# Computer resonator/muffler



## TEntel

If you seal the computer, you won't get any airflow.
You'd have to use water cooling, but then your radiator would still be noisy.


----------



## Slink

Well, of course. Why would I seal the computer? I'm talking about putting a muffler on the back (and probably on the front) and avoiding restriction of airflow.


----------



## purpleannex

The way to make a silent pc is to buy low noise conponents. You will never dampen the sound of air flow, only vibrations.

Buy a good case, and some low noise fans, you will be sorted. You don't need any loud (fast) fans with an underclocked 955, it will run cool anyway.


----------



## SalisburySteak

Don't use a coffee can for exhaust. It will start to sound like a riced out honda civic.


----------



## ez12a

mufflers dampen noise coming from a combustion engine...fans? i dont think that'll work nearly as well.


----------



## Brian_

you can't do that lol. where would you plan on having intake, this only works on cars because there is intake at front by radiator that cools the engine.


----------



## Slink

Well sure it would work because of the principles of acoustic noise cancellation, but is it feasible to have a big-a** resonator on the back & front? lol


----------



## purpleannex

Spend a couple of years trying different things out, then when you've still got a loud pc, buy a decent case and some quiet fans.


----------



## TEntel

Quote:


Originally Posted by *Slink* 
using a pipe-and-muffler system on a sealed computer.

I was quoting you, lol.

It is an interesting idea, but I think you're better off just investing in silent fans.


----------



## nategr8ns

Basically wrap the top/bottom/sides of the case in sound cancellation, like in-wall fiberglass insulation, and then make sure all of the air is exhausting through the back, where you can make sure it all goes through your resonator.

I doubt it will work very well, however, as the noise from the computer is much higher frequency than that of a car exhaust. I don't know if a resonator can even be made to muffle those frequencies.


----------



## hy897t

looking at your case. I would suggest better fans (Low-Med speed) and if you really wanted to use sound dampening I guess you could also use Dynamat and some rubber screws.


----------



## Core300

Submerged computer?


----------



## Slink

Quote:



Originally Posted by *TEntel*


I was quoting you, lol.

It is an interesting idea, but I think you're better off just investing in silent fans.


LOL touchÃ©. I meant to say "well-insulated case". *removes foot from mouth*

Quote:



Originally Posted by *purpleannex*


Spend a couple of years trying different things out, then when you've still got a loud pc, buy a decent case and some quiet fans.


I already bought fans that are pretty quiet, except for my jet engine CPU cooler.  They sure named it appropriately: "The Rocket" (Gigabyte cooler). Ugh.

Anyway, I have one of those mesh-front cases. They aren't so great. Noise comes out, and airflow is all which-way'd. 

I ought to just switch to TEC & Liquid cooling, and get it over with.


----------



## Slink

Quote:



Originally Posted by *nategr8ns*


Basically wrap the top/bottom/sides of the case in sound cancellation, like in-wall fiberglass insulation, and then make sure all of the air is exhausting through the back, where you can make sure it all goes through your resonator.

I doubt it will work very well, however, as the noise from the computer is much higher frequency than that of a car exhaust. I don't know if a resonator can even be made to muffle those frequencies.


 Sure it is. You just have to build to scale. I'mma draw something up real quick. BRB.

Quote:



Originally Posted by *GriZzlEnLS*


looking at your case. I would suggest better fans (Low-Med speed) and if you really wanted to use sound dampening I guess you could also use Dynamat and some rubber screws.


 Exactly, but I want to crank my gear back up. I have it dialed down because my current air cooling is inadequate.

Quote:



Originally Posted by *Core300*


Submerged computer?


Eh, that's another concept I'm working on. There are better ways. It's just so messy, however wonderfully effective it is.


----------



## purpleannex

Seriously, buy a better cooler. You don't even need good fans, buy any top end air cooler, and run your cpu fan at it's lowest setting, it will be fine at 2.8Ghz for a 955..


----------



## Slink

Quote:


Originally Posted by *purpleannex* 
Seriously, buy a better cooler. You don't even need good fans, buy any top end air cooler, and run your cpu fan at it's lowest setting, it will be fine at 2.8Ghz for a 955..

Yeah. Perhaps it's not worth the effort.

Here is a craptastic concept drawing I made.


----------



## dougc194

The muffler thing would work, but cases still leak a lot of sound. 
You would need a very strong & massive case, with minimal openings.

I would suggest building the case out of thicker metal, such as 1/2" steel, on all sides.

Also I have seen in wealthy homes, sometimes to build the woofer and sub woofer enclosures, they mold them with concrete, and build them into the walls of the media room.... Another option that might be easier to do (-than cutting and drilling thick steel plate-) would be to mold the case out of concrete, 1.5" or so thick. Concrete is very strong and heavy, and building the mold would only reacquire a few basic woodworking tools and materials. 
~


----------



## Slink

The concept seems "sound" (har har, pun) but I don't like the idea of a computer possibly being crushed by its own case. I think that lining a case with acoustic padding (and appropriate adhesive) would kill much of the sound transfer. Then there are rubber screws/washers/standoffs, etc. This would be a mod project...


----------



## CamiloOkB

I like the OP, he thinks out of the box. I say go for it and if it works let me know!


----------



## CamiloOkB

You never know he may be onto something here... Could make him a millionaire one day...


----------



## kwint

Use press and stick on the insides. Works as a replacement for sound deadening in cars, should work in a pc. You find it at your local hardware store.


----------



## chatch15117

Drill a couple holes in a moderately sized gun safe for water cooling tubes. The sound won't escape if you have your parts in a safe! Then put the radiator out the window or something.


----------



## pyra

Quote:


Originally Posted by *CamiloOkB* 
I like the OP, he thinks out of the box. I say go for it and if it works let me know!









I totally agree, I think it would be worth a shot at least and see what the difference would be. I would love to have some badass deltas in my case without all the noise.


