This evening I took and hour or so and played with subwoofers. BigE LilE 12 and a 20" wide BFM t39.
The T39 is loaded with a 3012lf, is 20x20x39. It's characteristics are very familiar to me, I've been using Titans ever since the T48 came out several years ago. I switched to T39's for size. To those of you who didn't come here from BFM or are not familiar with them, it's a quarter wave horn, cutoff frequency around 45hz, usuable response to 40. They are clean, strong and loud. Really loud.
The LilE is a 12" vortex loaded subwoofer. 18x20x34 IIRC. I measured it, and lost the note before I got home. It's loaded with the 18sound NLW9300.
I disconnected the tops and ran just subs at first. I used quite a bit of differing styles of music, but the best reference was the opening bass line to Led Zepplin's dazed and confused. I didn't do any test tones, no point until I get my software.
The t39 is more efficient and louder through it's passband. My rough estimate is about 3-4db. The LilE digs deeper. When the t39 runs out of response, the LilE still thumps. I'd say it goes to 35hz easily. I could match the output of the t39 with the LilE, even at full output of the t39. Just because the 18sound handles twice the power of the 3012lf. And it did it with the extended response. I'd say both are examples of the compromises you have to make in homage to Hoffman's Iron law. Loud, Low, Small, pick 2. The T39 trades efficiency for low response, the LilE trades some output for extended response.
Sound quality was a total wash. I actually expected the Titans to be cleaner, because of the filtration of the horn path, but it wasn't so. Both are clean and tight and strong. No flabby bass here. Testament to the vortex design that it did sound as clean as a horn.
What I haven't confirmed yet at least with my tests are vortex subs ability not to excite room modes, and be far more immune to placement. I have heard it when I listened to the system in Illinois. But I'm really interested to play with it. That alone would make them more versatile than the t39's. Horns are pretty picky about where you put them. According to Steve and Tom, the vortex subs pretty much don't care.
The only problem I've come across is I'm not getting any work done. I just keep getting distracted listening to these cabs.