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Hushbox 10/20 |
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The hushbox for the projector is built with a 1x2 pine frame and 1/8 hardboard. | |||
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Everything is glued and nailed with a finish nailer. The black stuff is asphalt adhesive to hold the fiberglass ceiling tiles for noise insulation. | |||
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The opening is big enough that the projector front can stick out. | |||
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The seams and nail holes are filled with drywall filler | |||
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The finished box is hinged on the front. It would've been better to hinge on the back but the only joist for the hinge was at the front. The orange plug in is a temperature controlled switch which turns on fans pull air through the duct. | |||
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This quieted the projector down a lot. I still get fan noise from the intake fans on the front of the projector. | |||
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The next step was some waffled sound absorbing foam. Glued to every surface. The projector case was removed to improve cooling. If I were to do it over, I'd put the plastic side on the fiberglass out. | |||
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I put some rheostats in (3) of the fan power supply wires to vary their speed. Just turning them down a little helps lower the frequency of the fan noise. | |||
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Success. The projector is extremely quiet now. I don't think it could get much quieter without reducing the fan speeds to far. The front door is hinged so I can still get in and do mechanical focus adjustments. All the foam and reduced opening size did increase interior temperature during operation. Interior temp gets up to 100F vs 95F with just the fiberglass. | |||
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This is the 6" insulated duct that comes out of the theater room. A digital thermometer was placed on the ceiling in the hushbox. | |||
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2 Fans in series provide the airflow. One is a six" and the other the 8". The 8" was an afterthought when I decided I didn't have enough airflow. With losses I should be pulling about 200-300scfm. | |||
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