Damping material?

kasvad · Post by **kasvad** » Sat Mar 18, 2006 7:24 am

This question has probably been asked before, so please - forgive me.

I have an Antec P150 with a lot of empty space. I figured that some damping material could reduce sound and resonance from drives, fans etc.

Which material do I use?

Thanks in advance.

/Kasvad

m0002a · Post by **m0002a** » Sat Mar 18, 2006 7:35 am

You could use AcoustiPack. You can get it at http://www.endpcnoise.com

Trunks · Post by **Trunks** » Sat Mar 18, 2006 8:44 am

Acousti pack is nice. It comes pre sticky. But it is expensive. People here have luck with many typed of foam products. The Sonex Mini Willtec might look nice with your case it is also white. I really like “Audioseal” or Stinger “road kill”(pre sticky) because it is slick on top it does not muffle as much sound but it is cheap and very durable.

mkygod · Post by **mkygod** » Sun Mar 19, 2006 2:06 am

For vibration dampening, I would go for vinyl sheets that are similar to the ones pre applied to the p150.

Try to look for cascade VB-2MPC vinyl sheets which is a minipack that covers 4.5 sq feet and costs between 15-20 dollars. You may be able to find this at automotive stores. One place on the p150 that can really use it is the back of the motherboard tray, which is kindve flimsy.

For acoustic dampening, try Sonex wiltec foam. The cheapest place I can find it is from mnptech. THey have it for 7.99 per sheet (24x16x1in). But keep in mind they arent presticky, so you will have to invest in adhesive spray like 3M Super 77.

Shadowknight · Post by **Shadowknight** » Sun Mar 19, 2006 4:20 am

Instead of vinyl sheets, buy Vinyl floor tiles. You can get a package of 4 for $1 at most dollar stores.

Trunks · Post by **Trunks** » Sun Mar 19, 2006 12:05 pm

Shadowknight wrote:Instead of vinyl sheets, buy Vinyl floor tiles. You can get a package of 4 for $1 at most dollar stores.

I tried this…I bought some from lowes. (maybe they are to thick) I was not satisfied with the results. They did work some, but I got much better results from carpet foam.

jasonb885 · Post by **jasonb885** » Sun Mar 19, 2006 12:31 pm

Good question. I was about to ask something similar.

Anyone have any thoughts on these products before I buy all of them in pain?

At least one person here has commented that the asphalt stuff is nice insofar as it is heavy and helps weigh down cases, but can be smelly. The vinyl stuff is supposedly odor free. I'm also thinking about the foam itself, though probably for external use under each case and behind each case against the wall for the exhaust fan noise...

LIGHTWEIGHT VINYL SOUND DAMPING SHEET 10"x13"
http://www.partsexpress.com/pe/pshowdet ... tab=7#Tabs

ACOUSTIC FOAM 2-1/2" 24"x18" UL94
http://www.partsexpress.com/pe/showdetl ... er=260-515

ACOUSTIC FOAM 1-1/2" 24"x18" UL94
http://www.partsexpress.com/pe/showdetl ... er=260-516

I was also looking at these from McMaster-Carr (linking to their JavaScript stuff is fairly impossible):

http://www.mcmaster.com/ (search by item #, xxxxTxx)

9709T26
23.86
Viscoelastic Asphalt
0.050"
24" x 54"
0.13
-20° to +180° F
0.4
Black

9709T19
14.62
Polymeric Mastic
0.070"
32" x 54"
0.10
-30° to +300° F
0.7
Black

Thanks!

Trunks · Post by **Trunks** » Sun Mar 19, 2006 1:00 pm

I think with enough VE-1 ot Polymeric Mastic to cover the sides top, bottom, front and back of your case, and foam for the side pane with the right case you will be about as good as you can get, other that stuffing your whole case with foam.

I would compare the cost of that to the equal amount of the white foam, all over.

BrianE · Post by **BrianE** » Sun Mar 19, 2006 4:25 pm

Keep in mind that foam is (supposedly) for sound absorbtion, while heavy steel and vinyl sheets/tiles are for damping vibrations.

The closest thing I can easily find that sort of does both seems to be carpet underlay, but I don't know how effective it is (yet). Basically I'm always on the lookout for some foam that weighs a lot but isn't too hard or closed-cell...

theyangster · Post by **theyangster** » Sun Mar 19, 2006 5:25 pm

melamine is fine, nice and white

but fiberglas fibers aren't too fun

that sonex look promising though

jasonb885 · Post by **jasonb885** » Sun Mar 19, 2006 6:03 pm

BrianE wrote:Keep in mind that foam is (supposedly) for sound absorbtion, while heavy steel and vinyl sheets/tiles are for damping vibrations.