----------



## Slink

Quote:



Originally Posted by *kwint*


Use press and stick on the insides. Works as a replacement for sound deadening in cars, should work in a pc. You find it at your local hardware store.


Nice tip. Thanks for the heads-up.

Quote:



Originally Posted by *chatch15117*


Drill a couple holes in a moderately sized gun safe for water cooling tubes. The sound won't escape if you have your parts in a safe! Then put the radiator out the window or something.











Yeah, that sounds more feasible than what I'm saying. LOL, still, I just want to test the concept...

Quote:



Originally Posted by *pyra*


I totally agree, I think it would be worth a shot at least and see what the difference would be. I would love to have some badass deltas in my case without all the noise.


Exactly. But then why do I bother air cooling?  This much work starts to become counter-productive, when I could sink a bit more $ and about the same time into a TEC+liquid rig.


----------



## dougc194

Most gun safes aren't real thick, believe it or not. Many are only two separate layers of 1/8" steel. Cutting in through the sides with an angle grinder+cutoff wheel(s) is no big deal. They use a real thick frame around the door to resist prying, and they make it _look_ like it's that thick all over, but it's usually not.

---------

Another possibly-easier type of "thick case" idea--use 3/4" plywood to build a wooden case that is double-walled, with 1 - 1.5 inches between the two layers, and fill in the interior space with sand. 
~


----------



## Slink

LOL sand!! That sounds like an awful thing to have near a computer.









Mmm sandyfans. Sound wave absorption and sound wave destruction are both important. I'd rather mod a factory case. That was the original intent of my idea. I think that I can get rid of all the intake fans, and just use ductwork for intakes. Hmmm... I could line the ducts with some sound-deadening foam.

This whole idea is starting to sound worse. :-/ I think there is a simpler way to incorporate acoustic "baffling" into the case intake and exhaust (as well as line the case walls with foam).


----------



## idontunderstand

I was wondering, instead of trying to muffle the sound, can you just get the sound further away? I mean what if you attached a dryer vent pipe to your case, then point it away, maybe another room. Maybe even out the existing dryer connection of the house if you are close enough to that. Heck, if you could attach it there, then you could even vent the hot air out of the house at the same time


----------



## Slink

Quote:


Originally Posted by *idontunderstand* 
I was wondering, instead of trying to muffle the sound, can you just get the sound further away? I mean what if you attached a dryer vent pipe to your case, then point it away, maybe another room. Maybe even out the existing dryer connection of the house if you are close enough to that. Heck, if you could attach it there, then you could even vent the hot air out of the house at the same time









That's a pretty darn good idea. I was thinking about something like this. Obviously I'd have to cover the exhaust with some screen so animals couldn't get into it, but I think this is the kind of simple, economical idea I'm looking for. I would probably wrap the vent tubing with some kind of sound-proofing.

Come to think of it, this would be a perfect opportunity to try to remove the fans from the case, and use one large exhaust fan outside, beyond the vent, to draw air thru the case (vented directly thru/across the individual component heat sinks). I'd just mount some simple exhaust housing outside the window. Hmmm


----------



## idontunderstand

It is strange that I was thinking of doing something like this myself. Except it wasn't for noise, it was for heat. My PC heats up the room in the summer. I was thinking of using Air Conditioning flexible tubing from the hardware store. You can get it insulated (so it should be quiet), and almost any length/width you want and you can flex it anywhere.

My problem is getting it to vent outside of the house.


----------



## TIGR

A lot of people are completely misunderstanding the concepts at work here.

"Sealed" system: this would be a system that is completely sealed _except_ for intake and exhaust pipes which provide airflow to the computer through "mufflers." Sound can find its way through _tiny_ holes, which could compromise this entire design. For this to work, air (and thus sound) must be allowed to travel _only_ where you want it to: through the intake/exhaust mufflers.

A resonator works, as mentioned, by reflecting sound waves in such a way that they cancel each other out; it's the same concept used to make "active" noise canceling headphones.

The use of materials that "absorb" sound (e.g. acoustic foam) convert the acoustic energy (sound) they absorb into heat. So they partially work against the goal here, but like with turbochargers (since we're combining automotive and computer tech in this topic anyway), you lose a little to gain a lot. Just keep this in mind when designing the layout and placement of acoustic foam (or equivalent).

Don't forget about structure-borne noise (vibration). There are two sources of this to consider:

Â· mechanical devices (fans and HDDs) transmit their own vibrations into whatever they are mounted to (this is why "soft mounts" are available for fans, PSUs, etc.)
Â· airborne sound (being a pressure wave) causes vibrations in anything it hits

This makes the entire thing (in our case, the computer chassis) vibrate, in essence becoming a _speaker_. The sound dampening mat often used to make cars quieter (most famously, DynaMat) generally works not by _blocking_ noise as many people mistakenly think, but by adding mass to vibrating objects; objects with more mass vibrate at a lower frequency, which to human ears sounds quieter.

But a potentially more effective solution is decoupling. Basically, this suggests building an "inner chassis" and an "outer chassis," between which lies anything (air, foam, etc.) that impedes the flow of vibration. Again with the cars/computers comparisons, Volkswagen has a patent for an acoustically decoupled car underbody, and Western Digital has one for an acoustically decoupled hard drive pivot bearing assembly. It is also the principle behind concrete "cavity walls," which are concrete walls that have an airspace between them (sometimes filled with insulation). In this case, that airspace is the decoupler (this is actually for both acoustic and thermal insulation).

So, with all that in mind, we could design and build an acoustically decoupled system that is sealed airtight with the exception of a single intake and single exhaust pipe. Between these pipes and the noise source, lie resonators which can create destructive interference, thus canceling out many of the sound waves without restricting _too much_ airflow. Such a chassis _could_ make a computer with a dozen 65dBA Delta fans sound like one with a few 20dBA fans.

