ToTo Man
the band not the dog
SWMBO has agreed to a corner trap, and I'm hoping I can sneak in at least a couple of wall-panels (something like the GIK 244 or Monster Bass Trap). I may measure the room again later today, as I've reorganised a few things and my previous room measurements (see below) are likely now invalid.
As you can see, it's pretty flat +/- a few DB except for the big mountain at 32Hz; this is the axial room mode for length (i.e. ~18') which I hope to tame by a corner trap, moving the listening position slightly away from the back wall and maybe a couple of panels. I have to stress that the sound is pretty damned good already - this isn't a question of fixing something that's broken, more a matter of improving it further, if possible.
Your in-room low-end response looks quite good TBH! . In agreement with others, conventional-sized broadband panels or corner triangles won't touch a thing under 50Hz. I'd be more interested in viewing the waterfall and RT60 graphs to see what the decay times are like across the frequency range shown in the above graph, as IME long decay times are more unpleasantly audible and problematic than a peaky/dippy frequency response.