The closest thing I can easily find that sort of does both seems to be carpet underlay, but I don't know how effective it is (yet). Basically I'm always on the lookout for some foam that weighs a lot but isn't too hard or closed-cell...

So how do you know which you want to do?

Sounds like I should be using vinyl for under the case and foam for inside?

At the moment I mostly just want to stop the floor from vibrating from disks and fans. I haven't decided how much material, if any, I want to actually apply inside my case. One thing is for sure -- I don't want to apply the stuff that attaches via a magnet...

mkygod · Post by **mkygod** » Sun Mar 19, 2006 7:14 pm

Im buying vinyl and sonex foam. Going to layer the foam on top of the vinyl (where there is enough room). Maybe you should try the same thing and get the best of both worlds.

jasonb885 · Post by **jasonb885** » Sun Mar 19, 2006 11:47 pm

mkygod wrote:Im buying vinyl and sonex foam. Going to layer the foam on top of the vinyl (where there is enough room). Maybe you should try the same thing and get the best of both worlds.

That stuff is insane expense. Hence my questions about the items I posted earlier that seem far more reasonably priced.

For the cost of many 'silencing' items I've found it might just be cheaper to build a machine that's actually designed to be silent from the word 'go'.

Sigh.

Jay_S · Post by **Jay_S** » Mon Mar 20, 2006 7:28 pm

I've only been interested in silent computing for a few years, but have been building loudspeakers, audio equipment and tweaking my listening room as a hobby for over 10 years. Most of my "knowledge" comes from Dickenson's loudspeaker cookbooks and trial & error experiments. So maybe someone with an actaul engineering or physics background can add to or correct what I'm about to say.

There are only 2 things we can do to reduce acoustic energy: diffusion and absorbtion.

When we talk about sound we are talking about radiated acoustic energy. Acoustic energy is not ever really "absorbed", but is instead converted into other forms of energy. Usually this energy is heat energy (thanks to mr. newton). If you've ever opened a sealed loadspeaker you've probably seen loose fiber fill (acoustistuff, wool, pillow stuffing, etc). The stuffing reduces the overall internal acoustic energy by "wiggling" as the backwave passes through it, converting a portion of the backwave into heat energy. This "absorbtion" has the effect of making the enclosure "seem" larger to the woofer, because a reduced backwave is reflected back to the driver.

I know of no way to convert acoustic energy into heat energy, except through the use of fiberous materials. If you'd like to read some great material on absorbtion, see this commercial web site: realtraps.com. The owner also has some diy tutorials for those who would like to build their own panels. Keep in mind that they design and market products for rooms, not the insides of pc's and there are obvios differences (we sit in rooms, not in our pc's for instance).

Lot's of us (me included) stuff convoluted or eggcrate foam into our cases, thinking it will absorb or deaden the internal reflections. Here's a simple test - hold the foam up to your mouth. If you can breath through your foam, it will do NOTHING to either absorb or diffuse soundwaves. Sound will pass right through it and bounce off the panel behind it. I have foam under my suspended hard drive in case the bungee cords snap, not to absorb sound. The foam at the bottom of my case is covering wires (and I think it looks cool).

If you cannot breath through it (see better foam panels from auralex, RPG, etc), the egg crate foam will act as a diffusor, scattering the sound wave in many different directions, so that by the time it gets to our ears, it has only a fraction of its original energy. This link takes you to a thread from another excellent forum, scroll down for pictures of the ultimate studio control room - the definition of acoustic diffusion!

If powerful enough, acoustic energy can cause sympathetic vibrations in physical objects like pc case panels. This is resonance. Depending on its mass, a speaker diaphragm or pc case panel will tend to vibrate more at a certain frequency, called its resonant frequency. Adding mass to a panel will lower its resonant frequency. This is where your vinyl sheets and all the auto-sound dampening materials come in to play. Really manly-man mass loading could come in the form of 1/2 inch MDF panels glued to your internal case walls.

Then there's physical energy. Which brings be to my question:

jasonb885 "At the moment I mostly just want to stop the floor from vibrating from disks and fans"

Your hard drives and your case fans are vibrating your floors? Fan turbulence and disk whirring are both broadband noise, and shouldn't have enough energy to get your case panels resonating. So you're probably dealing with mechanical vibrations. Except for the dollar store vinyl floor tiles, I don't think mass loading your panels is going to be the most cost effecive solution for you. I would first try soft-mounting your fans and suspending your hard drives (with a spool or elastic, probably next to the floor tiles at the dollar store). You could also put carpet padding (try sorbothane feet for your case. Isolating and de-coupling your "vibrators" should be your first priority.

