NO noise cabinet

Enclosures and acoustic damping to help quiet them.

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Johannes

NO noise cabinet

Post by Johannes » Sun Dec 01, 2002 6:15 pm

Hi,

Has anyone tried the new noise reduction cabinet at Plasmic?

www.plasmic.dk/cocoon

Does it work? and would you recommend it?



Look forward to hear your comments...


Johannes 8)

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Post by MikeC » Sun Dec 01, 2002 9:25 pm

hi Johannes,

This product is similar to the cabinets by Noren and Sound Construction & Supply Inc. listed on this web links page on our site: http://www.silentpcreview.com/modules.p ... ink&cid=16

The Norens seems like it would be the quietest; it is completely passive, does not use fans. The Sound Construction & Supply cabinets are more like Plasmic's -- they use fans. But pricing for both of these start at about double that of Plasmic.

Seems to me that you can get quieter (than the fanned cabinets) by following our DIY mods & projects with recommended products, or by buying complete PCs from companies like ARM, Pandora, or Captech (see under web links: http://www.silentpcreview.com/modules.p ... link&cid=9)

Guest

Post by Guest » Mon Dec 02, 2002 5:46 am

Hi Mike,

Thanks for your reply...but what I'm really interested in is to hear comments, experience and facts from people that have tried the COCOON cabinet (http://www.plasmic.dk/cocoon).

I have looked at the other URLs you gave me and I can conclude that I don't like the look of those cabinets. They are too colourful and "industryal-look-a-like" for my office. They also don't offer security for the PC like COCOON does.

I know the COCOON cabinet is a bit expensive and that is the main reason why I'm so eager to know if it works, before I go and invest that much money.

I think that buying a new silent PC from companies like you mention, would be the must expensive solution in the end for me becuase I frequently replace or upgrade my PC. I do 3D graphic and I need so much "power" as I can get when I'm rendering 3D-pictures. If I have to buy especially made silent products/(PCs) everytime I upgrade/replace my PC it would soon get very expensive. A cabinet from Plasmic or Noren gives me the freedom to replace my PC without considering the noise problem at all.


Look forward to hear comments!

BR

Johannes 8)

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Post by SungHyun7 » Tue Dec 03, 2002 10:28 pm

by using these products, i can't say what is is... but it just feels as though i'm cheating!! haha well that's just i.

we want ultimate silence... meaning we want it silent at the source... not just block it out with a cage...

or maybe it's just too simple... as we want to make things bit harder than what our wives can do :wink:

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Post by Melchior » Tue Dec 03, 2002 10:39 pm

Taking a look at that website, their solution is remarkably-similar to a design that I came up with a couple of years ago as part of a 4-th year project at UBC. The enclosure that I designed had its noise-reducing baffles along the right side of the case, whereas this Cocoon cabinet has it's intake baffle beneath the computer and exhaust baffle above the computer.

I can tell you that a noise-damping enclosures do work.

The enclosure that I built a couple years ago was made out of steel (it weighs ~100 lbs-- most-definitely theft-proof when the front cover's locked!). Steel's very effective at stopping sound, though it's a bit heavy and expensive. I do not know how effective wood is at blocking sound, though. Their noise measurements look quite promising, however a lot of their noise-reduction will come down to how well they can seal up the back of their case, where the cables come out-- it's bound to be the loudest part of the computer.

One other advantage about noise-reducing cases is that it's something of a one-size-fits-all easy-results device. No matter what components you have in your computer, such a case will quiet it down-- is your CD-ROM too loud when it spinds up? Good luck silencing it without putting the computer in a box!

The Cocoon is damn expensive, though. "ouch" is that word that floats through my mind when I think about their pricing... I hope the fit-and-finish is flawless...

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Nice but expensive

Post by powdersurge » Wed Dec 04, 2002 6:14 am

My idea of the Cocoon is more or less line with the other comments. I was really interested in this box... before sticker shock hit me :o

For that kind of money you can buy a LOT of "quiet" components: fans, PSU, HD, case, mats, ...

