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subwofer vibrating through house

By Norehca ·
i currently have a 4.1 surround sound system by creative. Its a simple but powerful 40-watt system. The subwoofer is wooden, and even on its lowest setting on both the subwoofer istelf and in the volume control it still vibrates all through the house. even more wierd is its sitting on concrete in the basement where my room is. i wouldnt think concrete would absorb the vibration and send it through the walls. i keep it about 6 inches from the wall, any farther away and my foot keeps hitting it.

my main problem is that i cant put my sub-woofer at a decent bass level without it tearing the house down. does anyone know of any solutions of how to fix this? maybe a placing it somewhere else?

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by HAL 9000 Moderator In reply to subwofer vibrating throug ...

That can not happen if everything is working correctly and yes you are right Concrete will not allow that to happen.

The most likely problem here is that you have a very low Frequency Hum occurring which is below your hearing range but still enough to create vibrations that will cause the problem. You need to make sure that you have a solid earth between all the equipment and that may require running an earth lead from the main Sub wolfer enclosure to the computer case.

I would also check the sound output of the computer before starting to mess around as it's very possible that is causing the problem and the Sound Card is producing the Low Frequency Hum. Sitting the Sub wolfer on a absorbent material will minimise the problem but if the sound waves are strong enough they will still cause the walls to vibrate.

Col

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Concrete and Bass

by TheChas In reply to subwofer vibrating throug ...

Concrete will neither absorb or dampen the bass from the sub-woofer. It does work as a very good reflector though.

The answer lies in the basement walls and ceiling. Most likely, the interior basement walls are being vibrated by the base and transmitting the base to the floor above.

Short of tearing the walls down and rebuilding them, your best option would be to hang heavy drapes or tapestry on the interior walls.

Depending on how the ceiling is built, it can also transmit sound waves to the floor above.

The location of heating and air conditioning ducts can also play a role in sound transmission.

In order to sonically isolate a basement room from the rest of the building, you need to build the walls so that they are not rigidly tied to the upper floors.

Chas

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other solution

by Norehca In reply to Concrete and Bass

Well id rather find an alternate solution than messing with the walls. If you dont mind, what are some materials that i could use to sit the subwoofer on that will absorb the sound? Right now i have it sitting on a box that my mobo came in with a flannel blanket folded inside of it. Doesnt seem to be working too well. It sounds like it minimized it a little, but not enough to keep my mom screaming from upstairs to turn it down. Although she doesnt get that its not the volume thats creating the vibration. t does it even when the volume is is quite low.

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Unfinished Basement

by TheChas In reply to other solution

If it is an unfinished basement, especially if you have forced air heating, the sound is traveling through the floor and ductwork.

Setting the sub-woofer on a box is most likely isolating and absorbing energy from the port.

In order to absorb energy from the sub-woofer, place it on heavy rubber floor matting.

In an unfinished basement, your best option is to install a suspended ceiling using acoustical grade ceiling tiles.

If the basement is finished start rapping your knuckles on flat surfaces to identify what wall or ceiling section vibrates.

Start by looking for duct work that is not insulated. That is still the most plausible transmission route. Covering the duct work with a material referred to as "Duct Board" with an air gap between the duct and the board should do the job. You can then cover the duct board with just about any wall covering. Also look for loose pipes such as electrical conduit. Water pipes should not vibrate. Drain pipes might.

Next, look at how the ceiling is installed. If the ceiling is installed directly to the floor joists, you should get some relief by blowing fiberglass insulation between the joists. 2" - 3" should be enough.

For paneled walls, your best option is heavy fabric coverings. From heavy upholstery fabric up to rugs.

If things are really bad, anechoic foam may be your only option. The stuff is not cheap, but can absorb nearly any noise.

Chas

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walls

by daveodesign In reply to Concrete and Bass

basement walls are 12" thick concrete. if they were to vibrate they would crack. they dont vibrate.

there is no ceiling. its an unfinished basement. the floor above is the ceiling.

the upstairs walls sit on the wooden floor, which sits on the concrete. they are nailed together at best. the house is held down mostly by its own weight.

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Wow!

by NickNielsen In reply to subwofer vibrating throug ...

The reason the sound is propogating throughout the house is that some part of the structure in the basement is resonant in that frequency range. That is, some frequency in the subwoofer's range is causing sympathetic vibrations in the structure. (See http://tinyurl.com/q8qw3 for more on resonance.)

TheChas has already covered what you will need to do to alleviate this. I don't think you will be able to fix it without rebuilding.

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simple

by daveodesign In reply to subwofer vibrating throug ...

concrete is a hard reflective surface. when you put the sub in a corner, it gets louder. the sound is being reflected out right into the absorbant wood above you. the subwoofer box is a certain size and hollow in order to make it as loud as it is. im assuming theres a hole on it somewhere - stuff some old tshirts, or preferably foam, into the enclosure, but be sure it dosent touch the speaker cone. this will dampen the sound.

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