How and Why To Build a Hush Box For Your Projector 
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Written by Jerry Del Colliano   
Sunday, 01 February 2004

How and Why To Build a Hush Box For Your Projector
By Jerry Del Colliano
February 2004

As long as video projectors have been in high-performance A/V systems, fan noise has been an unwanted byproduct. In my early 20s, while working at Cello Music and Film Los Angeles, Mark Levinson and the Cello design team rigged a way to change the fan of the “Cello” (rebadged Ampro) eight- and nine-inch CRT projectors that we sold. While this ultimately became a service problem for Cello dealers, the reduced fan noise on the projectors was warmly received by our well-heeled client base.

Today, nearly 10 years after my days of designing and selling systems at Cello, digital projectors are fast becoming the king of the home video hill. While ultra-expensive CRT projectors still produce the absolute best video image, their cost, size, weight, need for service and pathetic resale values make the brighter, smaller and less expensive digital projectors far more desirable for all but the most extreme videophiles. One of the biggest advantages of digital projectors is their impressive brightness output, but that performance advantage comes at a price, and that price is heat.

Almost every digital projector makes enough heat to require an internal cooling fan, and that fan cannot be shut off without risking the inside of your projector going Chernobyl. Adding to the complications is the throw distance of many D-ILA and DLP projectors, which often forces projector locations closer to your seating position than you would like.

The solution to many of these new problems is a hush box, which in most cases consists of nicely designed cabinetry that goes around your projector with the goal of muffling some of its noise and keeping it running cool. The concept is simple, but the application isn’t always as easy as you might think. There are after-market companies that sell hush boxes, but they tend to be generic in design and large in size. I have yet to find a video company that makes a well-designed hush box specifically created to encompass a unique projector model. If you owned such a projector, buying a hush box from the manufacturer would be a no-brainer.

In designing my latest reference home theater and music playback system, I made a dramatic design change three-quarters of the way through a full renovation of my new house. I decided to move the orientation of the room from the short wall to the long wall. The good news was that my gigantic equipment rack could stay where it was and my seating position would be further from the screen (making the digital video look more filmlike). The bad news was that my projector and screen needed to be moved. Not only did I have to punch holes in brand-new drywall to run a beefy Transparent Reference RGB cable through my ceiling, I also had to custom design new solutions for my Madrigal Imaging D-ILA projector and Stewart Filmscreen 100-inch 4:3 screen. The front wall of my theater is floor-to-ceiling A/V software storage, so I opted to have my cabinet-maker build a soffet for me that extended an additional eight inches beyond the software shelves. From there, a hatch was made on the side of the screen soffet that allowed access to the screen for adjustments and possible service.

Repositioning my projector was a much bigger problem. I had designed the room with a sidewall to hide a big post and to allow for a side channel speaker, a wall sconce and (some day) art work. Now the partial sidewall was right behind the listening position and blocking possible locations for the projector. I needed to do some research on the maximum throw distance for my D-ILA projector, and subsequently reached the conclusion that I was best served by mounting the projector almost directly above my head when sitting in the “hot spot” of the theater. The best solution I could come up with for the room was to make an open bookcase that would be adjacent to the partial sidewall I had created to separate the theater and the dining room. The open element of the bookcase would allow for the rooms to feel somewhat open and would give me room for the projector.

My initial plan was flawed on many levels. As soon as I got my projector back from another performance improvement (a new bulb and killer software improvements) from video guru William Phelps, my contractor and I tested it poised on its feet on the top shelf of the new bookcase. First off, the fan was unacceptably loud when compared to my last installation, but this was far from my biggest problem. Because of the positioning of the screen towards the right side of the room and the unit’s large size (a leftover 100-inch 4:3 model from my last theater), I needed to push my projector about as far to the right as it would go in the new bookcase. While this left plenty of room for the seemingly military spec connections from my Transparent cables, it also pushed the projector very close to the sidewall of the bookcase, so that the exhaust fan wasn’t getting the clearance it would have had the projector been centered in the box. Worse yet was the fact that the intake fan on the top of the projector was also positioned very close to the drywall of the ceiling. These factors caused a choking effect, due to an insufficient supply of cool air available to the projector. This was not a good thing.