Yesterday I was looking into a product called Magic Vent (www.noisecontrol.de) that tries to reduce the white noise that escapes from the back of a PC. It's a kind of Magic Fleece treated enclosure that sticks on the back. It only fits on Chieftec mid and full towers at the moment.

Anyone tried that?

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Post by wussboy » Wed Dec 04, 2002 7:00 am

Melchior, I read your article about your cabint you built, and it was really good. In fact, it made me want to build my own cabinet. But I would love some information about the baffles that you built for your air intake. You wouldn't have any drawings or anything you could post, would you? I'd love to see any pictures you had or anything like that. I would like to build my own, but I don't want to have to reinvent the wheel if I don't have to.

Everyone: I checked out those pages about the custom cases made in the US, and they are really nice, but super expensive. Does anyone know: is it possible to build your own heat pipe solution? Can it be purchased from somewhere? It seems the perfect heat removal product for a quiet enclosure. Just wondering what thoughts were on this. Cheers!

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Post by hyum » Wed Dec 04, 2002 9:25 am

you can build you own heatpipe. quokked i think posted this link in another thread:

http://www.benchtest.com/heat_pipe1.html

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Post by MikeC » Wed Dec 04, 2002 9:53 am

Just to pitch in my 2 cents as usual:

I built a silencer cabinet ~1.5 years ago. My PC was already very very quiet,. I would guess 16~18 dBA. Maybe less. About as quiet as a Panaflo at 7~8V, sitting under my desk 3~4 feet away from my ears. But that was not good enough. I was seeking silence. You know, zero dBA!

Materials were massive medite board / 1" steel tubing frame plus various grades of damping materials such as carpet underlay, acoustic foam, insulation foam strips (around removable panels). The frame was built first, then the medite board screwed/glued to it. Door in front & back, and left side panel removable with large number of securing screws. It was ~ 28” tall, a foot wide and ~28” deep. Weighed closed to a hundred pounds.

The large left/right side panels were composites of 2 outer layers of ½” medite board & carpet underlay, all silicone glued / screwed. Other panels were a combination of ½”, ¾” and 1” medite board. Various types of damping material lined all the inside walls. (Different materials to try and get effective attenuation of noise at all frequencies. )

Carpet underlay covered the entire bottom of the cabinet so it was somewhat decoupled from the floor. Actually, the weight of the cabinet + PC was well over a hundred pounds, so there was probably too much compression of the carpet underlay for any serious decoupling effect.

Had an acoustically lined tunnel the width & length of the cabinet below the chamber where the tower PC sat. Large vent opening in back, large vent opening in front floor of main cabinet, directly under the front intake vent of PC. Outside air comes in from back bottom of case (at floor level) then goes directly where it is needed most, to the intake vent of the PC.

The interior chamber was deliberately sized so the PC would just squeeze in. This was to ensure that the incoming air would be forced to travel through the PC rather than be wasted just going through the chamber but bypassing the PC. The PC case was prepared by taking extreme measures to open up the vent holes front & back, to minimize impedance. The PC had a 5V Panaflo in the Enermax PSU. The Swiftech MC462A had a 5V Panaflo, too, over a 1G T-bird, undervolted / clocked to 933. Two aluminum sandwiched drives on bottom of PC case on foam: Barracuda IV & IBM 2 platter models.

There was a tunnel above the PC much like the one below. The opening was at the top back of the PC chamber. There was a space about 4~5” between back wall and back of PC, for wires. It created a tunnel for hot air to be exhausted from the PSU and the back panel vents, where it would rise and be drawn up into the tunnel.

The exhaust tunnel was where I made my big mistake. :cry: Instead of finding a way to duct the exhaust air out back in some kind of short acoustically damped baffle, I split the upper tunnel in 2 – running the depth of the cabinet. So the exhaust air had to come to the front of the cabinet then make a 180 degree turn and run back down the depth of the cabinet. This probably made the exhaust duct impedance too high.