Spending $75 on acoustipack is murder and if your problem truly is mechanical vibration it will probably perform no better than vinyl floor tiles because - let's face it - their 2mm layer of "acoustic barrier mass" is not all that massive. The AcoustiContour convoluted foam is useless because (someone correct me here...) diffusion doesn't matter INSIDE a pc case. Our ears are not inside the case so direct & reflected path lengths are meaningless. A pc case typically has openings very close to the major sound offendors. Because they are so close to the openings, their noise is going to escape directly. Sure, some sound will also radiate inside, and the diffusors with scatter it around. But by this time, the directly radiated sound of your front case fan and hard drives has already escaped. So in my opinion, internal diffusion is irrelevant.

Diffusion foam would have a bigger impact OUTSIDE the case, if you were to cover all the adjacent walls and desk legs near the computer.

But again, I think you'll be better rewarded by isolating your, uh ... vibrators.

my .02,
Jay

Jay_S · Post by **Jay_S** » Mon Mar 20, 2006 8:57 pm

Actually, alot of this was already stated here.

mkygod · Post by **mkygod** » Tue Mar 21, 2006 6:04 am

jasonb885 wrote:
mkygod wrote:Im buying vinyl and sonex foam. Going to layer the foam on top of the vinyl (where there is enough room). Maybe you should try the same thing and get the best of both worlds.
That stuff is insane expense. Hence my questions about the items I posted earlier that seem far more reasonably priced.

For the cost of many 'silencing' items I've found it might just be cheaper to build a machine that's actually designed to be silent from the word 'go'.

Sigh.

It's normally very expensive, because most places sell them by the box for hundreds of dollars. You can just buy them by the sheet at mnptech for 7.99 ( 24" x 16" x 1" ). Two or Three of them should be enough for a P150.

http://www.mnpctech.com/SonexWilltec.html

It should be effective for absorbing frequencies above 1 khz.

jaganath · Post by **jaganath** » Tue Mar 21, 2006 6:33 am

I know of no way to convert acoustic energy into heat energy, except through the use of fiberous materials.

Completely off-topic, but another way would be to connect up a piezoelectric mic to a Peltier cooler.

For the cost of many 'silencing' items I've found it might just be cheaper to build a machine that's actually designed to be silent from the word 'go'.

Very true. As with a lot of consumer appliances, it's cheaper and easier to buy new than try and "repair" used goods. Of course, there are many on SPCR who like the "challenge" of silencing a computer which was put together with absolutely no regard for noise levels, but sometimes the effort expended in such an endeavour is disproportionate to the end result.

Shadowknight · Post by **Shadowknight** » Tue Mar 21, 2006 9:15 am

I went by a craft store today, and they carried a big roll of memory foam. It should provide enough weight to suck up vibrations and is thick enough to absorb acoustic noise. I would experiment, but it costs about $140

It's a really big roll, though, they just don't offer the foam in smaller rolls.

Post by **MikeC** » Tue Mar 21, 2006 9:27 am

kasvad's case is an Antec P150.

It already has a mass damping layer on each of the two sides. Any more is not likely to help, so I would suggest absorption panels are called for.

As for reducing vibrations, use the built in HDD suspension (with a HDD tray flipped over directly underneath in case the rubber ring breaks). It's the best way of eliminating HDD vibrations, which are usually the biggest source of vibrations in an already quiet system. Also play with decouple-mounting the fan/s with soft materials.

I've played w/memory foam -- its usefulness in acoustic damping for PCs is very limited.

TomZ · Post by **TomZ** » Tue Mar 21, 2006 9:29 am

jaganath wrote:
I know of no way to convert acoustic energy into heat energy, except through the use of fiberous materials.
Completely off-topic, but another way would be to connect up a piezoelectric mic to a Peltier cooler.

I don't see how that would work - a microphone produces microwatts, while the Peltier cooler requires several watts.

The basic problem is that the amount of acoustical energy available is tiny compared with the thermal energy being dissipated.

jaganath · Post by **jaganath** » Tue Mar 21, 2006 9:52 am

I don't see how that would work - a microphone produces microwatts, while the Peltier cooler requires several watts.

The basic problem is that the amount of acoustical energy available is tiny compared with the thermal energy being dissipated.

OK, so that particular example wouldn't work, but the general principle is sound (pun intended): it is definitely possible to convert sound energy to heat.

For example:

Acoustic Stirling Engine

Fridges of the future could be powered by a highly efficient engine that runs on sound and has no moving parts. Inspired by an invention of a 19th-century Scottish cleric, the Backhaus-Swift engine builds on the principles of the Stirling engine, invented by the Rev Robert Stirling in 1816, and first used to pump water out of a Scottish quarry. The "thermoacoustic Stirling heat engine" can convert sound into heat and vice versa. The sound levels generated in such devices, using specialised speakers, are extreme: in one case the levels reach 190 dB, about 10 million times as intense as the front row levels at a rock concert and 300 times the intensity needed to ignite human hair. However, the sound levels outside the rigid pressure vessel are acceptable. "They are not noisy because the casing is a quarter of an inch thick," said Backhaus, one of the inventors at Los Alamos National Laboratory.

