Re: More double 18's in progress.
More bracing = less panel flex. Less panel flex = more sound.
The ports look to small.
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EXACTLY!
Years ago (decades actually) I had a regular gig and always took the same rig. I had been reading about bracing and decided to try it on my cabinets.
The next gig-same type bands-same PA and WOW-it was like I had brought twice the PA or more. The low end was so much tighter and louder. I was HOOKED on bracing from then on.
The bracing is not to prevent buzzes or rattles-but to keep the walls solid.
The perfect speaker cabinet would be made out of 2' thick concrete or something like that.
The more sold the cabinet-the more sound that will come out and not be absorbed by the wall "vibrating".
And yes-even small movements will be absorbing the sound.
I prefered to use a solid piece of wood down the middle of my 2x18's (back when I ran them). So it was actually 2 cabinets in one. That way if one driver failed the other would not be detuned.
The divider also made a good brace.
Agreed about the ports also. But of course a larger port would require a larger cabinet.