Originally Posted by BrolicBeast
Question guys, I'm thinking about building a projector hush box, and then connecting it to the rear soffit and running a 4" flex duct to the 8" return flex duct already in the rear soffit. Good idea? Bad idea? Do I need an air intake? Should I even bother connecting it to the rear soffit return, vs. just using silent pc fans?
Do you see what happens when I take time away from this thread to post in my own thread?? Do you see??? You've gone and jumped the shark again without proper supervision!!!
With how quiet today's projectors are, I am very against introducing the complications of a hush box for what amounts to extremely limited sonic benefit. Can you hear the projector if you are sitting right underneath with all audio off and nothing to do but focus on the projector noise? Yes. Can you discern the sound of the projector once *anything* is playing at normal volumes through the audio system? No....or barely if it happens to be a quiet scene and you're not already immersed in the content on your screen.
Let me give you some free advice:
- If you do not use thermostatically controlled exhaust fans, you risk unnecessarily over-ventilating your projector box which is engineering-speak for drawing significantly more dust through your projector and projector box which will shorten your projector and projector bulb's expected lifetime without regular deep cleanings. Plus the lens will get dirtier much more quickly.
- If you connect the exhaust directly to the return of your HVAC system, you risk unnecessarily over-ventilating your projector box which is engineering-speak for drawing significantly more dust through your projector and projector box which will shorten your projector and projector bulb's expected lifetime without regular deep cleanings. Yes, you can use a baffle to control the amount of air, but this generates its own turbulent air noise. Plus the HVAC system is drawing air through your projector box anytime it runs, even when the projector is off.
- Even if you build a five-sided box because the JVC intakes / exhausts from the front, what about the next projector?? Are you going to shop only for projectors which rely on this front-positioned cooling air path?
- What if your next projector is physically bigger? Do you plan to overbuild the dimensions of this hush box, adding the necessary 2" to 4" spacing between the edges of the projector and the face of the Linacoustic?
- Without thermostatic control, how can two "silent" fans mounted through the sides of this hush box be better than the fan buried internal to the projector? Even with thermostatic control, is this still considered 'better' without the fans being remotely located? And I can tell you right now the computer fans aren't nearly strong enough to create duct pressure sufficient to ventilate when placed remotely.
- Ventilation is always forced exhaust and passive ingress, which immediately kills the idea of using two fans in the first place.
Hush box ventilation needs to be its own, separate system with thermostatic controls. Ideally the system will use an in-line impeller fan of the appropriate size. The maximum exhaust duct size is 4", but 3" is a good balance of duct pressure and air velocity to overcome the static pressure of the hush box and encourage fresh air ingress sufficient to match up with the required BTUs. Do not make the box tight to the projector, but minimum 2" underneath and 4" on the sides. If you fully enclose the box, invest in optics-grade glass called "white water crown" or "float" glass to preserve your projector's picture quality with as little light loss as possible. The distance between the glass and the projector's lens must be taken into account when installing viewport glass in front of the projector. Typically speaking, the glass should be installed anywhere from 9-15 degrees at an outward angle to prevent light reflection back into the projector's lens.
I could go on, but I hope this is enough for you to consider and junk the idea at this point unless there is some dire aesthetic reason for this box.