Originally Posted by Stereodude
When I posted I knew you'd be along shortly to claim user error.
Wow, you must be psychic.
The Tumult MKI wasn't designed for a flat-to-200 Hz response. It's a SUBwoofer driver, made to cross around 60 Hz, although, as I've already shown about 2 billion times, it works just fine with proper signal shaping giving a very formidable 5.5 liters of displacement to the bottom of the room/signal chain.
The CSS-SDX-15 is the Tumult MKII. With a redesigned basket, it looked to be a spiffy 15, but never appeared for purchase, and probably never will. Sundown has adopted XBL^2/Wiggins designs and one other I can't recall, so similar performance there with a bit less displacement. Good stuff in any case. Certainly not paperweight, which really is a rookie thing to say.
ain't my cup-o-tea, so I can't help you there, but signal shaping is an inevitable part of low end reproduction in-room. Whether you do it pre or post, you'll do it. I obviously prefer no post EQ and prefer to shape the signal before the room with a signal shaped response that is predictable as working best with the room and listening preferences. Afterward, placement, delay and crossover selection options will fine tune well enough in most every case.
Build a sealed box and a simple L/T from Linkwitz's spreadsheet (or some outboard EQ if you prefer a costlier pre-built outboard solution), use a good amp and there ya go.
Also, when you measure close-mic, put the LPF in line that you use in your HT. That'll save you a lot of fretting over nothing. So the AV Vaporware-after-I-waited-2-years=for-it driver is relatively flat to 300 Hz, what does that mean in actual use? Nothing.