I'm planning soffits for bass treatment using 2-3 layers of unfaced 2" 703 fiberboard panels stacked inside a wood frame with an outer fabric covering. I'm looking for a low cost fabric (relative to GOM) with high frequency reflectivity that would approximate the absorption characteristics of AT fabric plus an equivalent amount of fiberboard with FRK facing. This fabric can't be so cheap, however, that it ends up sagging over time. 
Also does the distance between the reflective fabric and the unfaced fiberboard have much bearing on the overall absorption curve? Due to the wood framing for the soffit, I plan to have about a 1" gap from the fabric to the fiberboard.
Thanks,
Darrell
Also does the distance between the reflective fabric and the unfaced fiberboard have much bearing on the overall absorption curve? Due to the wood framing for the soffit, I plan to have about a 1" gap from the fabric to the fiberboard.
Thanks,
Darrell
