Rerurn to Romy the Cat's Site
In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s Midbass Project – the grown up time.
Post Subject: R-Value and Damping OptionsPosted by Paul S on: 7/26/2010
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Plenty to chew on, here, including the minimum R-value (30?) one would want for attic/roof insulation in that part of the world. I know of no styrofoam that provides R-30 at 2", but it is the end value that is important, along with code-required flame resistance. What sort of insulation to use in this case will be determined by available space in some cases and the ultimate choice of closed or open-bay systems used, if some rafter bays must be "closed".
Romy made reference to a system that somehow combines foam with sand, but I would think this could compromise either or both insulation or damping, if the exterior of the horn itself were coated with this stuff. Based on what I know now, I would first coat the horn with modified cement mortar, then I would coat it with appropriate insulation, likely some sort of specialty foam, like they use for commercial freezers, cold lockers, duct work, etc.
With the "new-type", "closed bay" system, one MUST use foam or the like rather than anything loose, like fiberglass, the idea being to prevent the sort of "steam" that can form, especially in flat roof and deck joist bays, in hot weather, along with the condensation that subsequent cooling can bring. OTOH, if a full ridge vent is used and the attic is otherwise well-ventilated, one might simply insulate according to R-value and not worry about foam vs. fiberglass, open vs. closed bays, or whatever.
Best regards,
Paul SRerurn to Romy the Cat's Site