Happy holidays everyone! Back with an update after a move.
The new room is a more favorable shape, rectangular and roughly twice the volume from previously at 23'7'' long x 12'4'' wide x 7' 7'' tall. A bit of a lower ceiling but it's a finished basement so that's to be expected. Along with the walls and floors being solid CMU and 100% reflective. The ceiling is drywall.
The speakers are set up full range on the short wall around 2' 8" from the wall, and 3' from the side walls. The back wall is 13.5' from my listening chair and I am 7' 8'' from the speakers. (10' 2'' from the front wall) The subwoofer is positioned at the front left corner about a foot from the wall in either direction, just behind but still very close to in line with the speakers. I still do not have any EQ implemented beyond what's available in the RME DAC (needs further adjustment) and the PEQ on the sub (finalized).
The new measurements show a better looking FR graph, albeit with a peak and resonance around 50Hz even after PEQ, and a drop off in the sub bass pressure since my single Rythmik L12 can't properly sustain the new room volume:
The resonance is better seen in waterfall & spectrogram visuals:
According to 'amroc' the worst offending node(s) seen here gather in the four corners of the room:
I ordered a few more monster bass traps to stack in the corners from GIK acoustics, for more square footage absorption in the larger space. But they are several weeks out in production so I won't see them for over a month, and then some. I need to add a second Rythmik L12 which I can get much quicker than the panels I ordered to restore sub bass response as well as try to knock out that peak and resonance. The RT60 is great until 60Hz where it laughably goes vertical, and off the chart.
So where do I put the second subwoofer? Do I move the corner loaded sub? I had it between the mains before and there was a lack of bass around my listening chair, hence the corner move.
Research suggests the most effective solution is opposite diagonal corner so I can try starting there. Thankfully I can set the two subs individually at the back for phase and PEQ while listening to music. But for HT my receiver only has distance for 1 sub. It has 2 sub outputs but technically it is only a 7.1 receiver, not 7.2. So placing the second sub as equidistant as possible from my chair in the opposite corner makes the most sense to me as a solution to all of these things. Unless I'm missing something? Which is why I'm here!
Any help is appreciated!
Cheers