enclosure and attach this to the adjoining studs. This will help A LOT and may be all you need to do.

I'm sorry that in my opinion, any solution is probably going to require that you tear apart the wall to some degree.

 

[Paul Wozniak]

You like need to get INTO the wall space and build a sturdy 2x4 frame box for the sub to rest inside of (not attached to any current wall framing or sheetrock) that is also well dampened (sp?) or insulated all around except for the open firing front. This theory may change by knowing what type of sub is in use; maybe changing sub types is an option?. Or simply determining what is rattling and "tightening" things up; glass, wall hangings, etc?.

Do stay away from securing the drive unit directly to sheet rock, I guarantee it will loosen quickly at the screws. From what the original poster says, I would suggest a second layer of sheetrock applied over the old. Glue it and screw it. It sounds like the original sheetrock is resonating with the subwoofer. You might want to look into Sunfire's new subwoofer. Carver has some new ideas about about solving your problem.

 

[HCI]

I am planning on taking the sub out tonight and i will post some pics. I did brace were the wings on the screws tighten. There is no additional bracing in the wall around the sub except for the studs on both sides which should be seen in the photos. there is nothing on that wall except a painting that has no plastic or glass. Just a wooden frame with the canvas wrapped around which is not causing the problem "I have taken it off and same results". I do think it is the sheet rock itself that is causing the problem.

 

[HCI]

Hopefully this fixed the issue. I will let you know in a couple of days as I get time to test the system. I also added a layer of insulation around the edge of the sub between the wall.

 

[Paul Wozniak]

Let us know how things worked out.

 

[HCI]

Well I am going to say that fixed the problem. It has alot more bass now also, probably because its more stable. Today is the first day I have really got to test it and it blew the grill off the front.

 

[charper1]

Nice; enjoy!

 

[jayn_j]

Good show. enjoy.

 

[Paul Wozniak]

Well I am going to say that fixed the problem. It has alot more bass now also, probably because its more stable. Today is the first day I have really got to test it and it blew the grill off the front.

Is your sheetrock still singing along?

 

[HCI]

Is your sheetrock still singing along?

does not seem to be.

 

[Paul Wozniak]

Glad you solved your problem.

 

[jayn_j]

BTW, I'm fairly impressed with your solution. Nice job of figuring out the vibration modes and eliminating them without having to do any cutting. I especially liked the plywood backing you added.

 

[Inno]

I know this is an old thread but I just came across it and noticed your pics. Is that an exterior wall of your house?

 

[HCI]

yes

 

[Inno]

I don't think I would have mounted a subwoofer in an exterior wall for a couple of reasons. First, you've compromised your vapor barrier so now your subwoofer (and home interior) is subject to moisture infiltration from outside. The subwoofer itself will be subject to temperature changes which it's not really designed for. You've also removed a valuable piece of insulation from your home which will of course decrease your heating and cooling systems efficiency. Perhaps you've put insulation around the sub in which case you've eliminated that problem and even improved your bass somewhat. Many speaker manufacturers "stuff" their speaker boxes to improve the sound.
Lastly, because a subwoofer works by moving as much air as possible, any air movement you lose to a surface vibration is lost bass. The more rigid you make the enclosure, the less vibration and the more bass you will get. Sounds like you've taken care of the vibration so that's good. Just thought I'd mention the other facts so you don't run into future moisture/mold problems or possibly even rotten wood.

 

[HCI]

I don't think I would have mounted a subwoofer in an exterior wall for a couple of reasons. First, you've compromised your vapor barrier so now your subwoofer (and home interior) is subject to moisture infiltration from outside. The subwoofer itself will be subject to temperature changes which it's not really designed for. You've also removed a valuable piece of insulation from your home which will of course decrease your heating and cooling systems efficiency. Perhaps you've put insulation around the sub in which case you've eliminated that problem and even improved your bass somewhat. Many speaker manufacturers "stuff" their speaker boxes to improve the sound.
Lastly, because a subwoofer works by moving as much air as possible, any air movement you lose to a surface vibration is lost bass. The more rigid you make the enclosure, the less vibration and the more bass you will get. Sounds like you've taken care of the vibration so that's good. Just thought I'd mention the other facts so you don't run into future moisture/mold problems or possibly even rotten wood.

My vapor barrier is on the other side of the wall. Also the way my living room is designed I only have 3 walls. 2 of them are outside walls and the other is a baby's room which my wife would have shoot me if I put it in that one. My living room is open to my dining room and kitchen which is separated only by a column, then a half wall is separating my kitchen and dining room.

 

[Inno]

I figured there must be a good reason for it. There is a layer of house wrap on the outside of most houses but there is also a vapor barrier between the drywall and the wall studs, I can see it in one of your pictures. It probably won't make that much difference but it's something to keep an eye on. Gotta love the space saving that you get from in wall speakers though!

 

[HCI]

Gotta love the space saving that you get from in wall speakers though!

My wife is anal about having stuff sitting in the floor. Its the only way she would let me put the system in. I am actually surprised at how well the speakers blended into the wall and ceiling. After I painted it all you cannot really tell there is anything there unless you are looking for it.