Tumara Baap
70.162.180.137
In Reply to: Ceiling trap posted by T-Rex on September 6, 2006 at 04:20:04:
I'll soon be doing a similar room. The ceiling recess is best stuffed for purposes of low frequency absorption. For a room that size, bass distortion will be the main issue. My ceiling has joists spaced 24 inches apart. On these joists I plan to lay down some 2 inch thick mineral fiber boards. And above that I'll push in fluffy R-38 insulation where possible (ceiling recess is crisscrossed with ventilation ducts, cables and gas pipes). I don't think you really need to have insulation stuffed up all the way... particle velocity is essentially zero at any wall boundary surface and little absorption will take place there. Most of the absorption should take place at the mineral fiber boards, about a two foot drop from the upper floor boundary. Before dressing things up, this should be an opportunity to run any HDMI or CAT-5 cabling in the ceiling space. I'm not sure how to finish up the ceiling, as I'm afraid a simple breathable cloth covering may sag over time, and there's the issue of using trim and crown molding to cover up the countless staples. Maybe using something rigid would be easier e.g. GOM covered 1 inch 703 affixed to the joists with snap-on rotofast anchors. A concern with all this treatment is the ceiling would make the room too dead (although the room will have hardwood floors). At the very least having diffusion interspersed in the ceiling should make the room more natural sounding. An idea was to use a few FSK/FRK 703 pieces but to drill holes so as to afford Binary Amplitude Diffusion (I hope the grids by Trevor Cox on his website are an accurate representation of an actual BAD panel). Or one could even use the BAD Arc panels from RPG. I think BAD panels offer only modest diffusion but are better than a straight reflector or absorber. BAD's should simply add to the absorption by the insulation above them.
Tumara Baap
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