I thought I would post a little subwoofer project I have been working on. I had planned on building a couple 18" diy subs to add to the theater. Currently use a 15" mfw15 and my old 12" Athena sub. These are not the greatest but did a decent job of pressurizing my sealed, 2700cf room. problem is they did not go below 20hz at the output I was demanding and the AQ was questionable.
I purchased and cut 3 sheets of 1" mdf to make the subs modeled from a popular 18",5cf, sealed design. The more I got in to it the more I realized how psycho folks are with their bass (

) and saw diyers going real big with their boxes. I was doing, what I thought, was a big a 2 foot cube/5cf and many folks where going 2 or 3 times bigger for their boxes at 10-15 cubic feet.
Then I discovered the infinate baffle design for subs. This basically turns an adjacent space like an attic, crawlspace, closet or room into a giant sealed subwoofer when you install a driver(s) between the spaces. Supposed to be performance benefits to something like this and MAJOR WAF if you can deal with cutting a hole(s) in the wall.
I am halfway through the project and have installed two 18" drivers on the right side of my screen wall. A second pair will be installed on the left side and all 4 drivers will be powered by a 4000 watt Behringer ep4000. The difference between this set up, even halway completed, and my old two box subs is gut wrenching. I could not be happier with the pure tone and output already. Whatever increase happens when I add the 2nd pair - is gravy.

I am more posting this for folks with dedicated rooms or planning rooms to look at as an option. I wish I knew about this when I was building my room. For under $1400 I can't imagine a better performer with this high of waf.
I friend of mine is building 2 18" box subs and we will do a shoot out and will be interesting to hear/feel any difference for the comparable cost of each.
The project is not finished yet but here are some in progress pics.
before picture

Blurry pic of 2 drivers installed on the right side. When I finish there will be a black, AT, fabric screen over the area that the drivers cut into the screenwall where the screen is. It will look like side masking to match the masking at the bottom of the screen area. The posters will go back up and I will cinch them a little tighter together. You will not know the sub is even there.

The back side
