O/T: Help Wanted With Quieting Down a Projector

[shane2943]

Hi everyone. Hope your 2011 is off to a good start.

So, I have a BracoGraphics 4000 projector (info here: http://www.projectorcentral.com/Barco-B ... s_4000.htm) that I'm currently using for my HT. It's not ideal for HT but I got it free (not stolen), built a 108" screen for 100 bucks and have been using it for the past 6 months or so. Works well enough.

It's currently sitting on a shelf that is hung from the ceiling about 7ft off the floor (11ft ceiling). Right now, it's literally about as loud as the average microwave.

I found a couple hushbox designs and thought I'd try my hand at one. Please critique my design. I'd rather build once and have it be right.

Here's a front shot of the enclosure:


Here it is in X-ray vision so you can see the baffles and air channels:


And here's a top shot:


The intake for the projector is under the lens and the exhaust is on the left side towards the back (in the picture of the projector at the link above, you can see the exhaust vents). The fans on the enclosure are 3 120mm computer fans run at 1/2 speed. I want to line the hushbox with damping material that will further absorb noise from it and keep it inside the box. The window at the front will have glass (anti-reflective) installed.

What do y'all think? Sorry it's off topic. When I get my BFM HT built, I won't be able to hear the projector anyway, hushbox or not (or the microwave, or the vacuum, or a tornado, or the cops knocking....)!

[SoundInMotionDJ]

In general, for cooling you are better off with fans blowing air INTO a case, rather than sucking air OUT of a case.

I would keep much the same design, but move the three "exhaust" fans to the right side (looking from the front) of the case, and direct them to blow air into the case. These could be near the back of the box where you have the rectangular air inlet. I would also cover the fans with some kind of lined grill to cut down on the amount of dust that gets sucked into the projector.

Using a little foam gasket tape, you can "seal" the intake side of the projector from the exhaust side. That will go a long way toward keeping the air moving in the right pattern.

--Stan Graves

[shane2943]

Sweet. I'll see if I can modify the design to move the fans over to the intake side.

Thank you for your insight!

[shane2943]

Mkay, fans moved to the intake side. This actually allowed me to move the angled baffle on the exhaust side over more away from the projector for more space:



More opinions welcome!

[subharmonic]

When mounting fans in the past on cabinets there became issues of noise from the fan itself vibrating against the cabinet or moving the cabinet itself.

The solution we always used was to drive screws in about 1" from each mounting point on the fan and use zip ties to the mounting hole and the screw. Worked like a charm every time, however they were all vertical mounted fans so that make be harder in this situation. They came out with a rubber surround but the zip tie method worked the best.

Also you may consider a area for a air filter, like the ones on cat litter boxes to keep some of the larger dust off the projector.

These are the fans we used.
http://www.activethermal.com/

Or you could Tim Allen Tool Time it and build a elaborate system to push and pull air from the adjacent room with a whole bunch of ducting, completely isolate the projo from your room.

[shane2943]

When mounting fans in the past on cabinets there became issues of noise from the fan itself vibrating against the cabinet or moving the cabinet itself.

The solution we always used was to drive screws in about 1" from each mounting point on the fan and use zip ties to the mounting hole and the screw. Worked like a charm every time, however they were all vertical mounted fans so that make be harder in this situation. They came out with a rubber surround but the zip tie method worked the best.

Also you may consider a area for a air filter, like the ones on cat litter boxes to keep some of the larger dust off the projector.

These are the fans we used.
http://www.activethermal.com/

We have these rubber nipple looking things at work that "pull" in the holes on the fan and then "pull" into the holes where the fan is mounting. The rubber isolates the fan from the housing completely. Was probably going to use those. I hear ya on the ziptie method and have seen similar things done with success.

Or you could Tim Allen Tool Time it and build a elaborate system to push and pull air from the adjacent room with a whole bunch of ducting, completely isolate the projo from your room.

LMAO! You know, as loud as this jet engine is, I might consider that!

[DanielNY]

Since this case is more or less the size of a computer case, I would suggest buying Quiet PC fans. The fans run about 30-40 bucks a pop so may not be the cheapest solution.

The other solution is building a new case with all fans mounted internally with a few more channels between the outside and inside. The more bends and damping, the less noise travels. This is the same concept studios use to keep A/C air ducts quiet. The channels are lined with some kind of damping.

[shane2943]

The other solution is building a new case with all fans mounted internally with a few more channels between the outside and inside. The more bends and damping, the less noise travels. This is the same concept studios use to keep A/C air ducts quiet. The channels are lined with some kind of damping.

You know, it's funny you mention that. The design I posted at the top of this thread is actually the 4th redesign. Here are the first 3:

1:


2:


3:


Unfortunately, I'm limited by external size of the box. This thing will have to hang from the ceiling above the couch in the livingroom. The WAF is already not looking forward to a bigger thing hanging there than the projector/shelf already is. My previous 3 designs have pretty tight channels and don't really leave room for damping material. I can probably go larger vertically, but not depth or width (shoot, the design is already 28" wide). Tryin to find the best compromise, you know?

But, if you see a way that I didn't to organize the channels, maybe with a little bit higher ceiling in the enclosure, please, let me know! I'm definitely no engineer.

Thank you for sharing your thoughts and knowledge, DanielNY! I really appreciate everyone's help on this.

[DanielNY]

Nice work!

I think it's a toss up between design 1&3. In every design you have the fans all on one side which may be asking too much of them and wont bring in enough cool air. If you have two pulling in cool air from one side(preferably as parallel to the bulb as possible), and another 2 for exhaust would work better. Also, the channels dont have to be the same thickness as the outter shell, all you need is 1/4 material with a thick cloth like speaker cabinet covering to line the channels.