A 92mm fan was positioned inside the cabinet at the entrance to the exhaust duct. It was the quietest one I had at the time, fed off an external DC power supply I made, along with a voltage regulator to adjust the fan speed.

It worked: the noise of the PC was greatly attenuated. Maybe by 6 dBA, maybe 8. But the price was 6~9 degrees increase in temps. Turning the tunnel exhaust fan on & playing with its speed helped a few degrees, but then made the noise level much closer to what it had been with the PC outside the case. Although the heat did not created instability, I was not comfortable with everything slowing baking in there, so I took to turning the fan up to full when I left the room & turning it down/off when I was working.

I abandoned the cabinet when I discovered that suspending the Barracuda gave a me a few dB improvement, and swapped the IBM for a second suspended Barracuda. These changes brought the PC noise level down to where it had been inside the cabinet. The cabinet took up too much space, made it hard to hack on the PC, and the background worry about heat was bothersome, so out to the garage it went.

Would I do it again? Only if I could do it fanless without increasing heat. If you look at the specs on the http://www.plasmic.dk/cocoon/en/datasheet.php datasheet, you’ll see they show a 4-6C rise in temps inside the cabinet too.

Silencing cabinets do have a useful place where:

1) existing PCs are not TOO loud but very expensive to replace and too difficult to modify
2) drop in quiet convenience is desired
3) absolute silence is necessary: the NORENS no fan cabinets make sense in studios & settings where there must be no extraneous noise at all (anechoic chamber??)

Hope that was worth 2 cents. ;)

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Post by wussboy » Wed Dec 04, 2002 12:53 pm

Awesome post, Mike. You addressed several issues that I was planning. I had planned on making both the top and bottom ducts like your top duct, but it seems this isn't such a great idea. I wonder how putting a couple devolted fans on the ends of the ducts would help airflow? With a 180 degree kink and the fans at the opening between duct and cabinet (not duct and the outside) their noise should be minimal, don't you think? I'm gonna check out that heatpipe article and see what that's about (thanks for that tip hyum). I think I'll build out of MDF, and have 4 case fans (80mm or 120mm panaflows at 7v) still, so that even though there is space around the case in the cabinet there should be good airflow through the case. Hopefully they will assist in total airflow through the cabinet, but be recessed inside the cabinet enough that their noise won't be audible.

If anyone else has thoughts about cabinets, I'd love to hear them.

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Post by MikeC » Wed Dec 04, 2002 1:19 pm

4 case fans (80mm or 120mm panaflows at 7v) still, so that even though there is space around the case in the cabinet there should be good airflow through the case. Hopefully they will assist in total airflow through the cabinet, but be recessed inside the cabinet enough that their noise won't be audible.
No way, IMO. That single fan in the duct was impossible to silence, even though it was buried in this massive damped case. Even suspended with rubber bands, I could always hear the airflow noise unless I turned it down so low that it was useless for cooling.

Why?

The air in any tunnel has resonant frequencies. Usually there are 2 peaks, if I remember right. The frequency and amplitude is easily calculated and measured. This is the phenomenon that ported speaker cabinet designers manipulate to aid bass performance.

Practically speaking, the effect of the tunnel to the noise of of the fan was to:

1) increase the amplitude at a certain frequency band. In my exhaust tunnel, it was somewhere high bass/low mid range.
2) decrease the amplitude at (mostly) higher frequencies.

Compared to the sound of the fan in open air, it went from a "sshhhhhhhhh" to a "ffooooooooooo". The latter was always more bothersome to me -- the open air sound is much closer to white /pink noise, which occurs in nature everywhere. Wind through trees, waves, flowing water in streams, etc. It is a sound we can accept more easily, because human beings have lived with it for umpteen generations. Part of our collectige genetic experience, so to speak. The second noise is more artificial, unnatural. My "theory". :roll:

If you are going to do fans, I suggest putting them on the exhaust side, and to make the "U-shaped or n-shaped tunnel" short, but very thickly lined with damping. Also make sure the cross section of the tunnels are at least 50% larger than the area of the fan -- double if you can.

