i have read through the posts that have come before, however i would like you advise on some of the options i have found.
i have a cheap Aluminium case that is very thin. it does very little to deaden any noise. I know most of the noise will be escaping trough the back, but i have several strategies for that.
it occured t me that there must be several cheaper alternatives than the special composite materails being flogged. i have read the suggestion f the sound damping ceiling tiles from home depot type places, however i dont thing they will have enough density to bulk up my case. therefore i was considering MDF, if i were to silicon a half inch thickish piece, to the side panels,ceiling, floor etc. then woudl this stop the sides resonating and deaden a lot of the escaping noise?
the other cheap option that occured to me was plaster board the stuff used to make partition walls. again i could attach soem to the exposed areas inside to bulk them up.
another material i considewred is the 'printing rubber' detailed in the article on encasing you hard disk in rubber.
i could then (if you think it may help, glue some high density thin foam to the surface of either of these to actually damp the surface and stop reflections.
i am fairly sure that most of the escaping noise it coming straight from the sides at present so i would think this would, at least, make the rear vent the biggest noise source.

i'd very much apreciate any input on this, as id rather not trial and error if people have already done it. or if theres another solution please let me know.
many thanks

To get the density up you want to use some roofing tape from homebase or B&Q. It is a bitumen based layer with an aluminium layer on one side - about 2mm altogther. You warm the bitumen with a hair dryer and stick it straight to the inside of the case. Then duct tape along each edge to double check it wont come off. It is much more dense than mdf/plasterboard, flexible so it will stick properly to the case, and is self adhesive. Dont worry , it doesnt smell either You could also use two layers, which i did, to really add weight to your case. It comes in loads of sizes (upto about 25cm wide), and i bought 25cm x 10m for £15 as i was using it in my car too - jus to give you an idea of cost/area.

You could then put thin foam over this dense base to absorb the higher frequency sound. Mouse mat type thickness/density is perfect. Or you could use foam carpet underlay, as i did.

thanks a lot, i did read through your post about the carpet underlay and the like, however it seemed to me that wood would be a better sound absorber (i based this on nothing other than that was what my brain said) hence if this bitumen based tape will do the job i shall head down to wickes as soon as i get a chance.

thanks a lot.

ps the heat in the case wont case this stuff to sag and peel will it?

Yeah, as soon as you pick the stuff up you will realise its perfect for the job, very dense, flexible and self adhesive. It shouldnt sag or anything, but while your there get some duct tape (2" wide stuff) so you can tape around each edge of the roofing tape as you put it on.

The stuff in my car isnt taped around the edges and it has been fine, and im sure my car gets much hotter than my computer case in the summer... even in england!

i have just come back from a trip to my local hardware stores. wickes and a little local shop. i had a look at the roofing tapes. basically i wasn't sure it was the stuff you meant, as it was very thin, less that 1mm and not nearly as heavy as i had imagined. i was thinking it would be a good 2mm thick and weight a ton. is this the right stuff? it doesn't seem the like the the best thing for sound proofing and i would be more convinced of 1cm thick mdf.
please let me know if this is the right stuff or if i need to get off to b&q or homebase.

cheers
ps if the stuff in wickes is correct then its a lot cheaper than the price you quoted at b&q, more like £5-7 for the amounts you said. (i think thats right anyway)

Found a pic here of something which is like what i meant, you will need to use a couple of layers.



Its what people use to dampen vibrations in cars too.

ps: how were you planning on attaching the mdf to the case? You said silicon, but did you mean over the entire panel? Cos the whole panel needs to be attached to the mdf to stop the panel vibrating.

thanmks, it was the right stuff i found in wickes. like i say i just thought it would be thicker. i shall buy some of the really wide stuff and put a couple of layers on. it certainly cant hurt. (uless i hapen to change the resonant freqency of th case to exactly that provided by the fans, now that would be unlucky)

cheers.

Hello:

Relatively new at posting, but I have been following different forums for months and experimenting at the same time.
Currently I am using sheet cork to line my case; cut to size, sprayed with contact adhesive, then attached.

It has cut down vibration via my generic case considerably. Other mods have helped including de-coupled case fans, modified CPU cooler, PSu mods etc.

I was recommended bitumen as a mass loading material and thus reduce vibration in the case. Some of the computer specific sold sound absorption/sound reducing material like magic fleece. Proudly states that it does not contain bitumen due to health issues.

Anyone know if there any health hazard in lining the computer with bitumen? Any URL to recommend (did some Google never found anything useful)?

http://www.concawe.be/Html/REPORT1-97/B/B43.htm

Doesn't seem like it is much of a health hazard. Most references are to burns or vapors from when it is super hot. It's basically tar. I used to work with bitumenous felt when building speaker cabinets. A thick piece about 40-60% of the size of a panel slapped on with more tar-goop "glue", then held down with pressure till dry. Warnings about making sure this is done in a welll-ventilated place, to to make sure it has stopped smelling before sealing the box up (could break down bextrene speaker cones). It dampens panel vibration & adds mass to reduce noise transmission.

Lots of different materials can be used to do this -- including medite board, particle board, etc. The key is to bond it tightly over the entire surface of the material to the case panel. Without the tight & continuous bonding, it is not nearly as effective, especially as the air gaps between will actually vibrate.

OK, thanks I'll go with bitumen then (easily accessible). I'll just make sure I have enough cooling so that the case don't reach the burning point.

[quote="Raygun"]OK, thanks I'll go with bitumen then (easily accessible). I'll just make sure I have enough cooling so that the case don't reach the burning point. [/quote]

This may be to late! Found some interesting closed-cell material at Home Depot. Roughly 2' X 2'; puzzle-type edges. Easily cut with scissors or a box knife. Look at their flooring department - comes in a 4 - pack for $19.95 Cdn.

Yes, I have lined the case with bitumen, works to some extent for the vibration. Not entirely when all my drives spin up (4 of them incl. WD, IBM, Maxtor and Seagate), even with them in the built in grommets of the SLK3700 case, they can cause some irritating vibration in the lined case. It does go away if I suspend the entire case on foam, doesn't look to good though. I suspect the WD and the IBM drives. Might suspend them better.

It’s really hard to tell if it has any effect on high pitch noise, since most of it comes out of the back of the case. The foam might have some effect either with another layer of lining and/or behind the case for the high pitch?

Since we do not have home depot in Europe or at least not in Sweden I would be interested in the maker of the foam. Maybe I could track down another reseller here.

The foam panels ahrbruz mentions are also available at Sam's Club....$8.
Like he says these are easy to cut and can be used in many applications. That pack of four will last through many mods!

The product name is Sof-Styles Foam Mat, manufactured by Cha Yau Sponge Enterprise Co. Ltd., based in Taiwan.

Thanks, I'll see if I can track them down here.