Thanks, LT61, and "hardie board" is new to me.

Re Tom Tuttle, yes I would agree that it would take very high SPLs to excite a resonance in a concrete enclosure but this is conjecture on my part since I've never heard speaker enclosures made of concrete. However, if you follow the theory, once the resonance was excited, it would likely be at a very high frequency that might be audible.

Regards,


Alan Lofft,
Axiom Resident Expert (Retired)