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Post by Melchior » Wed Dec 04, 2002 5:02 pm

Mike, regarding the resonant frequencies of your ducts, that implies to me that your damping material may not have been particularly effective-- resonance only occurs if the sound *can* bounce back and forth to give constructive interference. If you can eliminate or nearly-eliminate the sound-bounces, resonance would be less of an issue.

Wussboy, because the 3/16" steel that I used for my enclosure was a pain in the ass to manipulate. As such, I haven't ever gotten around to finishing the enclosure-- the back is still wide-open. Since I've never sealed off the back of the case, I've never needed to install any extra cooling fans. While I was still using the case (before I installed Panaflos in my Athlon 1600+), I saw about a 6-8*C rise in temp between when I had the front of the case open or closed. When open, there was essentially no restriction to airflow whatsoever, since the back was open as well. When closed, if I put my hand over the air intake, I could feel a small current of air flowing-- the computer's fans were keeping the air flowing fairly well. Hmmm, might be an interesting weekend project to build a new noise-reducing case... If I have some free time at work tomorrow, I'll sketch up a little of what my case's design is like.

My enclosure's not perfect, but it does have some good noise reduction. It's about twice as wide as a tower case, and about 3-4" taller than my 17" case. As far as the effectiveness of my enclosure goes, with the missing rear panel, it did not make as big of a difference as adding undervolted Panaflos. My computer inside the enclosure was a little quieter than it is outside the enclosure with Panaflos at 12V. One difference that the Panaflos can't make up for is my DVD-ROM's noise. When I toss a CD in the drive, the drive at full speed is by a long shot my loudest component-- the enclosure made an immense difference in the amount of noise emitted by the DVD drive.

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tunnel resonance

Post by hvengel » Wed Dec 04, 2002 5:38 pm

The frequency of the tunnel resonance it dedendant on three factors.

1. The volume of the chamber connected to the tunnel.
2. the cross sectional area of the tunnel (speaker builders would call this a port)
3. The lengh of the tunnel.

The larger the chamber the lower the resonance frequency.

The longer the tunnel the lower the resonance frequency.

The smaller the tunnel cross section the lower the resonancy frequecy.

In speakers you are trying to create a resonant chamber that will couple the speaker cone to the outside air at a frequency that is about 1/2 octave below the normal cut off frequency (-3db) of the cone/box with out a port. So if the cut off freq. of the cone would be 100Hz than the port/ box would be tuned to arround 70Hz which would give a total system cut off freq. that would be around 60Hz or so. The roll of below the -3db point is 24db/octave.

This of course is not what we want to do to make a PC silent because the speaker builder is trying to INCREASE the sound levels in a specific frequency band. But it is instructive about the problems that Mike was talking about.

If you are not careful about understanding the chamber volume, port length, port area and the frequancies of the various noise sources installed in the "resonant chamber" and how these interact with each other you could in fact end up with more noise than you would otherwise expect or, in a worst case, even more noise than you started out with.

On the other hand if you clearly understand all of these variables it could be possible to optimize these to put the system resonance freq. at a point that did not respond to any of the noise sources and this could result in a very quite set up. But this is a non-trival problem as there could be dozens of variables to consider and all of these interact with each other and many may be hard to quantify.

In speakers there are 4 speaker vaiables plus the cabnet volume and the port area and length to consider. A total of 7 variables. These have been studied extensively and are now well understood (for at least 40 years). But even with this level of understanding 30 and 40 years ago there were many very poorly designed speakers on the market because the caluations needed to solve the problem were much too complex to do by hand. The 4 speaker variables are published by the speaker manufactuers and so the only variables that are of interest to the speaker designer are the last three. Now days you can download a number of shareware/freeware programs that will do the needed caluations in seconds and present you with the freq. response curves for the set of values you provide and in a few hours it is possible to have a design that is very close to optimum. The quiet PC cabnet problem is much more complex, has not been studied enough to be well understood and would require significantly more computing power to solve if it were understood well enough to solve.

