[Schuyler Bain]

Are there any good recommendations on the best type of material to use for the window on a projector box?

I've seen this one mentioned before. Little pricey...
https://www.edmundoptics.com/optics/windows-diffusers/visible-windows/8quot-x-10quot-size-plastic-optical-window/#specs

I know the glass/plastic isn't necessary, but I'd like to contain the fan noise as much as possible. Putting glass on also means I'll need a larger intake vent on front of bottom hatch (4" x 8"). Concerned that the large vent could leak as much fan noise as just leaving the glass off the front in the first place. Thoughts?

 

[DaveClement]

All glass (and transparent plastic) will reflect some light. Best practice is to tilt the glass slightly so that it won't reflect back into the lens and then bounce back out to the screen, where it can cause "ghost" images.

You can mitigate sound transmission from your air vents by making a short "tunnel" that forces the air to go around corners, rather than in a straight line. Line it with Linacoustic or similar material to minimize sound reflections. The larger that you make the air vent, the lower the air velocity, which will translate to a quieter vent.

 

[Schuyler Bain]

All glass (and transparent plastic) will reflect some light. Best practice is to tilt the glass slightly so that it won't reflect back into the lens and then bounce back out to the screen, where it can cause "ghost" images.

You can mitigate sound transmission from your air vents by making a short "tunnel" that forces the air to go around corners, rather than in a straight line. Line it with Linacoustic or similar material to minimize sound reflections. The larger that you make the air vent, the lower the air velocity, which will translate to a quieter vent.

I have a cool cube placed externally, up in the soffit to pull air out of a 4" hole in the projector box also lined with linacoustic. Planning to attach a 4" (diameter) duct/tunnel to the exhaust (front) of the projector, which will bend 90" degrees and connect to the cool cube.

Just wondering if the intake vent on front of bottom hatch (4" x 8") will leak much sound? My projector's air intake is also on the front directly above the 4X8 vent.

I don't have the bottom or front on the box now. The only thing I can think to do is create a mock up - cut out on pieces of cardboard. Test with open window & smaller vent. Then test it with window closed/sealed and larger intake vent to see what's the quietest.

I have another 4" hole letting air into the soffit on the opposite side of the cool cube as well.

 

[DaveClement]

There are really three sources of noise; the exhaust fan at the outlet side, the fans in the projector itself, and the noise of the air going through the intake vent. I'd be inclined to go the cardboard mock up route. Just know that it likely won't work as well as heavier materials for blocking the exhaust fan and projector fans. It will probably be enough to give you some indication of how well the final version will work.