Is it feasible compared to the competition? Depends. If you can't use KVM, USB, etc. extensions to remotely locate the computer, or the maintenance/risk of liquid cooling is unacceptable to you, possibly. It'd be _much_ more feasible for a company that could mass-produce a chassis incoorporating this setup than for an individual designing and building a one-off example.

This only touches on some of the basics behind the concept and there are many other concepts that could be combined with it, but hopefully it maybe it will get the gears turning for someone.

Edit to add: this would actually be much simpler than designing mufflers for cars. Car exhaust is an acoustically dynamic environment, with the frequency and amplitude of noise entering it changing as the engine is revved and put under varying load conditions. A computer using this design could be an acoustically static environment, with all fans run at 100%, all the time. Thus the resonator can be designed for that specific, unchanging environment, and do its job better than an automotive muffler can.


----------



## Slink

Exactly. Nice info, btw. Thank you. +1

Interesting point about the PC noise not being very dynamic, thus easier to predict and cancel by acoustic interference.

Only things that REALLY crank the dB are my CPU fan and my OSD drive (those are followed by case fans, etc.). Hard drive noise is are negligible compared to fan noise, unless perhaps they cause more structure-borne noise propagation.

It seems like there may be a better way to approach this. I think I would need to use TEC's on my hot components, and sinks on all RAM. I just don't see air as being the best primary medium for heat-dump. That is why they use liquid cooling. Also, I see fans as extremely detrimental to dB reduction. However, liquid cooling is also a pain, because let's face it: liquid+computers requires caution, etc.

Going with the TEC idea, I could use one TEC per hot spot (cpu, gpu, nb, etc.) and each could dump to a solid copper heat pipe. Each pipe would then lead to another TEC, all of which would then pump to a radiator mounted on the side of the case. If it works, that solves the fan noise & cooling problem. All that is left is to silently mount the drives, and a few near-silent fans for a little airflow thru the case. I can then use the muffling idea to kill most remaining noise.

Remaining concerns: "TEC temperature control" and "water condensation". Solutions:

lacquer the heck outta the boards
coat boards with petroleum or silicone jelly (yuck)
(ugh) oil immersion
automatic thermal cutoff switch for TEC's (when they are too cold) *I like this because it is a more elegant, energy-efficient solution.
seal the interior of the case (this means ZERO airflow) and dehydrate the air inside with a desiccant to avoid water vapor being available for condensation.


----------



## spartan2600

Quote:


Originally Posted by *TIGR* 
The use of materials that "absorb" sound (e.g. acoustic foam) convert the acoustic energy (sound) they absorb into heat. So they partially work against the goal here

I'm a physics undergrad in college, so I've done a little bit with soundwaves. The amount of heat generated by sound being absorbed by anything is incredibly minute. Even the noise from the space shuttle is not enough to register a noticeable increase in temp due to noise dissipating into heat.

Tigr has a point though about the two ways a computer can be noisy. The fan can vibrate what its mounted to, and the friction between the fan blades and the air causes noise too. Airborne sound can also resonate solids- the speaker effect tigr mentions. However, I doubt that sound from fans have the energy to do this.

The problem Tigr has is he is trying to apply sound-dampening techniques for cars to sound-dampening a PC. The physics is the same, but the specifics are not. Fan noise is high-pitched and has little energy (low amplitude). Engine noise, wheel noise, and resonances caused by the audio from the speakers cover the whole spectrum of what humans can hear (20-20K Hz) and has more energy (greater amplitude).

For pc's, we don't need to muck about with destructive interference to cancel out soundwaves or mass-loading or de-couplingto stop resonance. We only need to absorb noise.


----------



## spartan2600

I discovered this thread because I googled "PC muffler." I guess there haven't been as many interested in this idea as I'd thought. I already have all super quiet fans- I have never heard anything quieter than my Noctua fans (if there is anything quieter I have yet to hear about it). I also have the Zalman CNPS9700 CPU heatsink/fan. All of this is controlled by a Zalman MFC1 fan controller. I have used a Thermaltake Armor VA8000BWS case for a while now. The thing is fairly quiet, but I really want it silent...

So I started to do some research. I realized that the way the fans are on my old case would require me to muffler the entire front of the case to make it quiet. I looked at a lot of cases and found the new Corsair 700D to look the best. It takes air in from the bottom of the case so that airborne noise is absorbed by whatever is beneath the case.

I'm pretty scientific in my approach to things, so I tried some experiments. I covered the top, front and back of my case (all of which have intake/exhaust ports for fans) with pillows and thick blankets to see how much noise comes out the sides. The answer- hardly any. The only noticeable sound is when the hard drive is seeking. This makes me think that dynamat, or acoustipack or whatever is only really useful for eliminating the last 5% of noise. The bulk of the noise is airborne and comes to us through exhaust/intake.

Given all that, I will focus on first muffling the intakes/exhaust on my new case (which is in the mail at the moment). The bottom intakes already face down, so I just need to be sure that sound doesn't reflect off of what is below the case- particleboard in my situation. I might seal off the whole top exhaust. The back exhaust I will certainly muffle.

How to build a muffler? I'm assuming we've already found a good noise-absorbing material to cover the interior of the muffler in. Given that, we only have 2 priorities to keep in mind when figuring out how to configure the shape of the muffler's interior geometry. They are in order: be sure there is not a straight path through the muffler; maximise airflow. I've attached a rough drawing of such a design that is versatile and easy to make (the first attachment). You could either make it out of a cylinder and cut out 1/2 and 1/4 of it, and attach the two with 2 wavy-shaped pieces to hold it together (the second attachment), or 90 degree and 180 degree PVC pipes (the third attachment). The first implementation is slightly more work but could cover a square or rectangular exhaust/intake port- or maybe even an entire side of one case. The second implementation would just require two pieces of pvc tubing (besides the noise absorbing material) and could be used to muffle a circular exhaust/intake. There shouldn't be any need to add more length or bends to these mufflers assuming the absorbing material doesn't reflect noise. You could probably make a shorter muffler with fewer/shorter bends if the muffler is aimed at something that absorbs noise, like a carpet. However, the attached designs should do all the noise-absorbing themselves.

