Dampening Materials?

Enclosures and acoustic damping to help quiet them.

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saipoob
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Dampening Materials?

Post by saipoob » Sat Dec 22, 2007 6:47 pm

So I did a little homework on dampening materials:

Damptek is made primarily with EVA foam.
Dynamat/eDeadv1 are butyl rubber.
eDead Teklite is closed cell neoprene (weird...)
Acoustipack is a polyurethane mixed cell.

I was thinking that what I'd do is buy sheets of these materials from McMaster and make a 4 way laminate of the following materials:

1/8" EVA foam
1/4" butyl rubber
1/4" polyurethane
1" textured melamine

I was hoping to solicit opinions:

Is this way overkill?
Is it worth the effort of making the composite? I was thinking the different layers would block different frequencies.
Are any of the above materials better/worse for dampening and should be skipped?

I've read the dampening material posts and it seems like people either just use Damptek/Acousticpack, Dynamat/Teklite, or butyl rubber/melamine. I'm a little Type A if you couldn't tell ;)

jessekopelman
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Post by jessekopelman » Sun Dec 23, 2007 3:13 am

What is the problem you hope to solve with damping materials? The big issue with damping materials is they are only good for blocking higher frequency sounds. The reason being that the the lower the frequency the sound the longer the wavelength and thus the thicker the material must be to have any hope of seriously attenuating it. If you've already got all your fans nice and quiet, the biggest noise-maker is going to be your HDD. Now the damping material may subdue the seek noises, but it will do nothing for the steady hum of a powered up HDD. The reason why is that a 7200 RPM drive spinning produces a 120 Hz tone and the wavelength of 120 Hz sound is about 3 meters -- you'd need over a foot of damping material to do much at that frequency. What's worse, the material would have to completely surround the drive/case as such the distance between the front and the back of the case is so small relative to wavelength that it would do no good just to block the side facing you. Really, the only thing damping materials are good for, that isn't better solved by replacing fans, is solving problems due to the case itself vibrating or reverberating. If that's the problem, 1/8" of butyl plus 1/4" of foam will do the trick.

Lou_H
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Post by Lou_H » Sun Dec 23, 2007 11:15 am

These materials are usually all referred to as “dampeningâ€
Last edited by Lou_H on Fri Dec 28, 2007 12:28 am, edited 3 times in total.

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Post by pingu666 » Mon Dec 24, 2007 7:10 pm

ive looked into it a little bit, as people have said "you can get much better and cheaper than aqusti pack"...

you either need to buy huge quantities, or postage costs, or labour costs (your own) for trimming/assembing the stuff, plus organisational hassle :(
cost is a big issue for me as im unemployed :(

also what are you going to bond your custom stuff together with?

these guys seem cheap

hmm
(same size as a accousti piece from the duluxe pack, but 20mm depth, and about half the density (60-65Kg/m³ accoust)

they offer spray adhesive too
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saipoob
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Post by saipoob » Mon Dec 24, 2007 10:04 pm

Wow, this is a great help! Thanks everyone.

My concern is that with the computer I'm thinking of building that despite the fact that I will be building with all quiet components the additive noise of the fans would be great. I was hoping with some dampening materials on the case that it would reduce some of that, as well as hopefully a slight reduction of the "whoosh" you get my moving a large amount of air.

Lou, thank you so much for those numbers and your advice. I think that's the best, most definitive example of the difference. I am definitely a do it yourself type but it seems like from your experience given that I'd only be doing one computer that I'm not really saving myself all that much by doing it myself.

Although I found you can get melamine 1" thick for $36 for a 2'x4' piece with a coating that I think would make it easy to add adhesive - 9162T349. Not really sure how that'd work out in a PC.

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Post by gb115b » Tue Dec 25, 2007 3:51 am

i just don't think this will affect the fan noise 'whoosh' particularly...

for that i'd just build a baffle at the back (with your dampening materials?)

i think the acoustipack is expensive, but worth it if you're keen on getting those last few dbs down from your optical / hdd drives

but then i live in the uk...so shipping costs aren't too bad here...

i was also suprised at the difference the big blocks of foam (used for filling up empty drive bays) made to the overall sound of the system...

