Crtique My Projector Hushbox (before I start building)

Hi everyone.

I hope this is the right section for this. My theater is my living room and my projector hangs about 3-4ft from the ceiling (high ceiling). Can't mount it higher or lower due to the projector not having any sort of keystone adjustment.

The projector has 5 fans in it and sounds like a jet engine mounted to a freight train. I read some other threads on hushbox design and tried my hand at my own design. This design is somewhat "universal" in that when the bulbs (yes, bulbS...this projector has two) eventually go out, I'll just buy a new projector instead of replace the bulbs and I want the new one to work in the same hushbox.

Here's some sketchup drawings of the design I came up with:




The air will be pulled into the right channel and exit the left side of the box since the rear left side of the project is where it's exhaust is.


The air channels will be lined with a sound damping material. The fans are 120mm computer fans and will have a trim pot to adjust the speed of them. The overall dimensions of the box are pretty large but the projector itself isn't small to begin with.

Thanks in advance!

Thanks for the input, guys!

The opening in the front will be sealed. Two layers of either glass or plexi-glass to form a window.

I can expand the projector's chamber so it's a bit larger. Can't go too much larger though because the box is already pretty big.

The projector is a BarcoGraphics 4000 and is hella noisy. I doubt quieter fans could be installed in it. It seriously has 5 fans. This projector was given to me for free so I might as well make use of it.

The damping material I was planning to use is about 1/4" to 1/2" thick (automotive carpet padding). Not as effective as the 1" material by any means, but that's why I opted for the bends and turns in the channels. The bends by themselves should offer some harmonic damping. Kind of like how a horn or transmission line subwoofer's folds cancel out 3rd order harmonics. Unless I'm wrong, of course.

The whole box will be sealed air tight except for where I want the air to flow, so, in my mind, it doesn't really matter where the fans are. With the fans "pushing" the hot air out, the air will only have one place to go anyway due to positive pressure created by the sealed box. I can easily move the fans to the exhaust side though in the design if I'm wrong here too.

Far as the different models of projectors going in this box, I'm not too worried. The projector is large, which means any model of projector I buy after this one goes will be smaller (most likely significantly smaller) and will also generate less heat (this one has 5 fans for a reason). I figure that the air flow in this box should be enough to move the heat out no matter where the exhaust is located on the replacement projector...again...unless I'm wrong.

Thanks again for taking the time, gentlemen.

Ok, I moved the fans to the exhaust side and modified the intake side for more sound blocking:



I also included dimensions in this drawing so y'all can see the outer size of it.

Hmm...good point.

Gonna check that out in the model.

Thanks!

Yikes! I'm glad you chimed in!

What if the window was at an angle to the lens?

I'm guessing this is why most of the designs I see use the "port hole" approach.

Ok, taking into account the need for larger channels and that glass cannot be parallel to the lens, here's V3.0:

The channel openings are now on the top instead of the sides:


This view shows the larger channels:


This view shows the glass frame being angled to the lens:


Also got the fans today. They are 12V computer fans and they move a TON of air! Way more than the projector moves. So I decided to run them off of 5V instead of 12V and that seems to be the perfect speed. They still move tons of air, but they are much quieter.

Thank y'all for the help so far! It's much easier to fix design flaws in Sketchup than after the sawdust has flown.

Ok, just did an experiment. While the projector was on, I held a piece of glass (from a picture frame) in front of the lens. I held it both parallel and at an angle. I could tell a slight difference in picture but it only looked a slightly darker from when the glass is not in front of it. There was no noticeable difference between the glass being held parallel and at an angle to the picture. The glass does reflect quite a bit of light from the lens so an angle would be best.

Unless there's something I'm missing (like damage to the projector or something), it seems plain glass will work ok. Not perfect, but well enough.

Nope. The image looked just as sharp and clear, just a little bit darker.

I'm going to try the test again with different images on the screen to be sure. Last night's test was just a quickie.

My apologies to give off the impression that I'm arguing. I'm not at all and I'm definitely listening and thinking about everyone's suggestions. $40 is not as bad as I thought it would be. I was picturing it to be much more expensive which was why I tried the experiment to see if regular glass would really be "that bad."

You say my design is over engineered and flawed, please, give me your suggestions! This is definitely a budget centered project but perhaps there are other ways of doing things that won't break the budget.

Again, I'm sorry that I gave the impressions that I'm not listening or taking into account all that members have said because I most certainly am!

How would you orient the fans to the course of the channel? I think I'm understanding what you're sying here, but am trying to picture it in my brain. The way the fans are now, the exhaust from the projector blows right at the fans. I am totally open to moving them though if they're not in a good position.

Filtration is a very good point. My house is not necessarily all that dusty but no dust at all is best. What would you recommend for filtration?

Thank you for taking the time and for your suggestions.

Also, just to help clarify, the intake on this projector is on the bottom (squirl cage fan) of the unit in the front corner where the lens is (the mockup of the projector in the Sketchup is pretty accurate). The exhaust is on the left side of the projector towards the back (where the hushbox fans are currently). Hope that helps. Should have stated that way earlier.

Also, I'm beginning to see where creating a "universal" hushbox is a bad idea. I can at least build this one without glue so I can at least take it apart and reuse the wood for the next hushbox.

Thank you for your insight and for the information about the glass! Describe the elaborate circulation system if you can, please.

Temperature probe is a great idea. I have one that came with my multi-meter.

Ok, upon the recommendations of many here, I have simplified the box a bunch. Widening the channels to accept more air flow and thicker damping material. With this design, the damping material can be thicker and be the densest most sound absorbing material I can find. Also, the fans are now on the exterior (top) of the box and the window on the front (again, from recommendations) has been made much much smaller.

Putting the fans on the outside of the box was a small concern for me, but I ran all 3 at the same time at 1/2 speed (5V instead of 12V) and they are very quiet at that speed. Not to mention, the fans will be aimed at the ceiling and the box will be suspended about 7ft off the ground.



Here's a view inside to see the simplified and expanded channels:


There will have to be a 2nd smaller window on the front so the remote will work with the IR pickup on the front of the projector. I could use one of those IR extender dealies, but, again, money.

I will use an anti-reflective glass.

What do y'all think?

No takers?