On the other hand I do not think we should dismiss this solution because this or that combination of cabnet/ports/internal components did not give the result we had hoped for. It is just way too complex of a problem to expect that it can be solved by a few test systems with randomly selected components and dimensions.

Hope this helps.

Hal

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Post by MikeC » Wed Dec 04, 2002 5:57 pm

Hal and Melchior,

Thanks for your contributions to this discussion. :wink:

I should point out that the resonant effect I discussed was not big. I may have exaggerated to get across the point to wussboy about the challenge of silencing 4 Panaflos in a tunnel even at 7V.

In fact, my cabinet did reduce noise overall and I preferred the PC in the cabinet until I reduced the PC noise to where it was at the same level without the cabinet. The resonant effect was only audible in the duct where the fan was located. I think the damping material could have been better, but it wasn't bad.

It was when the overall noise level was the same in / out that the quality of noise with the PC in the cabinet became more objectionable to me (than with the PC outside).

But as I and others have noted here, as we approach silence, we all seem to get pickier and more sensitive...

Looking back at the original question in this thread, a typical 30-45 dBA PC is probably far preferable inside any of the PC cabinets we're discussing here -- home-made and commercial.

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Post by Melchior » Wed Dec 04, 2002 6:09 pm

Heh, this quest-for-silence has got to be some sort of a disease in itself. I've just ordered several more Panaflos from BG Micro (to silence other computers in the house that now annoy me as I walk near their rooms), and I'm realizing that my undervolted panaflo-cooled, harddrive-decoupled system isn't quiet enough-- I *know* I can do better! ...And thus, I must give it another shot and try to quiet things down urther...

...And to further promote the idea of a noise enclosure, I'll get weird looks from my friends: "what? weren't your computers quiet enough as it was? Now you're going to put BOTH your computers in a case? You're nuts!".

hehe, why so I am!

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Re: tunnel resonance

Post by wussboy » Wed Dec 04, 2002 6:52 pm

First of all let me start by saying I greatly appreciate all of y'alls input. This is incredibly valuable stuff that I can now be fore-armed with before blundering about on my own. Thanks.
hvengel wrote:The quiet PC cabnet problem is much more complex, has not been studied enough to be well understood and would require significantly more computing power to solve if it were understood well enough to solve.

Hal
When you first began to describe the problems of acoustic dampening, I was crestfallen because I know I don't have the brains to do the math required to build a quiet cabinet. Your above quote made me feel much better. :)

I guess my attitude going into this project is that I am going to build the quietest computer that I can (drive de-coupling, fan undervolting) and then put into the quietest cabinet that I can build/purchase. Several comments you made, Mike, made me curious as to why you didn't do this. You said you brought your computer out of its cabinet when you quieted other components. Why didn't you throw it right back into the cabinet?
Melchior wrote:Hmmm, might be an interesting weekend project to build a new noise-reducing case... If I have some free time at work tomorrow, I'll sketch up a little of what my case's design is like.
I hope you were implying you'd post those and let us take a peek? hint hint. :)

Thanks again gentlemen. I'm getting really excited about this. I'm sure you'll all be right sick of my endless questions before the [robot love] is unveiled to the world in all its splendor, but I'm sure it will be a fun ride.

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Re: tunnel resonance

Post by Melchior » Wed Dec 04, 2002 7:26 pm

[quote="wussboy"]
I hope you were implying you'd post those and let us take a peek? hint hint. :)
[/quote]

Of course! ...Actually, currently I'm thinking that after work tomorrow I'll make a run to Home Depot to see how expensive MDF or some other wood-like material is-- if I can afford to make it into a weekend project, I'll definitely do so, and I'll probably throw together a webpage about it, complete with pictures (I can borrow the digital camera from work!). My acoustic-absorbent material will be medium-density fiberglass ceiling tiles. They're only a few bucks per ceiling tile, and are excellent at cutting acoustic reflections.