Just my two cents...

[shane2943]

Nice work!

I think it's a toss up between design 1&3. In every design you have the fans all on one side which may be asking too much of them and wont bring in enough cool air. If you have two pulling in cool air from one side(preferably as parallel to the bulb as possible), and another 2 for exhaust would work better. Also, the channels dont have to be the same thickness as the outter shell, all you need is 1/4 material with a thick cloth like speaker cabinet covering to line the channels.

Just my two cents...

Hmm...definitely food for thought. So instead of simpler wider channels and thicker damping material (V4), you're recommending longer more complicated channels with bends and folds and very thin damping material right (like V1, 2, and 3)?

I can pick up a 4th fan, no problem. I just hope that 2 fans bringing in the air will be enough. Might have to run them at a higher speed. This projector really does pump serious air through it. It has 5 fans inside it! O_O I'm not kidding. It's no wonder it's as loud as a microwave.

Question: if the interior of the box is sealed, would it make a difference whether or not there are fans at both the intake and exhaust? I'm askin because I really don't know. Physics wasn't my strongest subject.

Gonna have to go back and explore the first and third designs.

Thank you, sir!

[DanielNY]

I'm sure the projector has the same config with some fans taking in cool air and another setup for exhaust. Same concept with PC's so if possible position the fans so they complement the air flow of the projector making it as efficient as possible.

Thought of your last comment about long channels, as long as the fans are not directly on the outside of the box with at least one channel seprating them from the actual exhaust port and also keeping the channels wide enough so that there isnt a direct path from fan to exhaust which it seems like on the right side of drawing 3, everything else looks good and I would keep as high a ceiling inside as possible.

I dunno if this was mentioned already but what size fans are you using? the bigger the fan, the slower it needs to spin to keep things cool and thus less noisy. This is why I suggested PC cooling fans as big as you can go. I rely on fans by Noctua to keep things quiet on my studio PC's.

[BoostFab]

the projector put out a lot of heat in a short period of time, to properly cool it to prolong the lamp, you have to draw the hot air fast. from the look of your design, the heat may not draw out properly. since heat rise to the top, I think it's better if you have the fans at the top, and the vent tunnels on left and right stay clear to draw in fresh air. think of it like the AC outside unit. Using 100mm ball bearing quiet fan will keep things silent.

[shane2943]

I'm sure the projector has the same config with some fans taking in cool air and another setup for exhaust. Same concept with PC's so if possible position the fans so they complement the air flow of the projector making it as efficient as possible.

Thought of your last comment about long channels, as long as the fans are not directly on the outside of the box with at least one channel seprating them from the actual exhaust port and also keeping the channels wide enough so that there isnt a direct path from fan to exhaust which it seems like on the right side of drawing 3, everything else looks good and I would keep as high a ceiling inside as possible.

I dunno if this was mentioned already but what size fans are you using? the bigger the fan, the slower it needs to spin to keep things cool and thus less noisy. This is why I suggested PC cooling fans as big as you can go. I rely on fans by Noctua to keep things quiet on my studio PC's.

You know, you're right. The projector itself does have intake and exhaust fans (and a couple more to direct air inside it). So adding another fan and having 2 push in and 2 pull out looks like it'd be a good idea.

The fans are 12V 120mm computer fans so not the biggest, but not 80mm howlers either. when they're running at 1/2 speed (6V) they are very very quiet. Hopefully I can continue to run them at 1/2 speed but if not, having them burried in the box should help.

I am positive I cannot widen the box any, but I might be able to add a couple inches of depth and height to it with height being the most flexable dimension currently. I'll raise the height a couple inches and see what I can come up with as kind of a hybrid between designs 1 and 3.

I have a bunch of automotive carpet padding in my attic and egg crate foam. The auto carpet padding is about 1/4 - 3/8" thick. Would you recommend using that to line the channels to keep reflections down?

Thanks again, Daniel!

the projector put out a lot of heat in a short period of time, to properly cool it to prolong the lamp, you have to draw the air fast. from the look of your design, the fan could be better on the out side edge of the left side, to draw air out through the tunnel. optionally, you could add a second set of fans on the right to push fresh air in. Using 100mm ball bearing quiet fan will keep things silent.

I know without a doubt that 3 of these 120mm fans I got will move more air than the projector does running at 1/2 speed. Not sure about 2 fans though (at least at 1/2 speed). What I can try and do is raise the box ceiling and bury 2 intake fans and 2 exhaust fans inside the box with at least one baffel between them and the inlet/outlet ports. At least that way, if 2 fans don't move enough air at 1/2 speed, I can speed them up while keeping things quiet.

Thank you.

[BoostFab]

120mm is even better.

this is what i would do.

[shane2943]

That would yield one mega huge box unfortunately. Which sucks because that looks like a good design.

Well, here is the best I can do. 4 fans (two intake, two exhaust), all 4 buried inside the enclosure, all 4 fans behind baffles, enough room for sufficient airflow, and top venting (this was the hardest part):




Top view with top piece removed:


Side view (exhaust side) with side piece removed:


I heightened the box by 2.5 inches (total inner height is now 9.5") to allow enough room to stack the fans. Wish I could go wider, but 28" OD is as big as I can get. I also reduced the inner walls to 1/4" pieces instead of the previous 1/2" pieces.

What do y'all think? I think this is the best one yet and a real candidate for the actual build.

Thank y'all so much again for taking the time to help me with this.