I'll let everyone know when I build these. Also, if anyone has suggestions I'd be glad to hear them!


----------



## spartan2600

Oh yeah, here are the links to my equipment.

Current case:

http://www.newegg.com/Product/Produc...82E16811133154

Future case:

http://www.amazon.com/Corsair-Obsidi...0738753&sr=8-2

other stuff:

http://www.newegg.com/Product/Produc...82E16811999171
http://www.newegg.com/Product/Produc...82E16835118019


----------



## Mastiffman

Quote:


Originally Posted by *Slink* 
Well sure it would work because of the principles of acoustic noise cancellation, but is it feasible to have a big-a** resonator on the back & front? lol


Ignore the Noise coming from this thread and Go for it. Who knows you may end up with a patented idea one day and be laughing at all of the guys who said "quit wasting your time using your brain and just go fill someone elses pocket....."









Look at all of the BS products that many Enthusiasts buy because they want to. Maybe some day they'll be buyng something that you invented.... Maybe not something completely necessasry... But really...... Are any of the products that we buy completely necessary?









Quote:


Originally Posted by *spartan2600* 
Oh yeah, here are the links to my equipment.

Current case:

http://www.newegg.com/Product/Product.aspx?Item=N82E16811133154

Future case:

http://www.amazon.com/Corsair-Obsidian-Aluminum-Enthusiast-CC700D/dp/B003AM8QH4/ref=sr_1_2?ie=UTF8&s=electronics&qid=1280738753&sr =8-2

other stuff:

http://www.newegg.com/Product/Product.aspx?Item=N82E16811999171
http://www.newegg.com/Product/Product.aspx?Item=N82E16835118019http://www.newegg.com/Product/Produc...82E16835118019

You're gonna buy that pretty smooth case and get a panel full of Nobbs sticking out of it? Get a digital one....


----------



## spartan2600

I used to have a digital fan controller (by sunbeam). Maybe it was just a crappy controller, but it made me hate digital controllers. I shouldn't have to push 4 buttons to speed up a fan. The controller I have now is 6 nobs, quick and simple. I don't have to navigate menus or adjust settings or set the date and time... blah blah blah.

Is there a good digital fan controller you can suggest?


----------



## punker

Quote:


Originally Posted by *Slink* 
Hi, all. I'm just musing whimsically about making my PC shut the heck up. It's pretty loud.

Intro: Automotive mufflers/resonators acoustically reduce decibel/volume levels from engine exhaust noise by way of destructive interference (sound wave cancellation). This works by piping the sound into a resonator chamber that, when appropriately-sized to suit the amplitude and frequency of incoming sound, will reduce the amplitude of any sound waves before they can exit the chamber (the exit end opposite from the entrance end) effectively deadening the sound from the noise source.

Now, I know people have made all kinds of wacky sound dampeners (that absorb sound waves with soft material such as foam) and that method would probably be useful in conjunction with my idea here, but I can't seem to find anything about people using a pipe-and-muffler system on a sealed computer. I think that if I lined the case with acoustic/dampening foam, and piped the output thru a resonator, I could kill about 80%-90% of the sound from the computer. (rough guess)

I was considering using a coffee can or something, and some pipe. It would probably be appropriate to make a multi-chambered resonator, to have small enough chambers that they are appropriate for the incoming sound waves, but also allow enough airflow thru the muffler to effectively cool the PC system.

Opinions, please!! Hope you find the idea intriguing!

the noise from a pc does not bother me

not any more

i am so used to it

if the computer is off it's hard to sleep

just to annoy people sometimes i turn on my 20mm 25,000 rpm fans(5 of them) 85db..... ouch

only puts out a whopping 8CFM each fan

they will chop off your finger if your not careful


----------



## spartan2600

20mm fans? Those are some tiny fans.


----------



## Slink

Quote:


Originally Posted by *spartan2600* 
I'm pretty scientific in my approach to things, so I tried some experiments. I covered the top, front and back of my case (all of which have intake/exhaust ports for fans) with pillows and thick blankets to see how much noise comes out the sides. The answer- hardly any. The only noticeable sound is when the hard drive is seeking. This makes me think that dynamat, or acoustipack or whatever is only really useful for eliminating the last 5% of noise. The bulk of the noise is airborne and comes to us through exhaust/intake.

Glad you found my thread. I like your airflow ideas.







I tried the very same thing with pillows, and noticed the same. However, my case literally vibrates from OSD and HDD spinup, so I'd need to pad the case junctions (I might be able to just use silicone caulk). I wonder how much sound is transferred thru the PC window... I like to be able to see my PC's perdy guts.

Anyway, what do you think about active noise cancellation for crazy loud fans? "Sounds" expensive.

The more I think about this muffling idea, the more I think that liquid cooling would be a more worthwhile solution. However, if the inside of the case were covered in dynamat or whatever, things would be quieter. Ironically, this issue isn't as pertinent in the summer because I run my fairly-loud AC unit. lol

Quote:


Originally Posted by *spartan2600* 
I used to have a digital fan controller (by sunbeam). Maybe it was just a crappy controller, but it made me hate digital controllers. I shouldn't have to push 4 buttons to speed up a fan. The controller I have now is 6 nobs, quick and simple. I don't have to navigate menus or adjust settings or set the date and time... blah blah blah.

Is there a good digital fan controller you can suggest?

