Calculation and yes in my room. My speakers ended up 44” to front wall at tweeter due to longer room.
I work with fixed ratios of 0.2/0.32/0.45/0.55/0.68/0.8. These are room mode avoidance ratios identified by Grimani, but in the book you picked up too. Just math. You can mix the ratios so long as speaker seperation is around 0.7-0.85 or so of distance from listener to speaker plane. Screen size of 1.13x diag to viewer supports this for transparent setup.
Anyhow, for this room 0.2 of 11.5 x 15.5 x 8. works well.
Curious about yours? Your planned screen breaks the ideal setup, but I can PM you the #s if you are curious. Or pm me another room and I can spit you #s so you can temp with LFRs etc.I do this before going to any freestanding install to save time in design phase.
In my 2ch room you can sit anywhere between the speakers and center phantom stays in front of you. Diffuser no doubt a part of that. No vice!
No modes. Uncanny.