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Post by MikeC » Wed Dec 04, 2002 8:04 pm

...and I'll probably throw together a webpage about it, complete with pictures...
Why not pass it over to us & become a famous SPCR like LeoV and Rusty? :wink:

wussboy, I was tired of having that big thing under my table/desk and I knew the temps would be up again, so that's why the cabinet is still in the garage. One day I'll convert it into a... center subwoofor for my media PC/TV setup! ( :roll: says the missus)

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Post by wussboy » Thu Dec 05, 2002 7:55 am

That just proves your not hardcore, Mike. Ha ha ha ha. :lol:

Melchior, look forward to seeing it. Cheers!

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resonant chambers

Post by hvengel » Thu Dec 05, 2002 12:49 pm

Mike and all,

I did not mean to imply that cabinets of this type would increase the noise levels althoug under exactly the right this could happen. But rather that if the noise properties of your components were well understood and if you had the right algorithms and enough computing power it should be possible to design cabinets that would have a huge impact on the noise level. This is simply something that you could not expect to have happen by trial and error unless you were very lucky.

As an example many years ago I built a noise reduction cabinet for a fixed location pump that was driven by a air cooled gas engine (think lawn mower). I was probably was very lucky but the pump could not be heard 30 ft away in a very quiet rural location (2 miles from he nearest public road). The noise reduction had to be at least 30db and I know people that have PCs that have higher noise levels. You could stand right next to the pump and have a quiet conversation. I used to delight in taking folks near the location of the pump. After asking them if they could hear anything and they said no I would walk over to the pump and open the enclosure. They were always astonished to see and hear the running pump.

The chamber/port combination acts as (I'm going to get technical) a 2nd order low Q band pass filter that rolls off at 12db per octave on either side of the pass band. So if you could place the pass band(s) of your system openings at least 2 octaves away from any of the systems internal resonances you would see a 24db noise reduction. If you could place this 3 octaves away you would see a 36db reduction. So in theory you could get a huge reduction in noise levels.

The problem is that the number of variables that need to be considered to approach these levels make this a very complex problem. It might be possible to simplify the problem by using a cascading set of chambers and ports so that they each cancel the others resonance. Still a non-trivial problem but one that might be solvable by someone that does not own a supercomputer and have a huge engineering and IT staff. In fact now that I think about this I remember seeing a set of drawings from a Finnish web site that had a PC cabinet design that used this type of setup. It might worth while to have another look at it.

Well this has been very interesting and Mike's observations about the resonance problem and the other person that made the connection of this to speaker ports made me think about this in ways I had not considered before. Thank you for making me think about this in this new way.

Hal

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Post by MikeC » Thu Dec 05, 2002 1:47 pm

Helmholz resonator, I believe is one engineering term for a tube with open ends. This makes me realize that I have a speaker box simulation design program called LEAP and/or CALSOD somewhere -- I think it runs in DOS!! -- that I could use to design the kind of box + tubes we're all talking about here. I think it could be modelled as an enclosure with dual ports (in/out). I'll have to see how to fudge the inputs needed by this program for the bass driver specifications. Could be a challenge.

But I don't think coming up with an effective PC silencing box is such a big challenge. I am quite sure it can be done by intuition and common sense, without huge engineering resources. (Misplaced trust in the obsessed hacker/modder?)

We know if a PC is made quiet, there is not that muich high freq noise, it is lower midrange and further down. We know that the larger the cross-section of the tube and the shorter the length, the lower the resonance peak (lower Q, to use spkr design terms). This also lowers attenuation on either side of the resonance; there has to be some reasonable balance between large tunnel cross section and noise reduction. A single 180 deg turn in a short wide streamlined tunnel might work best for the exhaust if it has to have a fan. No issue with the intake tunnel if it is not fanless. In my old box, there was no noise which emerged from the intake vent opening at the back / bottom.

