low freq vibration reduction ...

**fibreKid** · **06-30-09, 12:29 AM**

Hello;
Before I start patching up the walls and ceiling I figured I would run this by the group.
I have a TV room that is as close as I'm going to get to a dedicated HT. The TV is in an entertainment center and the couch is about 12 feet awayon the opposite end of the room. The room is about 16 feet in length and I'm in the process of running surround and SUB wires (shielded coax) from the front to the back of the room via up the wall behind the ET and across the ceiling and split them at the back of the room over the couch to their respective corners. The TV room ceiling is the floor of the master bedroom so I don't have access from the attic crawlspace. The run across the ceiling front to back isn't obstructed (luckily) but I started to think about vibration from the sub. I've already had to put felt sticky pads on all the pictures in the room to reduce the vibration noise. The sub is solid to 18hz, pretty good to 16 but drops like stone at 15. I've picked up some 1/2 inch pipe insulation that you would use outdoors help prevent freezing. It's fairly soft and I'm thinking that it will reduce the chance that the cable will vibrate in the ceiling. I figured I would snake the speaker wire through them, left/right in one and the shielded coax in the other.

Does this seem reasonable? Anyone else have better ideas?

Thanks much
-john

**Space** · **07-02-09, 08:06 PM**

If the low frequency is that much of an issue, why is a decoupled ceiling not being considered for this room?

Moving or shaking wires seems to me, are the lest of the concern with the transmission thru the ceiling into the floor above.

To be honest, I don't know if you will even hear this movement of wire with a bass that makes that much vibration.

Where is your build thread, if I may ask?

Brien

**fibreKid** · **07-02-09, 11:45 PM**

Hello;
There is no build thread. I am just now getting around to putting the surround speakers where they should be. My wife and I decided that we wanted recessed lighting in the room and we purchased the lights about 2 years ago. I purchased the tools and faceplates about 13 months ago. It's been a project on the back burner for a very long time. The only reason I even thought about the vibration issue was I remembered how loud and annoying the pictures on the walls were when I played some tracks from a low frequency test CD that came with the sub. I'm figuring that the walls and ceiling are going to vibrate about the same. The difference is a picture is hanging vertical leaning against the surface and the wires are laying on it. It might not even be an issue but tearing into the walls again isn't an option. This has been a painful process.
All I'll say is ... Imagine you are doing this solo and you have a 56" 9/16 fish bit (flexible drill bit) that you are trying to work with in between 2 x 12's on 12 inch centers. The drill guide is in your left hand and the drill is in your right and the wood is 20 years old. An angle that is slightly off gets ugly.
-john

**Ted White** · **07-07-09, 01:02 PM**

In these environments it's always a good idea to muffle anything that's loose. Everything will vibrate at some point and could audibly rattle.

Ceiling cans are notorious for buzzing. Pre-tape them up with electrical tape and tap them to see what rattles

**Space** · **07-07-09, 08:26 PM**

Indeed, and the low voltage cans should be placed inside boxes to prevent the sub noises from going up into the overhead rooms.

Although, I admit, I cannot visualize this overhead ceiling configuration that is being discussed.

**fibreKid** · **07-09-09, 02:04 AM**

Ah nuts, I didn't even think of the cans rattling. They are in the ceiling but if I have to I can drop them down and tape them up. They are halo 6" diameter and about 8 or 9" tall. I've tapped them and they seem pretty solid but the covers that slide in to hold the bulbs may cause me some troubles. I guess I just have to test them out. I didn't think about the noise through the floor but, it's my bedroom and I won't have it very loud if my wifes asleep and if I'm not upstairs I guess I won't care

**Ted White** · **07-09-09, 10:29 AM**

That's a large diameter can. Lets plenty of sound through. You might consider a backer box.

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