...Akin to a ported response, which is odd. Good though!
Not odd when including room gain and an amp with some boost.
This is a single Tempest X in 3 cu ft, downfiring, at the 1/3 point of the front (long) wall, full range. Note the varying effect of the filter settings; the 16Hz setting looks a lot like mad's curve below 40Hz. It's what I use.
Also note that features like the "spike" can vary strongly with mic placement. Here's some data for my room, dual subs, after Audyssey and PEQ adjustment.
The 4 positions are a ~3' diamond around an on-axis listening location. About the space you take up with hands on hips; mic positioned at your elbow. there's a 25dB dip at 41Hz, but localized so I'd never be able to hear it with both ears at the same time. Not worth addressing in my book.
Make sure you move your mic around before you determine there's a problem to fix.
PS the Ultimax series is comparable to the Tempest X at a reasonable price. Hard to beat, sealed or vented in my book.
I meant odd that there's room gain to 20hz and then stops dead. You examples (and the examples I have) shows that the gain extends lower, which is more normal. His result is a little odd and looks like what we'd expect from a ported sub. No big deal though.
That's the infrasonic filter... a good sharp cut-off. Boost and room gain up to that point, then it drops like a rock. Look at my native 16Hz fitler curve; very similar shape, right down to the overshoot.
You can't use the second chart as it includes Audyssey and PEQ effects.
I really like the way it turned out with the hammered paint. I bough it at orchard. They sell it at Home Depot too. Use a good roller so it doesn't shed. I sanded it down a little after to flatten it out. I rolled it on, then hit it again with the roller all in the same direction to get the desired texture before the paint sets up. The longer you wait to re-roll it, the more aggressive the texture will be. I waited a little long which is why I had to sand it down a little. After I used so semi black to get the color I was looking for.
I think it was a 1/2 inch nap. When I finished my statements, I rolled two coats of primer on. Then I rolled two coats of semi black on. I did not sand it and I got similar results. Maybe a little less texture. Either way I'm very happy with the results.