Originally Posted by Frank D
If that is in fact true regarding DIRAC limits then that is very good news.
If you look at the dark grey regions to the left and the right, those get no correction. There's a handle on the boundary you can drag to change the size of the correction window. It will crossfade between no correction and full correction at the first control point.
On the "Target" image attached, you are looking at my theater with subs + Triad Plats (before changing them out for 212s). The room is symmetrical, so the left & right speakers are a very close match. Going lower with correction started to sound worse, so I stopped there. At the top end, I found that I could apply correction, as long as I followed the natural curve closely. Trying to add more treble extension sounded harsh.
The "BR" curve shows a couple Adam Artist 6 speakers in my bedroom without a sub, with much less bass extension. The speakers and listening position are placed asymmetrically, causing significant differences between the two speakers. If you look at the leftmost control point, where the correction blends out, you can see how the corrected frequency response is allowed to diverge outside the correction window. The speakers are "linked" in Dirac, which syncs them to the same target curve. They still get independent correction filters, though.
(A nice bonus for the Dirac SW license is that you can use it in two rooms.)
I haven't had a chance to tune the 212s to a point where I am happy with them, so no results to share, yet.
Anyway, if you don't want correction over 500hz, just drag the right boundary to 500hz. Dirac makes it easy to a/b test, to see which correction filter you prefer.