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 Post subject: Question: Damperners, Vibration insulators
PostPosted: Fri Sep 05, 2008 12:41 am 
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Joined: Fri Sep 05, 2008 12:24 am
Posts: 4
Location: Singapore
Is this correct?

JoeWPgh wrote:
Let me follow this up as I understand it:
There are 3 separate things often referred to as 'dampening'

There is the actual dampening of the case panels to deaden their vibrations. You do this if your case panels are audibly vibrating.

There is mass loading to increase the amount of mass the sound energy must penetrate. You do this to try and keep noise inside the box.

There is diffusion to break up the moving air of a sound wave. You do this to soften how sound waves hit the case panels.

For dampening, I like butyl. You need not cover every inch of a case panel to deaden it - just a few strips here and there - much like a drummer might use a strip of tape or 2 to control the vibration of his drum head. Of course if you cover the entire case panel with it, you've also mass loaded the panel, so you're 2 for 2.

For mass loading, self stick vinyl floor tiles are effective and cheap. I don't think they are quite the equal of butyl for dampening, but they take you a good way down that path as well.

For diffusion, I agree again. Open celled foam is the easiest solution. I usually save the 'egg-crate' bumpy stuff that some computer parts ship with for just such use.

Of course, you could gild the lily and apply all 3, and only add 15 lbs or so to your box :)

By far the easiest thing to do is to start with quiet components. This will usually negate the need for most case dampening.

Luminair wrote:
this is simplified possibly to the point of being inaccurate, but:

sorbothane for vibration isolation and probably vibration dampening

vinyl for vibration dampening via mass-loading and sound wave reflection

dense open cell foam for sound wave absorption



What does this do? Where do you put it?

http://www.silentpcreview.com/article71-page1.html

Do these work well? http://www.earsc.com/fantechniques.asp

Thinking of buying these: What do you think?

http://www.petrastechshop.com/12vavidakit.html or http://www.petrastechshop.com/12sovida.html

http://www.petrastechshop.com/pegviabbl.html for pump

http://www.petrastechshop.com/fanviissof4.html or http://www.sidewindercomputers.com/setof4rufanr.html for "fan screw"(dampener or vibration insulator?)

Another question, what screw size does s-flex "F" use? This will help me in choosing either "fan screws"

Sorry if this has been posted before. Did some checking but no concrete answer. Also, hello to all! :D


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 Post subject:
PostPosted: Fri Sep 05, 2008 9:46 am 
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Location: Grand Rapids, MI
Mostly correct. The first two are the same thing.

Acoustipack is meant as a multi-approach damping material that combines the mass-loading effect of butyl rubber with some open foam for diffusion.

Ears work well and will be much better at vibration isolation than the gaskets. The only difference between the two you show, I think, is that one goes through both mounting holes of the fan and the other only goes through one (the length is different). I could be wrong though.

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 Post subject:
PostPosted: Fri Sep 05, 2008 3:45 pm 
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Joined: Fri Sep 05, 2008 12:24 am
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Location: Singapore
Thank you very much for your reply!

What I still don't get is this:

Quote:
There is mass loading to increase the amount of mass the sound energy must penetrate. You do this to try and keep noise inside the box.

There is diffusion to break up the moving air of a sound wave. You do this to soften how sound waves hit the case panels.


Could you rephrase that please :lol:

From what I understand, acousticpack is big and you put in beneath your case to prevent vibration from reaching the desktop. Alternatively, use it for the pump, like this one: http://www.petrastechshop.com/pegviabbl.html

Could I use both of Ear's screw with gasket? Is the ear brand the best for these "screws"? There is also a nexus's one here: http://www.petrastechshop.com/fanviissof4.html


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 Post subject:
PostPosted: Sun Sep 07, 2008 5:02 pm 
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Location: Grand Rapids, MI
Yeah, I had issue with that comment when it was made.

Basically, there are 3 ways of reducing noise: mass-loading, isolation/decoupling, and diffusion. Mass-loading and isolation work best on mechanical vibrations and work by absorbing them and preventing them from transferring to other areas of the case. Suspending a hard drive is one way of achieving this. Mass-loading a case panel will achieve this effect as a greater mass requires more energy to vibrate than a lesser mass. Therefore, with a given amount of "vibrational energy" a heavier object will vibrate less and it's vibrations will be lower in frequency (which tends to make it harder to hear).

Diffusion works only on very high-frequency sounds, by dispersing the reflection of a sound into many directions instead of just one. Think of shining a laser at a mirror, the mirror reflect the laser in a coherent beam. Now use a piece of roughened metal, it will spread the reflection out to the point that the beam is no longer together. Same thing with sound. The reflections of sound will not reach the observer as strong as they were.

Acoustipack does both mass-loading and diffusion. But using the ears and gasket most likely wouldn't work, nor would it be necessary. They all work the same however, you just want the softest (lowest durometer) you can get.

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 Post subject:
PostPosted: Mon Sep 08, 2008 12:02 am 
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Joined: Fri Sep 05, 2008 12:24 am
Posts: 4
Location: Singapore
Ah! I get it now. That's so much clearer than the previous post

I believe the pump and fan will vibrate and I don't wish my radiator to vibrate as well, since it would amplify the sound. Am I right to say that? Therefore I think the gel-stuff would help dampen the noise by a small amount.

As for mass loading and diffusion, I doubt I would be able to use that technique to reduce noise furthur since my hdd is near silent and hardly vibrates.

Thanks


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 Post subject:
PostPosted: Fri Dec 18, 2009 10:22 pm 
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Location: Egypt
I use acousticpack which is big as mass loading for my operation.

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 Post subject:
PostPosted: Wed Jul 14, 2010 7:09 pm 
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Joined: Fri Apr 23, 2010 9:01 pm
Posts: 95
Location: Southern France
I wanna know if someone here tried the foam designed by Cooltek.

It's a german brand/ site it seems and the thickness of their foam seems interesting to me: 14mm (compared to 4/6 mm for "crap mate")

See here

The design also seems more "appealing", not your typical "crap mate" if you ask me such as Akasa paxmate which i'm familiar with.

Anyway, i'd love to know if someone here tried it before i empty my wallet

Image


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