Agreed. I vote analog. Digital = remote power control = more things to self-break/wear out eventually. A direct analog controller is all that is necessary: Simple, elegant, effective, and inexpensive. You can build one from scratch (tho I'd rather buy the potentiometers). You could even mount it outside of the some acoustic insulation.

Quote:


Originally Posted by *punker* 
they will chop off your finger if you're not careful

lawl.

Quote:


Originally Posted by *spartan2600* 
20mm fans? Those are some tiny fans.

lewl.


----------



## spartan2600

Its an interesting question- whether window's allow more or less noise through than a typical aluminum/steel side. I'll test that out, I'm pretty sure my side window-panel and the solid aluminum ones are interchangeable. Will post what I find.

I'm not even sure how active noise cancellation would work. You would probably have to be a sound engineer just to know what to do, and its probably all overkill. Just buy some quieter fans or like you say, switch to water cooling.

I have researched water cooling for probably 7-8 hours... I wish I was joking. It seems there is no feasible and decent fanless water cooling solution. The closest thing that comes to that is the Zalman Reserator 1 V2, but there are many problems with it. The pump is weak and often fails but worst of all, is nearly impossible to replace. Also, Zalman reps have stated the Reserator 1 is not sufficient enough to cool many modern systems, which is why they came out with the Reserator 2 and Reserator XT- but both of those have even more problem and were all cancelled. Only a few retailers sell what is left of the old stock. I also looked into making my own fanless system (like using 2 quadruple fan radiators, etc) but that seems very risky and expensive.

After finding all this out, I looked into the next quietest thing- water cooling *with* a fan. It looks like swiftech makes some good kits, however they cost nearly $300. I figured I might do that later, but muffling my PC will be cheaper, possibly quieter (though it wouldn't cool as well as water would) and even if I go to water-cooling, muffling will still benefit me. Also, I just got a couple NoiseMagic NoVibes III in the mail and installed them. They are fantastic! I had some Scythe hard drive "silencers," but they were useless- a waste of 21 dollars (they were like 7 bucks each). They couldn't even stop the HDD's from rattling against the case. I can still hear my HDD if everything is quiet, but I think it isn't the fault of the Novibes. I would probably have to cover the drives in Acoustipack to totally silence them. Speaking of acoustipack, I just got some in the mail, and will test that out with everything else I'm doing.

Just to keep people abreast of what I'm doing:
I went to my local Menards (its like Home Depot for Wisconsin). I bought a few pvc pipes, some carpets and other things that look useful for killing noise. I realized that the 180 elbow + 90 degree elbow system I have diagramed above is overkill. Instead, I went with a single 90 degree elbow. It seems that is all I need to kill most sound, and what sound does pass through I can aim downwards into the carpet below the PC tower. I am testing out this design, and comparing a couple different materials.

I came up with one more alternative design however. I would take a pipe 9 inches in diameter (the width of my pc) and as tall as the tower, and cut that pipe in half dissecting it vertically or length-wise. Then this semi-cylinder would cover the back of the entire case. This would allow easier airflow, and as an added bonus, cover all my wires dangling off the back. The problem with this is finding a pipe 9inches in diameter. Also, I'm not sure if I'd have to cover the top and/or bottom openings to eliminate all the noise.


----------



## Slink

Quote:


Originally Posted by *spartan2600* 
I came up with one more alternative design however. I would take a pipe 9 inches in diameter (the width of my pc) and as tall as the tower, and cut that pipe in half dissecting it vertically or length-wise. Then this semi-cylinder would cover the back of the entire case. This would allow easier airflow, and as an added bonus, cover all my wires dangling off the back. The problem with this is finding a pipe 9inches in diameter. Also, I'm not sure if I'd have to cover the top and/or bottom openings to eliminate all the noise.

Window vs. metal side : ok

Noise cancelling: not really feasible

9" pipe: why not just bend some material to make your own half-pipe? Otherwise, you have a good idea, imo. Like, Really good. So simple. You could take any kind of plastic, and hit it with some heat gun goodness to make it pliable so you can bend it. If you know what you're doing, you will get a nice uniform curve, without making blemishes or starting fires. ;-P Maybe make a curve guide/template. Frankly, I'd rather just get some flexible plastic, such as vinyl.

My PC case is mostly mesh or vents on front and back, so I would need one of these rounded shields for the front and one for the back. I would carpet the inside of the shield. In lieu of duct tape, I would have to affix latches/hinges of some sort onto the side of the case, or use hook-and-loop (Velcro), or interlocking tape (like 3M's Dual Lock). We could then take it a step farther by putting a hood over the end. See attached illustration:


----------



## spartan2600

Quote:


Originally Posted by *Slink* 
You could take any kind of plastic, and hit it with some heat gun goodness to make it pliable so you can bend it. If you know what you're doing, you will get a nice uniform curve, without making blemishes or starting fires. ;-P Maybe make a curve guide/template. Frankly, I'd rather just get some flexible plastic, such as vinyl.

Excellent idea! Just got the new case. This thing is monstrously large.


----------



## Slink

Thanks. Attachment updated a bit.


----------



## deafboy

lol. I have muffler...did it from back in the day of The Screen Savers when Yoshi built the silent PC. Works very well.


----------



## Slink

Quote:


Originally Posted by *deafboy* 
lol. I have muffler...did it from back in the day of The Screen Savers when Yoshi built the silent PC. Works very well.









Pics please!


----------



## deafboy

I don't have any pics of mine, took it off a while back after I put my fan controller on.

pretty much just like the one in the video though but for a single 120 fan...

http://video.google.com/videoplay?do...8907974334180# @ 7:20


----------



## Slink

Quote:


Originally Posted by *deafboy* 
I don't have any pics of mine, took it off a while back after I put my fan controller on.

pretty much just like the one in the video though but for a single 120 fan...

http://video.google.com/videoplay?do...8907974334180# @ 7:20

Thanks for the post. It's good to see some of the ideas applied.