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What case?

Post by GuyClinch » Wed Dec 26, 2007 2:29 pm

I have P160 and it had alot of vibration issues (as it's aluminum) but I used Dynamat extreme and it solved the vibration issues with the side panels.

So it's pretty useful. It's now quieter then my Sonata case (which granted isn't though of as all that quiet.)

For my next build I am thinking about using a noisy case like a TJ09 but with fairly quiet drives, an aftermarket video card cooler (like the thermalright one) and a thermalright 120 extreme CPU cooler.

I wonder if adding a foam on top off the dynamat will help..either that or I will just suck it up and buy a P182. Fugly case though - its okay with the door closes but all that plastic when you open up the front door - bleck. My g/f will go ballastic.

Pete

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Post by colin2 » Wed Dec 26, 2007 4:56 pm

The Jessekopelman and Lou_H replies are great and should be turned into a sticky, as this areas is rife with misconception.

Just to pile on, damping is worth doing if you have things in the case that are gonna vibrate no matter what, and you don't want their vibration setting other things rattling. But it doesn't sound like that's your problem.

As far as the whoosh goes, aside from getting quiet fans and cutting out fan grilles, I doubt there's much you can do (what case are you using?). The real returns are to using cooler components that can get by with gentler airflow.

I also don't think of whoosh as very high-frequency (and hence likely to be abated by foam or melamine), but maybe someone else will straighten me out on that.

Open-cell foam's cheap (sometimes free as packing material) and there would be no harm experimenting with it. It may also shape the airflow inside your case in helpful ways. Air inside the case can behave in odd resonant ways (Mike C has written about this from time to time). I wonder whether the foam blocks gb115b writes about are reducing the eddies and so forth.

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Post by pingu666 » Wed Dec 26, 2007 11:15 pm

ive used foam from packaging. its ok, its free, so stuff it in :). Ive got a suspision accousti pack covers all the bases well, and isnt too bad value for money
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Post by gb115b » Thu Dec 27, 2007 5:13 am

colin2 wrote:Air inside the case can behave in odd resonant ways (Mike C has written about this from time to time). I wonder whether the foam blocks gb115b writes about are reducing the eddies and so forth.
in my own experience, the sound blocks do change the character of the noise coming out...

it could be reducing cavity resonance (reducing standing waves) but i don't really know enough about it...all i know is thats its quieter with the blocks than without!

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Post by pingu666 » Thu Dec 27, 2007 10:58 pm

if the fan noise is escaping from rear/side hole, you could build a tube, sound proofed with a "air chicane" in and stick that on the hole in question :)
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Post by The Gangrel » Sat Jan 05, 2008 12:58 pm

AFAIK, anytime there is sound produced in an enclosed space there will be frequencies at which the enclosure will resonant/vibrate in sympathy, enforcing said frequency and harmonics.(Hum in the shower raising and lowering the frequency and you'll soon hear this for yourself).

You can soft mount things and so on, but the fan is still producing some sound(it's moving air after all), which may excite the case in such a way that you can hear it resonating. Foam should, at higher frequencies, stop the enclosure getting excited therefore dulling the resonance.

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Post by Luminair » Sun Jan 06, 2008 1:45 pm

I've been thinking of buying some sorbothane hemispheres to attach to the sides of things that vibrate: http://stores.ebay.ca/dang-good-stuff_S ... idZ2QQtZkm

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Post by Lou_H » Sun Jan 13, 2008 10:46 pm

I've been thinking of buying some sorbothane hemispheres to attach to the sides of things that vibrate: http://stores.ebay.ca/dang-good-stuff_S ... idZ2QQtZkm
I have been buisy on other projects so I'm a little late with this reply.

Their price looks way high. They want $25.48 for a 4"x4"x 1/2 of sorbathane and McMaster sells it for for $7.95 #8514K115 (McMaster calls it Ultra-Soft Polyurethane now) The Sorbathane from McMaster Carr that I used has a softness durometer rating of 40. It's very soft for HDD vibrations and is sticky almost like gum. I don’t see a durometer rating for the products on that ebay page.