Digital projectors don’t do well when they fail. An old CRT can need a service call when it goes bad, but a D-ILA or DLP can really melt down, especially if it gets too hot. Much like a good high-end power amplifier, most digital projectors will literally shut down (or off) before they get too hot. While this protects your investment, it can ruin a screening of a movie or a live sporting event being broadcast in HDTV. Upon hearing of the dire situation, my contractor got creative with a solution that literally poked a hole in the ceiling (i.e., the roof of my house) and installed a fan that would suck heat from the projector box to the great outdoors. Another fan, for pushing cooler air from the room silently from the bottom of the box to the top and then outside, was placed below the projector on the bottom shelf of what would ultimately become the hush box.

My contractor Bill Conte, who frequently works on projects for Beverly Hills audio/video design firm Simply Home Entertainment, made a run to Home Depot for parts, while I headed across town to the “depot of pro audio” known as Pacific Radio located on La Brea Boulevard in Hollywood. What I found at “Pac Rad” was a pair of low-wattage, 120-volt whisper fans that would plug right into the electrical “J Box” that was connected to my projector. These fans are studio grade and very quiet – far quieter than the D-ILA projector. After cutting a six-inch hole in my drywall above the projector and installing a bit of tube from it that you might use as part of a clothes dryer, Conte lit a match and sampled the power of just one of the whisper fans. It sucked the smoke out of the roof vent like a Hoover. Actually, it was quieter than a Hoover. It was more like a Miele.

We now thought we were ready to install the rest of the enclosure for the box and seal up the projector. However, more problems were present after the contractor left for the day and Director of Content Bryan Dailey came over. With the lights dimmed and darkness outside, Dailey and I started adjusting the height of the projector to make the center of the lens on the D-ILA line up with the top of the screen. This initially required figuring out how to adjust the default roll-down height of the screen. Thank God for Stewart Filmscreen’s website. With a few twists of a screw hidden on the bottom of the screen (soon to be hidden forever), we were able to make the screen clear the height of my new Wilson WATCH center-channel speaker and also elevate it enough to clear the screen soffet. Things were looking good.

However, after further inspection, my contractor and I decided to take the hush box to the next level. He suggested we could line the walls of the hush box with foam insulation. It might help with the heat and would definitely keep fan noise from escaping the projector box. We had to remove the projector, but the cost for 3M spray adhesive and the (not-so-combustible) foam was a mere few dollars and the project only took about 30 to 45 minutes, which was mostly spent taking the projector out and reinstalling it.

Because of the thickness of the 3M foam near the top of the box, I encountered even more of a choking effect in terms of airflow. While the foam was a good idea in terms of sound and heat, Conte and I ended up taking the projector out yet again and removing all of the foam, as well as the drywall above the projector in order to allow vast amounts of air to enter the projector. The exhaust was still able to exit through the roof, and my projector has thankfully yet to shut off from heat.

The last trick we added to my hush box came from a suggestion by my electrician, Bruce, who found a heat-sensitive switch for the fans, which can be set to turn on when the box reaches a predetermined temperature. We simply plugged in this big switch and set it to 80 degrees Fahrenheit. It doesn’t take long for the projector to be active in order to make the fans click on. However, I now don’t need to worry about having to manually activate the fan.

If you want to go all the way with your music and home theater system, chances are you are going to need some sort of concealment for your projector. Hopefully, some of the elements of my installation will be inspirational for your individual situation. I strongly encourage you to work with top-level installers to make sure your video system is set up and tuned to the highest level. Always remember, there is no reason you can’t have the best-looking picture while enjoying music or movie soundtracks in a noise-free environment.

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