Here's how to quiet the Lt150: Get hold of a D-ILA projector and use it for a couple of weeks. After that just about any other projector will seem silent to you. I have had a G15 for a year and a half and I got one of the Lt150's for a vacation place. I have trouble believing that people complain about the noise from this little devil. All in one's expectation, I guess. Art
Here's an experiment. The LT150 draws about 150 watts. Build your box, and put a 150W light and a thermometer in it. Look at the thermometer after, say, 15 minutes. http://www.avsforum.com/ubb/eek.gif
Assuming worst case conditions (200W) I computed I'd need 64 CFM air flow to keep the temperature rise under 10F.
Edmund Optics offers nice, low reflection windows: Here
Get hold of a D-ILA projector and use it for a couple of weeks. After that just about any other projector will seem silent to you.
Your idea is okay except the part about no ventilation (as REF pointed out). A great many projector owners build what's come to be known around here as a "hush box". It's usually in the form of a square enclosure constructed of clear acrylic panels. Has a ventilation system using quiet fans. Try doing a forum search for "hush box" to learn more about what others have done.
But it just seems to be too much of a hassle to silence the LT150 (the whisperflow looks nice, but $400, well...). I wish it was simple as it is to silent a computer ( www.cnssystem.com ). I'll just have to wait and hope that in the next 6 months some new pj will arrive, which will give the same value as the LT150, with less noise.
The piano could have been it (32db noise), but 450 lumens, and only 800x600 res', what a shame.
I made a hush out of IR transparent Acrylic. It is black when you look at it but Ir goes right in.
The next design imployed sonex too. made the system much quiter. fans were a pain to find. I finally found 2 that I could live with. I can tll you this. 55CFM kept the temp in the box constant. The Sonex that is 3 inches away fromthe exaust of the LT150 was cool to the touch after 2 movies in a row.
I used 2 inch styrofoam!! When facing the projector, I cut a 6" x 2" hole on the left side -BOTTOM- (For air intake) and on the right side I put a 4 inch fan -TOP- (Fans designed to blowout hot air) on a dimmer to control speed, with a 3 foot long 4" x 4" duct. (After the hushbox's inclusure)
It is extremely quiet! The temperature in the box is consistently around 2-6 degrees higher than the outside temperature (Room of course). I have a infrared heatgun!
The only reason I used Styrofoam is:
2. Extremely lightweight.
3. Extremely easy to manipulate
4. So easy to work with
Tools needed...utility knife and some screws.
This whole project cost me around $20.00 excluding fan.
Trust me it is very sturdy!
Just sharing what I did and hope it gives you some ideas.
I built a hushbox from 3/4" MDF for a NEC VT540, and I'm pretty sure you could do the same for an LT150. Since I painted the thing flat black and the projector is dark gray, I have not been able to successfully photograph this unit. But let me describe how you go about it.
The projector is located on top of an 84" high bookcase that spans the rear of the living room, and projects on a screen on the front wall. Books make excellant sound diffusers! My hushbox/dustbox has plastic padded feet on the bottom, but you could also use a similar box at the end of the ceiling mount pipe. The dimensions are approximately 10X12X13", and I was trying for as small as possible to minimize visual impact.
MDF is a great choice because it is cheap, works easily with common woodworking tools and fasteners and glue, and damps sound exceptionally well. Which is rationalization - I used it because I had some left over from constructing my five MTM home theater speakers. Plywood would also be a good choice although more expensive, and particle board would be a little cheaper and harder to work with, but could also be used.
I purchased a standard Chief brand ceiling mount for the VT540, and suspended the projector inside by bolting the mount to the top of the box. There is approximately 3/8" clearance on the left and rear of the projector as you look at the front of the unit - I made sure there were no air intakes on these sides. The 3/8" clearance allows the limited use of the adjustment features on the mount, and the gap was filled with 3/8"X3/8" adhesive closed-cell weatherstriping, after aiming. On the right side of the box is a 3" wide horizontal MDF partition, and this and the weatherstripping zone the box into a cold air chamber (below, containing both air intakes) and a warm air chamber (above, where is located the single exhaust vent on the inverted projector). The 3" space on the right is used for video cable routing, two muffin fans, and a HEPA filter (it is a common inexpensive Eureka vacuum filter, 4X4.5X0.75").
Cold filtered air is used to pressurize the lower chamber via the two 12-volt muffin fans (26dba, 120ma, and 2.75" diameter) and increases projector airflow and cooling. The front door of the box has a 3" wide plexiglas disk recessed directly in front of the lens. The front door is mounted on two self-closing kitchen cabinet hinges, and the door closes on a gasket made from 1/8"X1/4" adhesive closed-cell weatherstripping.
An additional feature is there is a 12-volt battery backup for the muffin fans that kicks in during a California "rolling blackout" and keeps air flowing through the projector until it cools off, avoiding damage to the projector due to the lack of the automatic cooldown cycle. This was implemented with 8 "D" cell alkalines in two battery holders, and a 12-volt DPDT relay, all mounted on a piece of 1/8" masonite in the bottom of the box under the projector. Note I kept the 120v AC wiring inside a metal box for safety, while the 12v stuff runs around inside. Normal fan power is from a 12-volt "wall wart" power supply, and this also pulls the relay that selects the power supply. When the power supply drops offline the relay opens and connects the batteries to the fans. There is a DPST toggle switch to turn off both the AC and DC power after the normal 30-second projector cooldown.
Some things to note: two muffin fans are used for better reliability. I also confirmed that the VT540 has an over-temperature shutdown and alarm, had it not, I would have included such in the hushbox itself. I connected the PC remote control input to an unused serial port on the HTPC and use the NEC utility to control the projector - there is also the option of using an IR repeater inside the hushbox, but I simply open the front door and use the credit-card IR remote directly for functions not in the control utility.
It works well, looks good, and all I hear is the sound of silence.
I've been thinking of hushing as well. One thought that occured to me to ensure that the LT150 does not overheat with whatever you build, is to first buy two digital temp sensors and mount one on top of the unit near the the lamp, and the other near the exhaust fan (but not covering it).
After 1 hour note the measurement. This is what the hush box should match . How to see what the temp is? Many digital thermometers have the thermocouple at the end of a wire so you can put it inside the box and view the results from the outside. Once you know your implementation works, the sensors are just for show.
I also thought about styrofoam, but doesn't this material scorch (or even melt) when hot ?
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