My DIY Isolation Box design

Posted: Sat Oct 04, 2008 9:26 am

I've been working on this ISO box design for a while now, and this is the latest. I'm posting it to get some feedback before I start construction on it.

Some details:

-Yellow is suppose to be glassfiber absorbers (covered with fabric). Orange is suppose to be rubber seal. Red text is for ISO box measurements. Blue text is for computer/external drive measurements.

-The cords and cables will be going through foam with slits (the dark grey part)

-The fans are 120mm fans, ideally with temperature sensor and variable speed. (But I don't know if those features only work when they are attached to a computer).

-The fan funnels are made to not be straight on purpose, so the airflow can be quieter when exiting.

-I'm not sure what locking devices to use on the doors yet. Maybe a simple sliding one like those on public bathrooms--as long as there's some tension (from the rubber seal) to keep the lock in place.

Posted: Sat Oct 04, 2008 12:11 pm

Are there 6 fans? That would be noisy no mater how the air is flowing. Can you make a machine room? Do you have an adjacent room you can put the computer in, and run the cables through the wall?

Posted: Sat Oct 04, 2008 9:24 pm

I have no option for machine room. Adjacent room would be the bathroom. I have a storage closet a the other end of the room, but I'm not crazy about the idea of running really long extension for USB, VGA, RCA, 1/4"...etc cables, and it's a much longer trip every time I need to put in a CD or a DVD or turn on or off an external hard drive.

If the noise is more than I expected, maybe I can design another absorber that faces the intake and exhaust holes (but with maybe a 2~3 inch gap so air can still move) so that as the noise exists the holes, they'll run up against the additional absorber. Would that help?

Posted: Sun Oct 05, 2008 12:46 am

Lunatique wrote:

I'm not crazy about the idea of running really long extension for USB, VGA, RCA, 1/4"...etc cables,

I think the spec is like 16' for USB any way. I'm using 16' active USB cables with no problem. If you need to go further than that then they probably wont work.

Posted: Sun Oct 05, 2008 5:22 am

It looks really nice and you've obviously put a lot of effort into this but I gotta tell you, unless your pc is REALLY loud, I cant imagine needing it. I have two pcs going in the room with my mics and I dont really suffer any because of it. I do have booths for vocals and amps but I have also recorded alot of acoustic guitar right out in the room and had no problems. Technique might be your best solution. My pc's are in my desk and therefore only open to the room on the front and back. I have some loose sonoflats from auralex and I just lean them in front of the pcs when recording. I also use cardiod pattern mics and usually up close on the source. You can check out the pics of my room at www.myspace.com/composerwatkins. Hope this helps.

E

Posted: Sun Oct 05, 2008 5:30 am

I must be dense - I do not see a logical flow of air feeding the front of the computers - and exiting off the back of the machines

Perhaps a simple section through the side of the box detailing the air flow would help me get it

Rod

Posted: Sun Oct 05, 2008 6:50 am

Rod Gervais wrote:

I must be dense - I do not see a logical flow of air feeding the front of the computers - and exiting off the back of the machines

Perhaps a simple section through the side of the box detailing the air flow would help me get it

Rod

The second image shows it (but you need to paste the URL into the browser since it's not showing up in this thread for some reason).

EDIT: I changed the name of the file and it now shows up.

Basically the bottom fans will suck air in through the bottom air intakes. The computers will suck in the cooler air on the bottom of the room, and the computer's back exhausts will blow out the hot air, then the upper fans will blow the hot air out of the upper exhausts.

Posted: Sun Oct 05, 2008 6:51 am

It is so over engineered it should be used as an example of what not to do.

Build an airtight box. Cut two holes in this box on opposite sides and pump air into one of them, have the other as an exhaust. You can suck air through or blow it. Use ducting to move the air to and from the place where you want the box to be. Have the fan outside next to the HVAC. You don't need a massive fan, or six, just one household exhaust fan should do.

Posted: Sun Oct 05, 2008 6:56 am

It looks like the air intake is at the bottom rear and the exhaust is at the top front.

Posted: Sun Oct 05, 2008 7:02 am

Greener wrote:

It is so over engineered it should be used as an example of what not to do.

Build an airtight box. Cut two holes in this box on opposite sides and pump air into one of them, have the other as an exhaust. You can suck air through or blow it. Use ducting to move the air to and from the place where you want the box to be. Have the fan outside next to the HVAC. You don't need a massive fan, or six, just one household exhaust fan should do.

This is definitely a bit more complex than my earlier design--mostly because I wanted to be able to open the box from all 4 sides. I did consider your idea originally but I'm not confident a normal household fan would be quiet enough, especially when one end of it is shoved into a duct.

Posted: Sun Oct 05, 2008 7:28 am

Put the fan outside. Run a duct inside.

Posted: Sun Oct 05, 2008 8:08 am

Greener wrote:

Put the fan outside. Run a duct inside.

I suppose I could put a household fan inside the storage closet, then run a duct out into the studio and into the ISO box. I could try that if my design doesn't work out.

Posted: Sun Oct 05, 2008 8:20 am

I would build a quiet computer OR get a rack mount purposed machine.

Posted: Sun Oct 05, 2008 8:43 am

The box does NOT look to be that much over engineered... a tad excessive fan-wise... maybe, but not grossly so.

As I suggested in your original post, the thermal dynamics of air flow (Rod's Baileywick) are paramount... either by having an internal negative pressure, or a 1:1 pressure that is moving air through the computers at the same rate as the internal PSU fans. (Negative pressure)

Your internal air pressure needs to be such that it is actually working with the fans inside the cases of the computers. Most fans are designed to move the heat from the power supply out of the box... drawing air in by creating a negative pressure and pulling in cool air from the bottom of the case.

The typical CPU fans blowing directly down on the processor would seem to be creating a counter vortex of air column inside the enclosure by creating a positive air pressure zone around the CPU.

How that relates to the volume of air column movement, I'm not 100% sure, but I know it is addressed by the better manufacturers.

My guess is that to do this right, you would need to read what the volume of air rating is on your PSU's (cfm). Then, take into account the BTU's generated by the additional items in the enclosure. In my basic understanding of it all, you add the volume of air column in the enclosure and factor in the velocity of your existing air flow to establish the required air flow. What I am not sure of is whether the process is purely additive or if there is some factor that comes into play.

I'm not versed enough in air flow to say that your fan design would indeed be a problem. I'm just somewhat suspicious that your air flow rate may not be adequately calculated and hope that Rod will clarify.

[ edit ]The goal you are looking for is to move the greatest amount of air that you need to, at the slowest velocity you can achieve. That will result in the desired result of not hearing your fans. [ /edit ]

Posted: Sun Oct 05, 2008 9:22 am

Yer right it isn't over engineered. The fun part is when this thing is complete and gets turned on, hear that sucking sound? Or is that a blowing sound? Must be the doors...

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