Seems that hanging the hard drive with elastic straps is more popular now.

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Post by Luminair » Mon Jan 14, 2008 2:34 am

re: high prices

Yeah unfortunately Mcmaster-carr doesn't ship to Canada, so we take what we can get :\

redtop
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A question about my case...

Post by redtop » Thu Jan 31, 2008 8:55 am

I've got three PC's in Antec 2600BQE cases. I run cool and quiet (not silent) except for some case vibration. It's mostly a low frequency "hum", but I would like to see what I can do to diminish or eliminate it. The Western Digital SE16 hard drives are mounted on the standard Antec grommet mounts in the cages. If I place my hand against the "door" side the hum is reduced...if I press slightly the "hum" disappears.

I'm not looking to put a full $80/computer into an AcousticPak Deluxe type of system. Just get rid of the "hum". The cheaper the better as long as it is effective...

Which of the above products would you recommend?

Thanks in advance... :D
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Re: A question about my case...

Post by MikeC » Thu Jan 31, 2008 9:29 am

redtop wrote:I've got three PC's in Antec 2600BQE cases..... I'm not looking to put a full $80/computer into an AcousticPak Deluxe type of system. Just get rid of the "hum". The cheaper the better as long as it is effective...

Which of the above products would you recommend?

Thanks in advance... :D
None. You can solve this by suspending the HDDs in elastic string. See the stickies in the storage forum, and my original article here.
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Post by seraphyn » Thu Jan 31, 2008 10:43 am

If you don't have the room for suspension, you might want to put the HDD on top of a layer of foam.

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Post by jhhoffma » Thu Jan 31, 2008 11:17 am

Then buy some heavy self-adhesive vinyl floor tiles and put them on the inside of the case panels. Or you can use "roofer's tape" also called Peel&Seal. It's asphalt and aluminum. It'll stink a little at first but if you leave it in a warm, dry environment for a day, it should dissipate.

To reduce vibration from optical drives, you can also try to find some type of soft, pliable material (fabric, like felt, or thin foam works well) and wedge a small amount of it between the drive and the mounting points before screwing it down. It will reduce the bay vibrations quite a bit.
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Post by redtop » Fri Feb 01, 2008 5:52 am

Thanks for the replies guys.

Mike,

You would think that a nearly 5 year member would have a clue. So sorry you had to answer this same question for the up-teenth time! I didn't consider the suspension option and I haven't checked out the storage area on the forum for a while. I do check the SPCR site daily for new stuff. Guess I've gotten lazy in my old age... :D

I'm off to the fabric store today and may have a picture post of my own to add to one of the "stickies". Thanks for all of your great work here!
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Post by redtop » Fri Feb 08, 2008 11:25 am

Well, I completed the project last weekend. Here are the results...



Image


My main concern was HDD stability inside the case and operating temps. I am happy to report that the drive will not touch the case when moving it and runs very cool.

To facilitate the cooling, I foil taped over the vents at the front of the drive cage and the majority of the fresh air now enters the case from behind the drive. At idle Speedfan measures 32c in a 24c room. Under full load(defrag for an hour), only 35c... I can live with that... :-)

The best part is all case vibrations have disappeared, now the only sound is a gentle whoosh from my two 120mm fans running at 12v. I know I could undervolt them, but I would rather have everything running cooler at this point. I'm sure I will be experiementing with the fan speed next...hehe. Oh... and only about a $1.50 in parts to do it... :-)

Thanks to all and especially Mike. I shall be modding the other 2 PC's this weekend.

Brad
Last edited by redtop on Wed Apr 09, 2008 3:41 am, edited 1 time in total.
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Post by psyopper » Tue Apr 08, 2008 9:44 pm

I hate dredging up old topics but this is great stuff here!

Lou - thank you for the invaluable information. Is there any chance that you happened to test any of the butyl rubber linings? Or really - any of the solid structure materials (roofers tape etc)?