See after 6:30 for some material info. ^_^ WOW, ONLY 15dB BELOW 100Hz, AND 8dB ABOVE 100Hz!!

I think we're really onto something effective and simple with covering the front/back panels with this "insulated pseudo-half-pipe" idea.


----------



## spartan2600

What did he make the muffler out of?

I went to the website they linked to soundsuckers.com, and the only way to buy melamine is in bulk quantities costing $300 or more, and at hundreds of square feet. Where can I buy materials in the smaller quantities I need?


----------



## spartan2600

What did he make the muffler out of?

I went to the website they linked to soundsuckers.com, and the only way to buy melamine is in bulk quantities costing $300 or more, and at hundreds of square feet. Where can I buy materials in the smaller quantities I need?


----------



## Slink

Quote:


Originally Posted by *spartan2600* 
What did he make the muffler out of?

I went to the website they linked to soundsuckers.com, and the only way to buy melamine is in bulk quantities costing $300 or more, and at hundreds of square feet. Where can I buy materials in the smaller quantities I need?

I found this one via google search: http://www.fractal-design.com/?view=product&prod=24

Watching the video, the man, "Yoshi" of "The Screen Savers" used Dynamat foam inside the case on the panels, and then layered "Akasa Paxmate" (found in the Case Accessories section of Akasa group's web site). Also used was melamine acoustic foam. As you may already understand, it's very important to maintain good airflow, as this foam will also insulate heat from being conducted through the case panels toward the outside of the case.


----------



## Slink

Two hours later...

The muffler looks like it was made of metal or plastic, with some foam lining on the inside. (AFAICT)


----------



## deafboy

fyi... "magic erasers" are melamine foam. not sure what the difference between standard melamine foam and the melamine acoustic foam is.


----------



## Slink

Quote:


Originally Posted by *deafboy* 
fyi... "magic erasers" are melamine foam. not sure what the difference between standard melamine foam and the melamine acoustic foam is.

Acoustic foam (in ancient fables as "ackoustick foame") is a specially-formed variety, where the spatial properties of the bubbles contribute to the magical sound-absorbing effect. (AFAIK).


----------



## TIGR

You want "open cell" foam for absorbing sound.


----------



## deafboy

Lian-Li did it...lol


----------



## Slink

Quote:


Originally Posted by *TIGR* 
You want "open cell" foam for absorbing sound.

Troof. Thank you.

Quote:


Originally Posted by *deafboy* 
Lian-Li did it...lol

Thank you, too.


----------



## GingerJohn

Quote:


Originally Posted by *spartan2600* 
....I have researched water cooling for probably 7-8 hours... I wish I was joking. It seems there is no feasible and decent fanless water cooling solution. The closest thing that comes to that is the Zalman Reserator 1 V2, but there are many problems with it. The pump is weak and often fails but worst of all, is nearly impossible to replace. Also, Zalman reps have stated the Reserator 1 is not sufficient enough to cool many modern systems, which is why they came out with the Reserator 2 and Reserator XT- but both of those have even more problem and were all cancelled....

@Spartan2600

I realise that your post was 4 weeks ago, but I thought this might be of some help (possibly a little OT for which I apologise).

I have a Zalman Reserator 1 V2 and I like it, after a few alterations. You are right about the pump being weak, and being VERY hard to replace. Iâ€™m sure you read that unscrewing the base was the hard part; I used some ropes, pulleys, sticks and a small carthorse and it still took me all night, but it is doable. I replaced the pump with a 12V EK-DCP 2.2 (located inside my case), which is inaudible once I decoupled it from the case with Petra Tech gel stuff.

As for not being sufficient to cool a modern system, I have mine hooked up to an i7 860 (OCâ€™ed to 3.7GHz, canâ€™t remember the vcore) and an HD 5850 with EK full cover block (recent addition) and it runs OK. I am cheating in that I also have a XSPC RX120 radiator attached to the case exhaust fan. As far as temps go, it runs hot when doing a long CPU burn / Furmark run (80C ish on CPU, 50C ish on GPU), but everything is still stable. I have not really had chance to play with it in itâ€™s current state (and I am working away from home at the moment) so I canâ€™t give you exact temperature numbers.

I know the Reserator 2 was cancelled due to many issues, as you said, but I thought that the XT was still going strong. It has a fan though, so you are back to square 1 with that.

If you are still thinking of passive water-cooling it may be worth looking at these:

http://www.alphacool.com/index.php/c...Radiators.html

They seem to be reasonably cheap, fan-less and modular, so you can always add more sections if you need to (CPU upgrade, extra GFX card etc). No idea how they would perform in service though!

I really like your idea for the whole case muffler; cheap, easy and hopefully effective. I will be watching with interest to see how this works out.

John


----------



## spartan2600

Thx for the detailed info gingerjohn! I will have reconsider the reserator. Regarding the muffler, I've been slacking on it. I covered virtually every square inch of the inside of my case with acoustipack, which helped a lot. I've been slacking on building the muffler though. I did decide that a Screensavers-style muffler would be better than my PVC tubing since I can't get any 14 cm diameter tubing, and the elbow tubes take up too much room. I'd have to move my computer desk further away from the wall for that (my room is very cramped). I also bought some HFW-1" (Mini Wedge) on this site:

http://www.silentsource.com/afoams-hushfoam.html

Which I bought too much of (3 massive sheets), so if someone wants to buy some from me, let me know. I'm going to use this in my case, and possibly the muffler.


----------



## ascaii

nevermind^^


----------



## Serifus

I had seem someone do something fairly similar to what you are describing in a completely different manner though it was for a mini-itx system. http://www.mini-itx.com/projects/decobox/ if you would like to check it out


----------



## Slink

For anyone interested, I will eventually be pursuing this project in the near future. Subscribe for updates. Thanks. -Slink


----------



## Manyak

Quote:


> Originally Posted by *Slink;13050424*
> For anyone interested, I will eventually be pursuing this project in the near future. Subscribe for updates. Thanks. -Slink


Good luck, but from reading this thread it's pretty obvious you don't know what you're getting into by trying to make a muffler.

