2. misc-audio
  3. 140089-1783

Stopping Vibration from Walmart trucks

I have for the past two weeks had problems with my living room and master bedroom having a low frequency issues in the center of each room, when certain trucks are delivering at a Walmart about 100 yards or so away.
Does anyone know how to disperse the low frequency waves in the room. As you move towards the walls, even in the direction of the Walmart the subwoofer effect goes away.

I have probably contributed to the issue by taking down an old wooden fence and replacing with a wrought iron fence, so we could enjoy a greenbelt between us and Walmart. My wife and I noticed the problem about two days after replacing the fence. It is only noticeable on some evenings with certain trucks, and is actually louder in my living room than at Walmart.

I was wanting to add bass traps are whatever is needed, as I don't want to go back to the fenced in backyard.

Thanks,



acman3
geoffkait's avatar
geoffkait
23,365 posts
 
If memory serves Linn’s suspension doesn’t go low enough. That’s why they’re always trying to update their suspension, the Trampoline or whatever. In order to defeat the Walmart truck you have to go down to 2 Hz.
folkfreak's avatar
folkfreak
1,349 posts
 
Geoff -- as far as I am aware no turntable suspension (barring ones such as the Dohmann Helix with an integrated minus-K isolation system) has a suspension that deals with vibration outside the audio range. Agreed the Linn is exceptionally floppy (i.e. high resonant frequency) but most are like that - my EAR has among the stiffest springs I know but again is no use against the sub 10Hz issues we are talking about here
folkfreak's avatar
folkfreak
1,349 posts
 
It does seem however that the OP has a secondary issue in so far as the room itself is exacerbating the sub-sonic issues. Bass traps will not help as they are also tuned to the audio range and cannot deal with sub 10Hz (think how large such a bass trap would need to be)

I wonder if the issue is the floor acting as a resonator then mass loading the floor in the appropriate manner might break things up?

Failing that as others have suggested an isolation fence could be a good idea -- many suppliers make such a thing but again it will not deal with the sub-sonic problems ...
geoffkait's avatar
geoffkait
23,365 posts
 
If a suspension is exceptionally floppy it means the resonance frequency is low, not high. If the suspension is very stiff it means the Fr is relatively high. Resonant frequency is proportional to the square root of spring rate (all springs total). Almost all isolations systems extant deal with vibration with frequencies outside the audio range, I.e., seismic vibration, in range 0-20 Hz. Like that produced by Walmart trucks.
acman3 OP
4,117 posts
 
Folkfreak and all, the big problem is the room resonating. It is not a problem caused by speakers, although I am sure it affects both speakers and turntable.

I was hoping I would be able to do something inside the room like Bass Traps. I will look into the issue via the internet, but like all, I was hoping for a magic bullet, I had not thought of. I guess I have to put the fence back up or live with it.



 
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