From looking at what you tested, specifically the AcoustiPak Countoured, which from what I can tell is 2mm (0.07") rubber and 15mm (0.6") foam and noted a 9dB reduction. I am wondering how much of this is attributed to the 2mm mass layer, the 15mm foam layer and the irregular surface shape.

I'm a DYI'er and am looking at varying ideas including bulk pyramid foam on eBay and butyl rubber sheets from GridLine Structures. I anticipate I can get the same effect (or potentially better) as the "real stuff" for the same price as a full kit while having enough left over (at least of the foam) to do about 20 more machines.

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Post by fnwtmp » Fri May 09, 2008 7:08 pm

What do you guys think of this? AcoutsiPack is $100 in Aus :(

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Post by toki_c » Sat May 10, 2008 2:08 am

fnwtmp wrote:What do you guys think of this? AcoutsiPack is $100 in Aus :(
Stay away from that...
Just go to whatever DIY shop, bigger one would be obviously better to got choice. You can find real cheap sound damping material... Sure it won't be designed to compuer usage. So you will find 5m rolls and such... But you will definitely got for your money.
I get mine to a nearby DIY shop, ~200m yes I know I'm lucky D: fro 20€, 5mx0.5mx7mm: 100% alleviation fro >3kHz, 89% for 2kHz, 69% for 1kHz...

Note: since then I said my farewell to seek noises and... I built my Sonata 3 with 2 layers, 1-2 layers a NSK3400 and there's still ~2m.
Yes, I do not have hdd enclosures. I have get rid of seek noises with even a "noisy" SE16 and a too vibrating Hitachi drive.
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Post by amyhughes » Sat May 10, 2008 4:44 am

toki_c wrote:You can find real cheap sound damping material... So you will find 5m rolls and such... I get mine to a nearby DIY shop, ~200m yes I know I'm lucky D: fro 20€, 5mx0.5mx7mm
What did you buy? What is this stuff called?

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Post by jhhoffma » Mon May 12, 2008 5:48 am

At that price, it wasn't anything too complicated. Most likely it was just asphalt-based deadening material. You can find it at Home Depot/Lowe's/etc as "Roofers Tape" and under trade name "Peel & Seal".

All sound deadening materials like this work pretty much the same, but the purpose-built ones don't work any better than the improvised ones and cost way too much, IMO.

It's possible he got a real awesome deal on butyl based materials (denser, no smelly asphalt adhesive) which work better (due to the density) but usually cost quite a bit more.

There are some other dampening threads around here with some more useful information, so have a look-see.
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Post by jessekopelman » Tue May 13, 2008 11:09 pm

jhhoffma wrote:It's possible he got a real awesome deal on butyl based materials (denser, no smelly asphalt adhesive) which work better (due to the density) but usually cost quite a bit more.
Butyl stuff has come way down in price. The eDead stuff is price competitive with Peel & Seal.

I think case dampening does very little for you if your system already uses quiet fans and drives. It certainly does little to quiet the spin noise of a 7200 RPM drive, which is likely to be the loudest thing if your fans are quiet and your drive is suspended or soft-mounted (which mostly takes care of seeks and writes). I'm curious how well the better internal HDD boxes do. Maybe having the damping right up against the noise source does the trick?

fnwtmp
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Post by fnwtmp » Fri May 23, 2008 7:09 am

http://www.dealextreme.com/details.dx/sku.12999

Just saw this :D I wonder if its any good? I've bought other stuff off the site before and they're pretty reliable... Its cheap.. and free shipping.. tempted.

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Post by JaYp146 » Fri May 23, 2008 8:44 am

fnwtmp wrote:http://www.dealextreme.com/details.dx/sku.12999

Just saw this :D I wonder if its any good? I've bought other stuff off the site before and they're pretty reliable... Its cheap.. and free shipping.. tempted.
Looks pretty similar to a foam-based bit of Cascade auto dampening I got from a guy @ Overclock.net's forums.
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fnwtmp
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Post by fnwtmp » Fri May 23, 2008 6:17 pm

So was it any good?

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