Just look up computational fluid dynamics and you'll see what I'm talking about.


----------



## Slink

A person doesn't need a training in fluid dynamics (let alone CFD) to achieve *basic*, passive acoustic cancellation & baffling (but I'm sure it would help).

EDIT: I think it is really going to use more sound absorption than wave cancellation anyway. The goal is to understand how waves bend around edges, and to intercept them directly via "insulation", and also to bounce them directly back toward their source. (The latter will work for constant sounds such as fan noise, etc.)


----------



## BradleyW

Good quality fans are the best option. Also, a good case makes all the difference. Fan controllor will also make a huge difference.


----------



## Manyak

Quote:



Originally Posted by *Slink*


A person doesn't need a training in fluid dynamics (let alone CFD) to achieve *basic*, passive acoustic cancellation & baffling (but I'm sure it would help).

EDIT: I think it is really going to use more sound absorption than wave cancellation anyway. The goal is to understand how waves bend around edges, and to intercept them directly via "insulation", and also to bounce them directly back toward their source. (The latter will work for constant sounds such as fan noise, etc.)


Nah sound absorption is easy, yes you can do that. But to design a muffler that makes sound cancel _itself_ out is a whole different story. Sound waves are actually variations in atmospheric pressure, and if you want to control them like that it's a lot more complicated than just putting a can on a pipe. You can actually end up with the opposite effect, where the "muffler" ends up making the sound even louder, if you don't know what you're doing.

Either way, cars and computers are two completely different things. Mufflers work on cars because the sound waves are caused by the pressure of the pistons expelling the exhaust, and so the 'waves' of high/low pressure are nothing more than the exhaust moving straight through the pipe. In other words, it's unidirectional. With fans, the sound comes from a) the vibration of the fan motors, and b) the turbulence of the air moving across the blades. Both sources cause the sound to be expelled in all directions. So your only chance here is to either reduce their pressure (use better designed and/or slower fans), or to absorb them.

But you still have to exercise caution with baffles too. Every "turn" the air has to make causes additional noise. If you want a high-flow system (which you'd need for high end parts), you have to make sure that air pressure is as close to equilibrium as possible with every turn, otherwise you'll be wasting your efforts.


----------



## Slink

Quote:



Originally Posted by *BradleyW*


Good quality fans are the best option. Also, a good case makes all the difference. Fan controllor will also make a huge difference.



"Large fans only" rule, plus "good fans only" rule = _quiet fans only!_ This includes the CPU cooler fan.
.
Anything motorized (fans, drives) should be mounted on soft (rubber/foam) mounts to avoid case vibration/reverberation.
.
Solid state disks (SSD) should be used instead of motorized hard drive disks (HDD) to eliminate some motor noise.
.
Must have a quiet optical disc drive. They are REALLY noisy compared to most other computer parts. I'd probably dismantle the OSD case and insulate that with rubber grommets.
.
If you're like me, you notice high-pitched sounds. Often, graphics cards emit annoying squeaks/squeals with GPU processing. I'm not quite sure how to approach this besides using sound insulation (which easily stops high-frequency waves). The may complicate GPU cooling.
.
Metal panels & framework will be encased in acoustic insulation.
.
Metal panels will have holes drilled & filled to break up the reverberative continuity. (Example: get 2 flat, metal panels, and in one of them, drill a matrix of holes where you can't draw a straight line from any one point on the edge to any other edge, without losing too much of the panel's structural integrity. If you strike the holey panel, it will reverberate much less than the unaltered one. NOW fill each hole with a soft rubber grommet/stud: big difference.)
Note: It's important to preserve the case's electrical grounding. All that baffling will lead to static if not well-grounded.


----------



## Manyak

Quote:



Originally Posted by *Slink*


"Large fans only" rule, plus "good fans only" rule = _quiet fans only!_ This includes the CPU cooler fan.


The "large fans only" rule is bs. Achieving the same static pressure with a large fan requires larger blades and a larger motor. The larger the motor, the more vibration noise it induces.

It's about balancing the fan size with the amount of air you want to move and the amount of static pressure you need to move it.


----------



## Slink

Quote:



Originally Posted by *Manyak*


Nah sound absorption is easy, yes you can do that. But to design a muffler that makes sound cancel _itself_ out is a whole different story. Sound waves are actually variations in atmospheric pressure, and if you want to control them like that it's a lot more complicated than just putting a can on a pipe. You can actually end up with the opposite effect, where the "muffler" ends up making the sound even louder, if you don't know what you're doing.

Either way, cars and computers are two completely different things. Mufflers work on cars because the sound waves are caused by the pressure of the pistons expelling the exhaust, and so the 'waves' of high/low pressure are nothing more than the exhaust moving straight through the pipe. In other words, it's unidirectional. With fans, the sound comes from a) the vibration of the fan motors, and b) the turbulence of the air moving across the blades. Both sources cause the sound to be expelled in all directions. So your only chance here is to either reduce their pressure (use better designed and/or slower fans), or to absorb them.

But you still have to exercise caution with baffles too. Every "turn" the air has to make causes additional noise. If you want a high-flow system (which you'd need for high end parts), you have to make sure that air pressure is as close to equilibrium as possible with every turn, otherwise you'll be wasting your efforts.


Right on. I considered that whole "unidirectional" pressure wave concept, and realized that it's a bit more complicated with low-pressure multi-directional waves, in conjunction with airflow (which will make noise all on its own). The idea is that even if my design is restrictive to airflow (which I'll try to minimize) the baffling should cover the rest (like in the link below).

