home theater sub enclosure

Did you even look into the site I linked for you?

How much space is behind this wall?  Meaning, starting from the wall with your 7X20" opening, how far back can you go?

The slot' for each sub would be at the bottom left and bottom right, the actual enclosure would be behind the TV, since the compenent rack is filling up the bottom portion of the area.  I realize this is a somewhat radical idea, but I'm just trying to make do with the extra space I have back there.

Here is a see through of the subenclosure, and the slot the will have to channel the bass into the room.

Okay, so where are you telling me to mount the speaker?  I don't think I understand what you are saying.  The way I see it, the bass has to be fed into the listening environment via the 'slot' or, "port" either way.  So regardless, it seems even if the other side of the woofer in in an IB, facing it into the port, it will still be a bandpass, just single reflex, vs dual reflex.

As this website explains it.

Using IB would result in this...

Using my ported enclosure would result in this...

If it really is going to behave like a bandpass, my only option is to try to design a bandpass on purpose, so maybe I can actually tune it as best possible.

This is the main reason I would rather use ported vs IB.  The red line is my vented enclosure, the orage line is IB.

Well, you are all right, I tried playing around with the bandpass tuning out of curiosity, and it doesn't look too good.  Originally I was designing it thinking it would just be a ported enclosure, not being affected by the 'slot' but I guess this is not the case.  I never actually wanted to use a bandpass of any sort.

As for the use of 8" subs, I would be fine with that, but there is only about 4.5" as is, those grills are 7.5" wide, and for the front speakers I was already cutting about half way through a 2x4 on each side.  I was stretching at the idea of even having 7" width for the sub, plus the grills would have to be bigger.  I'm looking at it now, and I'm thinking, I might be able to fit some 8s if I angle them at 45 degrees or something, not sure how that would affect the sound.  But if it could sound decent, and I could get it to fit physically, I'm open to it.

As for the TL, I haven't actually considered it, and have little knowledge in that area.  I'm not even sure what benefit that would provide, or how it would be applied here, I'm open to suggestions as the idea for the sub behind the TV seems to be a no go, be it IB or otherwise.

Another part of the problem here is that I live with these complete wierdos, whom have their priorities all mixed up, and can't seem to grasp the fact that loud and clear rumbling throughout the entire house is truley important to the continuation of life as we know it, and we will all seize to exist if we don't feel T-rex coming 5 minutes before he gets here. =D

Now I'm thinking even 3 6" on each side might fit.