It probably would help with cooling to remove both side panels from the PC you put in the cabinet. This would require thicker walls in the cabinet to make it soundproof enough.

Melchior (or someone): build not a partial solution but one that is silent & let's get it to market!! (Of course, the production cost must be under ~US$300. Steel sheets, medite board and acoustic foam with decoupling floor and super efficient 120mm fans or heatpipes? Must weigh under 200 pounds though :lol:

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Post by crisspy » Thu Dec 05, 2002 2:41 pm

I know it would cost more than $300, but for the price range of the other commercial solutions I would expect a beautiful double-walled, all glass aquarium with a seperate hinged front door (breeding tank?). The PC would thus act as an aquarium heater, evaporative cooling would eliminate the need for cooling airflow apetures, and suckerfish would keep the insides clean :wink: Alternatively, metal could be used for the inside walls (perhaps with an epoxy coated mural), thus facilitating heat transfer into the water. Our challenge would thus be shifted to finding a silent aquarium air pump and water filter. silentpc&aquariumreview

OK, I'm wrong, and I'll shut up now :) But hey, Be strong, be wrong!

AC blowers (sqirrel cage thingies) have two interesting properties that I'm aware of. First, they tend to have a very simple and constant tone. This might be easily cancelled by a properly designed acoustic trap. Second, they perform extremely well under high back-pressure operating conditions. This highly desireable trait should greatly facilitate the design of acoustic traps that are more capable and compact at the expense of airflow impedance. Third, they are typically designed for such high airflow that the smallest and cheapest of them would fall squarely in the airflow range needed for more than adequate system cooling. The fact that they are only usefully available in AC models poses a minor control problem that could be solved cheaply enough with a small relay or opto-isolated triac controller.

Anyone have any experience with blower noise cancellation?

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Post by SungHyun7 » Thu Dec 05, 2002 3:43 pm

aw... it was just getting interesting...

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Post by MikeC » Thu Dec 05, 2002 3:55 pm

Cris, that's a really good one, and not such an outlandish idea... Hmm I wonder how Betty feels about a fish tank... :lol:

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Post by Melchior » Thu Dec 05, 2002 8:13 pm

MikeC wrote: Why not pass it over to us & become a famous SPCR like LeoV and Rusty? :wink:
hehe, well, I picked up a carload of materials from Home Depot today. I spent 3 hours in HD! I think some of the staff there must've caught on the the fact that I was working on a nifty project-- I spent a good hour sitting on a stepladders next to the plywood calculating and planning things out on graph paper, making use of my Blackberry as an overpriced calculator (I suppose I could've pulled out my work laptop, but that would've really been overkill).

I'll build something up this weekend, and we'll see how it turns out, then I'll decide what my plans are with the setup. I've still got a few details to work out, then we'll see how useful it is. If nothing else, it'll cost me a fair bit less than the Cocoon would.

d_kay
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Post by d_kay » Fri Dec 06, 2002 2:43 am

I also took a peek on the finnish solution. ALthough I don't know any finnish it sure looked like he was on the right track. A Bass-port solution would be really cool.

But what if we can't make it completely silent?. Then what kind of noise is tolerable?. White noise surely, but once you put in some foam it will become more or less pink. The higher frequencies are the easiest to dampen, so I think it would be better to concentrate on the upper mid-range. glassfibre are a well-proven solution for that I guess, but it still is a broadband dampening solution, and I think we want something more frequency-specific. So Helmholtz resonators would be an interesting feature.

