low frequency tube traps

Enclosures and acoustic damping to help quiet them.

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Nevarion
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low frequency tube traps

Post by Nevarion » Mon Feb 28, 2005 10:04 am

An idea, I wonder if it is possible to reduce the low frequency noise like they do in hifi by using tubes made of something like fiberglass.

http://www.teresaudio.com/haven/traps/traps.html

Ofcourse you have to make them smaller so they fit in the case but if it works that would be great, couse It's hard to do anything about the low frequency noise.

JanW
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Post by JanW » Mon Feb 28, 2005 11:08 am

:shock: :shock: Image
I can understand that this would be useful for HiFi freaks, but to silence a computer? Looks to me that attacking noise at the origin would be waaaay easier.

Oh, you want to put it inside the case? But surely the modes of the case will be at a much higher frequency than those of a room? It looks like these traps are most efficient around 400Hz, but scaled down to the width of an ordinary computer, that might mean it's efficient only around 4000Hz. Plus, these need to be at specific positions wrt the noise source and the listener:
Image
So maybe of help for people who stick their had in the box often? :D

Sorry, didn't mean to make fun of your idea. But at first glance (and I don't know anything about the matter) it looks like physics is against this being useful.

Green Shoes
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Post by Green Shoes » Mon Feb 28, 2005 11:13 am

ditto Jan. Sound dampening is useful in theory, and should work at least somewhat with high frequencies, but those low-frequency waveforms are just too darn big for anything you could fit inside your harddrive to soak up. That's why some of us in apartments are at war with our upward neighbors who own downward-firing subwoofers in their home theater. :evil:

Nevarion
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Post by Nevarion » Mon Feb 28, 2005 12:18 pm

posted just becouse i cant get rid of the low frequencys from the hdd in my case (it is a spinpoint 160GB) i have it very good suspended and the case is stuffed with aucustic absorbs. the hdd still makes some humming noise and I dont like it....

AndyP
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Post by AndyP » Mon Feb 28, 2005 1:34 pm

A 2.5 notebook drive is a solution. Slightly expensive and not the greatest performance, but incredibly quiet.

JanW
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Post by JanW » Mon Feb 28, 2005 1:38 pm

The tube traps take advantage of the fact that in corners of a room the energy of the low frequency sound waves is completely stored as air pressure. Because of their construction, tube traps absorb the pressure variations at those points. I believe it would be very difficult to efficiently dampen pressure variations in the small space available in a computer case corner.

BUT you could try the opposite: for the lowest frequency mode, all the energy is stored as air movement in the center of the case. So if you can come up with a way of putting a sound barrier in the center of the case without affecting airflow, that could help. I'm thinking of a sheet of acoustic foam, ideally with a barrier mass in the center, hanging parallel to the case door in the center in front of the M/B. Depending on the location of the HD, you might want to play with the orientation of that foam.

Just my EUR0.02

Nevarion
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Post by Nevarion » Mon Feb 28, 2005 2:31 pm

I'll do that! thanks for all info :D. Just what i was expecting from a forum of this quality :wink:

JanW
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Post by JanW » Tue Mar 01, 2005 12:28 am

I'd be very interested to hear how this worked out! Remember that I'm purely speculating here...
On second thought, depending on the frequency modes of the case (and the harddrive), you might also want to play with the position of that barrier (at the center, at 1/3, 1/5, 1/6 of the case size...) to find out where it dampens most effectively the offending frequency. And contrary to what I said before, it seems to me now that the barrier mass is more important than the foam. You can use roofers tape or something like that. That has the advantage that it can be fairly thin.

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