Isolation box for a G4

[jackruston]

Hi all
Hope everyone had a nice weekend.

Right then. I am finally going to build an isolation box for my G4 and I need a bit of advice.

I have searched on various forums and found a couple of useful posts from which I have got my design.

The idea is this....I make a box out of MDF. It will have 3 'chambers'. They go on top of each other. The bottom and top chambers are the same size and basically act as air in and air out. The middle chamber is much bigger and houses the mac itself. Air is pulled in by 2 92mm quiet fans in the base of the main chamber via the lower chamber which has an opening at the back. It is sucked through by 2 similar fans in the roof of the main chamber and allowed to escape via the top chamber which also has an opening at the back. All of it will be acoustically lined inside. I will use doors at the front and back for access. These will be simple hinged jobs with rubbber seals and foam etc. I intend to fit a padlock to both when I'm out to make the mac a bit harder to nick.

My questions.

1. What should I line it with. Is it worth using some proper foam tiles cut into bits or is that overkill? Should I just use thin foam or rubber? Rock wool? underlay? what.

2. The fans will be mounted on the 2 internal partitions, horizontally so that they move air vertically. I dont want them too close to the openings at the back in case they can be heard...So I want to put them at the front. This should be ok for the air coming in as I think the mac has an inlet at the front, but what about the back... Is it a problem to have hot air escaping from the mac at the back of the cabinet, but to have the extractor fan at the front? Should I consider using a length of duct, to make sure that all the hot air really is sucked out?

3. Will it work? While not being as elaborate as the fabled Isomac, which is just too costly, it is a fairly major undertaking for me. It will take me a whole weekend and I will have to bribe my engineering inclined brother with beer to help me. I dont want to go to a massive effort and moderate cost if instead of being the dogs bollocks, it's just bollocks.

Thanks everyone.

Jack

[Renie]

Jack!!! [img]images/icons/shocked.gif[/img]

Good luck though!!

[jackruston]

Hi Renie! How's things?

[Jordan F.]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by jackruston:
Hi all
Hope everyone had a nice weekend.

Right then. I am finally going to build an isolation box for my G4 and I need a bit of advice.

I have searched on various forums and found a couple of useful posts from which I have got my design.

The idea is this....I make a box out of MDF. It will have 3 'chambers'. They go on top of each other. The bottom and top chambers are the same size and basically act as air in and air out. The middle chamber is much bigger and houses the mac itself. Air is pulled in by 2 92mm quiet fans in the base of the main chamber via the lower chamber which has an opening at the back. It is sucked through by 2 similar fans in the roof of the main chamber and allowed to escape via the top chamber which also has an opening at the back. All of it will be acoustically lined inside. I will use doors at the front and back for access. These will be simple hinged jobs with rubbber seals and foam etc. I intend to fit a padlock to both when I'm out to make the mac a bit harder to nick.

My questions.

1. What should I line it with. Is it worth using some proper foam tiles cut into bits or is that overkill? Should I just use thin foam or rubber? Rock wool? underlay? what.

2. The fans will be mounted on the 2 internal partitions, horizontally so that they move air vertically. I dont want them too close to the openings at the back in case they can be heard...So I want to put them at the front. This should be ok for the air coming in as I think the mac has an inlet at the front, but what about the back... Is it a problem to have hot air escaping from the mac at the back of the cabinet, but to have the extractor fan at the front? Should I consider using a length of duct, to make sure that all the hot air really is sucked out?

3. Will it work? While not being as elaborate as the fabled Isomac, which is just too costly, it is a fairly major undertaking for me. It will take me a whole weekend and I will have to bribe my engineering inclined brother with beer to help me. I dont want to go to a massive effort and moderate cost if instead of being the dogs bollocks, it's just bollocks.

Thanks everyone.

Jack<HR></BLOCKQUOTE>

You might do well to pick up some Super Absorbent padding/mats from www.soundproofing.org. Maybe stack a few of them together.

Jordan

[Barnabas]

Sounds like a good plan. I assume you've seen my info at www.barnabas.com/sound

I think you can skip the two fans at the bottom. They are probably redundant. Also it is usually better to pull air through a box than to push it through. If the top fans and the bottom fans are not perfectly matched for air flow, then you might create a high pressure zone in the box. This might be cool for weather experiments, but it will try to push your door open. With just a top fan, the low pressure in the box will pull the doors closed. If you have 12V DC fans, you can safely run them at a lower voltage to reduce the noise. My box has a single 12 VDC fan running at 9 VDC.

If you can have the air coming in one side of your box and out the other side, you should be able to have the air coming in the front of the Mac and have the upper fan behind the Mac to suck the air out. I have the air coming in and going out the same side of the cabinet. This makes it possible to recirculate the hot air into the system again, which is not desired. If the G4 is not too tight in the main chamber, then it shouldn't matter where the fan is located as long as you allow the hot air to naturally move up.

I wouldn't put any foam padding in the box. Foam tiles keep the sound from bouncing off of the walls but do nothing to keep the sound from going through the walls. To keep sound from going through walls you need mass. This means sheetrock, or thick MDF. I saw someone advertise a rubber sheet that was supposed to keep sound from going through. However, you might put a foam pad under the G4 to reduce vibrations from the computer reaching the floor.

If I had to do it again, I'd use two layers of 3/4" MDF or maybe one layer of MDF on the outside and sheetrock on the inside. My hard drive sometimes burps really loud when it records.

Good luck. Post some pictures somewhere.

[jackruston]

Thanks Barnabas. I have indeed seen your link, and found both inspiring and very useful.
Jack

[KamaSutra77]

I built my box just large enough to hold the mac, the top come off and theres just a hole at the bottom for cords. Works pretty well, the trick is to allow enough internal room for the fan to circulate the air - within the box. it doesnt seem to get to hot or anything. Pretty quiet but not noiseless. I think the fans and absorbant materials are a bit of overkill. Ive been meaning to get the thermo coupler for my multimeter so I can confrim that the operating temperatures are not getting to high, but I havnt yet. Didnt see the need I guess,i open the top put my hand in and go ok, a little warm but not hot. And go back to work.

[Renie]

Hey Jack, things are good thanks!

I'll drop an e-mail to you soon and in the meantime I'll let you all get back to G4 box building!

Renie
[img]images/icons/smile.gif[/img]

[Michael Klinger]

This is not a criticism, simply a matter of curiousity. I know that everyone's situation is quite different, and I admire the lengths and effort that some people have gone through to think about, design, and build enclosures to keep their rigs quiet. But given the amount of mental energy, time, costs of materials, etc. I would love to hear opinions about how this compares to (as an alternative) remoting the noisy components to another room, through the use of extenders from Gefen or less expensive exender solutions. The solutions become particularly affordable if your remoting run is short (such as through an adjacent wall). I have seen the ISOBOX, and I have seen the Barnabas Pictures (although peeking at them made me feel dirty). ISOBOX seems so bulky. It takes up a huge amount of space.

-Mike

[KamaSutra77]

My design is so simple its funny LOL Those geffen boxes and extender kits are way to expensive.