I'm going to measure the frequency characteristics of my PSU when I get back home. I'm a music producer/electrical engineer so this what I'm good at. :twisted: :roll:

wussboy
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Post by wussboy » Fri Dec 06, 2002 7:38 am

Something that has me thinking is that article about building your own heat pipe. With the meagerest of supplies and know-how, that guy managed to make the hot and cold ends different by less than 2 deg. C!! If that's the case, we could solve a lot of these "resonance" and "frequency" problems by just sealing the box completely, putting a massive heatsink apparatus at the top of the cabinet connected to heat pipes leading to a massive heatsink outside the cabinet. You could even direct a fan at the heatsink inside (it doesn't matter. It's all sealed). You loose 2 degrees in transferring the heat from inside to outside the cabinet. That seems a very reasonable price to pay for being able to completely seal the cabinet.

True, it will not fit under your desk anymore (well, it could if you put the 'sinks on the side), but think of the bonuses! You have a new plant stand/hat rack, and, oh yeah, your computer is completely silent!! Hell, you could even hook a water cooled system to cool the fins on the outside (put the pump inside the case and just pass the tubes outside). Damn, that's exciting. That's what I'm gonna do, methinks.

I love this thread! Some great ideas. I can't wait to see (or hear) how they all turn out. Cheers!

SungHyun7
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Post by SungHyun7 » Fri Dec 06, 2002 8:53 am

water cooling!!!

well... that's going to be my project.

completely sealed aluminum block + two hoses coming out to an external radiator.

atx form factor will also be sealed and i'll have all the connections made inside and just let the cables outside through a small hole + silicon seal.

what would be really cool is a completely passive radiator. perhaps a huge capacity a/c radiator from the junk yard??? well nah.... i don't wanna make my place too ghetto.... looks also matter much for me as much as silience. i like to keep stuff quiet, simple, small, and powerful in their decreasing magnitude of importance.

crisspy
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Post by crisspy » Sat Dec 07, 2002 7:31 am

About home-made heat pipes: I recently made a water based heat pipe with a good friend of mine in his small home metal shop. The basic procedure was as follows:

- made a metal pipe about 3/4" by 2' long with a ball valve on one end, as well as a small vacuum guage T'ed in just before the valve. We then had a reducer that we could screw into the ball valve outside and attach a small vinyl hose to. Copper would be best material for all this, we used stainless and weren't very happy with the results because stainless is a fairly good insulator.

- We filled about a half-cup of water into the pipe, then screwed on the hose adapter, and trailed the hose down into a bucket full of cold water sitting on the floor.

- Next apply the heat. We brought the water in the pipe to a boil, until it was rapidly bubbling steam into the water bucket below. After a little while boiling, all the air that was in the pipe had been purged, you tell because the steam bubbles instantly condense as they hit the water, whereas the air bubbles would rise to the surface. We boiled until there was no air left.

-Now stop the heat. As soon as water starts to suck back up the vinyl tubing, close the valve. You now have a heat pipe.

-What happens is the pipe is filled only with steam, plus a small amount of still liquid water at the bottom. When you seal it and remove the heat, the steam condenses leaving - you guessed it - vacuum. We hit about .9psi absolute. Water boils at about 100°f at that pressure. Not much use for computer cooling, but it's a start.

-These simple pipes have no wick, so they only run by gravity return of the liquid water.

-Next step is we are going to buy a compressed air ventury vacuum pump, used for purging automotive air conditioning systems. For about $45usd, you get a thing will draw down to about 85 microns. That's way below .8psi, where water boils at 32°f / 0°c. Yup, water's boiling point = its freezing point at just about .8psi . That's about 13.9psi vacuum. With the vacuum pump we can play around without the boiling stuff, wich doesn't work the best anyways.

Now as to whether or not heat pipes conduct sound, especially when you have enough of them to cool a case, I do not know. They are not a proper pure vacuum, and they are metal, so I have my doubts about their value as sound isolators. Especially using a bunch of probably large home made ones. I think their use is better for spreading concentrated heat like CPU's, and I bet we are only seeing the tip of the iceburg in that technology.

Keep up the good work on the cabinets guys, this is a pretty exciting thread.

d_kay
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Post by d_kay » Sat Dec 07, 2002 12:12 pm

what about dissipating heat into the floor?. Isn't that the coldest place closest to your computer?.

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