Los Alamos Thermoacoustics homepage

Jay_S · Post by **Jay_S** » Tue Mar 21, 2006 1:16 pm

Yes, converting sound enery into heat is what wiggly fibers do (the stuff inside speakers and room absorbtion panels & bass traps). To do this, you'll need rigid fiberglass. Unfortunately, this is usually not available at your local hardware stores. Lumber yards and builder's wholesellers may be able to get it, but there will be a minimum order qty. And you'll have to wrap the fiberglass in something so the fibers don't get all over the insides of your case. I think this is one of the supposed benefits of MuteMats - you get the fiber layer. It's way too small however to be effective at low and low-mid frequencies, and their published specs confirm this.

Sound cannot travel where there are no air leaks. A completely sealed case with heatpipes for every hot component and non-resonating case walls is what I want. Or build something like this.

jaganath · Post by **jaganath** » Tue Mar 21, 2006 1:29 pm

A completely sealed case with heatpipes for every hot component and non-resonating case walls is what I want.

Like this you mean?

(OK, so it's not hermetically sealed but with a little work it could be).

Jay_S · Post by **Jay_S** » Tue Mar 21, 2006 2:59 pm

jaganath wrote:Like this you mean?

That thing looks far from sealed, there's holes all over the place. I'm thinking more along the lines of a huge power amp, but with a pc inside.

Trunks · Post by **Trunks** » Tue Mar 21, 2006 3:59 pm

Shadowknight wrote:I went by a craft store today, and they carried a big roll of memory foam. It should provide enough weight to suck up vibrations and is thick enough to absorb acoustic noise. I would experiment, but it costs about $140 It's a really big roll, though, they just don't offer the foam in smaller rolls.

Carpet foam ~ $0.24 a foot. Scraps are free. Memory foam does come in smaller sheets, like for pillows, but maybe not at your local place. Pillow foam is high priced compared to carpet foam.

BrianE · Post by **BrianE** » Tue Mar 21, 2006 5:28 pm

MikeC wrote: I've played w/memory foam -- its usefulness in acoustic damping for PCs is very limited.

Thank you for telling us Mike, I was also wondering about memory foam, given how dense it seems.

As far as low-cost foam goes, the cheapest stuff really does seem to carpet underlay. It's heavy, dense, porus on one side, but sealed on the other. I'm thinking of piling it up in multiple layers to see if it helps or not, but I'm still playing around with it so I might see how one layer does first.

I just wished most varieties looked a bit nicer.

Tibors · Post by **Tibors** » Tue Mar 21, 2006 6:56 pm

BrianE wrote:As far as low-cost foam goes

I'm getting a "new" couch this weekend. Guess what I'm going to do with the cushions of the old couch

Looking around a bit on the days they are collecting large trash can net you usefull stuff too.

Trunks · Post by **Trunks** » Tue Mar 21, 2006 8:43 pm

The Jay wrote:Spending $75 on acoustipack is murder and if your problem truly is mechanical vibration it will probably perform no better than vinyl floor tiles because - let's face it - their 2mm layer of "acoustic barrier mass" is not all that massive. The AcoustiContour convoluted foam is useless because (someone correct me here...) diffusion doesn't matter INSIDE a pc case. Our ears are not inside the case so direct & reflected path lengths are meaningless.

My experience with Acoustipack has been great.
I have a Sonata I case, replaced the PSU to one with a 120 mm fan. (covered holes) I had vinyl sheets all over in it. Normal hard drive mount (grommets) I could hear my video card fan, and hard drive. I suspended my hard drive, I could still here its slight whine.
I replaced the vinyl with pre-cut Acoustipack (when it was on sale ~$40). I left the vinyl I had on my slot covers.
Like I said the results were great. I could not hear the hard drive noises whine / spin noise, I unsuspended it could not hear the seek any more. My video card fan also became difficult to hear very, very low. My Optical drive is also noticeably more quit with the door closed its high pitched spin noise is a low growl.
Sound diffusion does help inside your case… that is the principle of padded baffles.

Felger Carbon · Post by **Felger Carbon** » Wed Mar 22, 2006 4:19 am

There's lots of ways to dampen cases. One way is mass loading.

Jay_S · Post by **Jay_S** » Wed Mar 22, 2006 6:32 am

Felger Carbon wrote:There's lots of ways to dampen cases. One way is mass loading.

Yes! Mass baby! I have lots of leftover dynamat xtreme from my cars doors and will be layering it up on my case side panels if I can find time this weekend. I'll post the pics and my thoughts on the effects when I'm finished.