Here is the T-6.
This is a ~6 cubic-foot tapped horn that can use 8" or 10" drivers. It provides solid performance to 30 Hz. Not much below that - I chose small and loud, so I had to give up low. No bracing, no fancy cuts, and it is quick to build.
As built, mine are 23 7/8" wide, 35 7/8" long, 12 3/4" deep. The design is very flexible - you can run the mouth out the side, like mine, out the end, like the Insubnia, or out the bottom, whatever best suits your placement. The cabinet can be made thinner and use smaller drivers (The Exodus Anarchy works well, as does the Tang Band W6-1139SI).
Here is the 1W 1M groundplane compared to the model:
And - per Bosso - here is a "proper" compression plot measured at 1M groundplane, at 1, 4, 16, 64, and 128 watts.
Mine are built with Tang Band W8-740C drivers, because I had some. The Apex Junior Super 8 also works well, as do a number of other drivers. I'll start that list in the next post.
I've attached a set of instructions, a cutlist, the sketchup files, and a pair of models, one with an 8, one with a 10.
Yes, this looks like the tapped Insubnia. I decided there was too much wood left over after cutting the parts for one of those, and wanted to see how much sub I could get out of a single sheet of 1/2" plywood. So - I made a sub as large as I could and still have it all cut out of a single sheet.
It turned out pretty good. I am currently listening to a pair, loaded with 8s, and I really don't find them to be lacking. I'd have used 10s if I had them, but as I have a number of 8s, buying more drivers was not an option. As it is - I am able to exceed 115 dB at the couch above 30 Hz with the pair.
I strongly suggest running a highpass between 25 and 30 Hz with these. The Tang Bands are at their limits at ~128 watts, and made some noises before that during sine-wave sweeps. I've not noticed any complaints during movies or music though, and I have run them plenty loud.
A good 10 (TC Epic, Kicker CompVX, or similar) will add 6 dBs to what the W8-740s can manage.
Edit 11-1-2011 Added "tarted" version, fixed errors in cutlists.
Cinema T-6 Instructions.doc 446k . file
Updated T-6 Cutlists.zip 12.154296875k . file
T-6 Sketchup.zip 86.9599609375k . file
t-6 models.zip 0.75390625k . file