Re: Speaker Splaying - the definitive guide...
I've done this excercize - put the speaker on the floor and run low-volume pink noise through it. You may want to band limit it to 500hz and up, but at low volumes it will probably work full-bandwidth too.
Start with your head on axis with the tweeter and move to one side. Though there won't be an exact moment where the sound will disappear, there is often a fairly defined point where a lot of the highest frequencies go away. Put a piece of tape on the floor at that location, then repeat on the other side of the cab if you would like to confirm your results.
Draw a line from the back corner of your cab to your tape and you will have the centerline of the cabinet splay. For easy figuring, measure the distance from the front corner of your cab to your line and then double it. This is the splay of the cabinets with the backs touching.
Confirm your results by setting up both speakers at this splay angle and walk the pattern. The goal is to minimize comb filtering, so play some music and see how it sounds. Experiment with cabinets splayed in a bit and out a bit of your initial guess and see what happens, then whatever sounds best - do that.
