The bigger concern is a stiff enough cabinet that will not flex under the pressure that the driver creates.
Interesting; I learned something new. I thought a woofer mounted in free air (or in an open cabinet like an H-frame) creates zero pressure because the front and back waves are out of phase. Maybe I'm reading too much into what JohnK has to say about it?
http://musicanddesign.com/roomgain.html
Edit: What I learned was not to believe everything I read in this forum.
Those woofers still put a lot of pressure within the walls of the H frame.
"
A monopole, such as a closed box woofer, is a pure pressure source. A dipole, like a H-frame woofer, is a pure velocity source."
S. LinkwitzMaybe Danny just got his terminology mixed up? Understandable given all the drama in his personal life at the moment.
Also, I think if one were to measure the
panel resonance of a 20" H-frame constructed out of 3/4" plywood, they would find that the primary resonant frequency would be well above the cavity resonance (i.e. > 400Hz; that's roughly two octaves above the acoustic cutoff). This
might affect poorly designed speakers that attach their midrange baffle directly to the "bass box", but most of the better full-range
dipole designs have had decoupled woofers for the past 8 years or so, making this pretty much a non-issue for me.
Maybe I'll try some of this miracle damping material for kicks - if I can find someone selling it locally.