I just curious...was/is there some kind of plan with all the different panels/boxes/curtains/etc...or did you just go for the "more is better" no matter where/how it's placed?
What problem(s) are you still chasing...besides the dead room result?
There's appoint where you really can't correct the low end much further no matter how much trapping you add. I mean, you would have to practically fill the room...but even before you get part of the way there, you end up with a dead room...so you don't solve one problem, but you create another.
It may be an obvious thing...but volume is what really makes a difference...and you want some kind of reverberation/life in the room.
There really wasn't any sort of plan, per se. I started out with the basic theoretical suggestions that almost always characterize room treatment advice: corner bass traps, panels at the first reflection points, a cloud above the speakers/mix position, and some panels to cover large areas of open wall space. I also added some curtains for mostly aesthetic reasons
A some years later, I dove into room testing and analysis and simply let that guide me to wherever it went. In the process, I added traps, removed traps, reconfigured traps, and basically played musical chairs until I reached the numbers posted in the other thread.
Along the way a learned a lot, got plenty of advice (some good and some bad), and certainly came to the realization that all this would have been easier with a paid consultant. Easier but more costly and less fun.
When I started, I knew that the room was a problem room because of it's dimensions. And I knew that it would require substantial trapping to exert any level of control over the low end. I also knew that this would lead to certain sonic irregularities, including an overly dead space. For me at least, I was willing to accept this tradeoff. I don't record bands, other musicians, or anyone else for that matter. Only myself. And my music is simple and basic. It does not require a huge soundstage, It's not orchestral, or EDM, or stadium rock. I play mostly acoustic instruments which are often close-miced. So I'm less concerned about the deadness issue than others might be.
My measures of room reverb are consistent across frequencies (especially 250hz to 4k). They are also within the parameters for most small, home studio environments. They may not match BBC control room standards but I'm not the BBC.
I should also point out that this is an evolving process. Some would say a never ending process. So what you see here may change. The pics basically show my current placement as the result of a stepwise, data-driven approach to studio treatment.