Many Thanks Merlijn, Very nice.
Trying to get an intuitive feel for aligning to 1/3 oct above crossover.....and for aligning to rear...
Are these mainly due to trying to overcome the geometry of sub-to-main separation?
I get the point about longer wavelengths allowing more wiggle room to offset relative distance changes.
I'm also thinking that the increasing sub group delay (as freq drops) is working to advantage to overcome moving closer to speakers too ...
If subs and mains are adjacent, would you align to x-over freq, or 1/3 up?
Oh, I assume the calculator is seeded with LR24 .....?