In case anyone is following only recently, check out this cool (even if a bit old) video on making a silent PC, posted earlier on in this thread: http://video.google.com/videoplay?do...8907974334180#


----------



## Slink

Quote:



Originally Posted by *Manyak*


The "large fans only" rule is bs. Achieving the same static pressure with a large fan requires larger blades and a larger motor. The larger the motor, the more vibration noise it induces.

It's about balancing the fan size with the amount of air you want to move and the amount of static pressure you need to move it.


That is an interesting point.

Unfortunately, I'm not familiar with the math behind it, but you seem to be. I'm sure there are factors such as blade surface area, blade edge area, air-on-blade friction coefficient, RPM, motor construction, etc. However, I have often swapped out smaller fans for larger ones, successfully reducing noise output while not sacrificing airflow to do so. Granted, these fans were all running on non-modified voltage (no fan controller) so I suppose the same voltage powering a larger fan resulted in lower RPM/noise? The airflow did not suffer much at all in comparison to the huge reduction in fan_motor_noise and airflow_noise.

Whatever the case, a perfect example is in this graphics card cooler mod that I did. Much larger & slower fan with similar or better airflow to original fan, larger heat sink with more surface area = increased cooling, decreased noise.


----------



## Aparition

I persued the 'make pc quieter' quest myself.

Take it with a grain of salt, but maybe it will help you out.

I have a CM Elite. Old case I got in 2006(?). Not this one but very similar, but my front panel is at the bottom. http://www.newegg.com/Product/Produc...82E16811119115

So I removed the front fan metal grill with my Dremel. Removed the Rear metal Grill as well. This removes and turbulence and so 'quiets' the fan noise from these 2 fans.

Then I bought this stuff.
http://www.pplmotorhomes.com/parts/r...quick-roof.jpg
I needed a rubber based 'something' to line the insides of the case to Deaden the case metal and hopefully absorb some sound as well. This stuff has a rubber mixture to it, is cheap (homedepot), and is thin so it will fit everywhere.

I did have success with using this as it did deaden the panels and made them heavy so eliminated any vibration from the case metal. The case fans have a smoother air sound and are more efficient. It did slightly quiet the GTX 470 Blower fan from 'hearing' it at my desk through the case. A quieter fan system is the only way to shut it up though








The case itself is very quiet compared to before with just a gentle air whooshing noise which is pleasant to my ears. The actual difference is small though from before and after. The type of air noise did change which changed how I hear it, for the better.

Now what I noticed is that the most noise was coming from the Rear of the case, and at the top front of the case where my empty drive bays are (screened by the sponge dust guard sheet). These two places had the most 'open' areas for sound to escape or the most lack of sound absorbing/dampening materials.

As an experiment I moved a case fan from the front to the Middle (inside) and removed the exhaust fan 2 inches inside. This also quieted how the case sounded.


----------



## Manyak

Quote:



Originally Posted by *Slink*


That is an interesting point.

Unfortunately, I'm not familiar with the math behind it, but you seem to be. I'm sure there are factors such as blade surface area, blade edge area, air-on-blade friction coefficient, RPM, motor construction, etc. However, I have often swapped out smaller fans for larger ones, successfully reducing noise output while not sacrificing airflow to do so. Granted, these fans were all running on non-modified voltage (no fan controller) so I suppose the same voltage powering a larger fan resulted in lower RPM/noise? The airflow did not suffer much at all in comparison to the huge reduction in fan_motor_noise and airflow_noise.

Whatever the case, a perfect example is in this graphics card cooler mod that I did. Much larger & slower fan with similar or better airflow to original fan, larger heat sink with more surface area = increased cooling, decreased noise.


The noise level of a fan is directly related to the linear velocity of the tips of the blades.

So if you have a large fan, for it to have the same linear velocity at the tips as a small fan it it would need to have a lower angular velocity (or in other words, a lower RPM). However, it is also able to move more air at this lower RPM due to the increase in blade size. And since the period of rotation is longer, the frequency of the sound it produces is lower too. And with the fan sizes used in computers, generally speaking the lower the frequency the less sensitive our ears are to it.

That is the source of your "large fan" rule.

However, since it's now moving more air, it means that the total force exerted per unit of time is also greater (or it's power, in watts). This requires a more powerful motor (and therefore, a louder motor). If the motor was kept equal to the smaller fan it would run at an even _lower_ RPM and move the same amount of air as the small fan did (assuming the blades are zero weight). But since the same volume of air is now being moved across a larger cross-sectional area (the diameter of the fan), and the velocity of the air is also reduced (since the applied force is spread out over a greater area), both the dynamic and static pressure of the airflow is reduced. This is important in PC cooling because this pressure is what forces the air to flow in between the fins of heatsinks. If the dynamic pressure is too low, the heatsink acts like a barrier, causing an area of high static pressure to be formed directly in front of it. This either reduces the overall airflow (if the fan is directly attached to it), or causes the air to be diverted around it. Either way, you end up with less effective cooling than if you had used a smaller fan that - with the same blade tip velocity - could provide a higher airflow velocity while achieving the same airflow volume.


----------



## Slink

@Aparition: thank you for the info!

@Manyak: Okey dokey. But why are 120mm fans seem so quiet compared to the 80mm fans which seem so blasted loud?!? I can't simply be due to perception of different frequencies!!


----------



## Manyak

Quote:


> Originally Posted by *Slink;13055980*
> @Aparition: thank you for the info!
> 
> @Manyak: Okey dokey. But why are 120mm fans seem so quiet compared to the 80mm fans which seem so blasted loud?!? I can't simply be due to perception of different frequencies!!


Because they need to be run faster to give you the same amount of airflow.

And there ARE 80mm fans that are extremely quiet.


----------



## Slink

Okay. thank you. I will take all of the information you have presented into account when moving forward with this. Thank you much for your input.


----------

