I have to get my mind around the discussion here on the equilateral triangle vs. "90 degree" option and that's a big change in my process since I've been thinking all along I'd be doing the equilateral route.
The 30° toe-in angle for a 60° equilateral triangle is often claimed to be the "optimal" geometry, but in a study done on many top studios done like that, it was found that most engineers prefer to be a bit further forward than that, and some (very few) prefer to be a bit further back.
In reality, the angle can be whatever it needs to be to fit into your available space. You can go as much as 45° toe-in angles (90° intersect) if needed, but that's pushing the limit, since you start to get shadowing from your own head and start loosing accuracy in the sound stage. And you could probably go down to about 20° at the other extreme.
Our ears and brains are pretty sharp at figuring out where sound is coming from, so the actual angle is not cast in stone at 30° toe-in. If you make it 34° or 28° or 41.6463543°, your brain can deal with it. What is more important than trying to peg angle, is to ensure that the room is symmetrical, the distances from your head to the speakers are identical, and the room is treated accordingly, to get the most neutral balance of sound possible, in both frequency and time.
I've wanted to have the capability to test the floor/front wall with a sealed, hard surface versus an opening to a bass trap and plan to have that as a modular option.
You mean using part of the internal cavity of the soffit for bass trapping? That's a smart way of doing things, since it optimizes the use of space. If you don't do that then you are just wasting a lot of space, as there isn't much else it could be used for. John's soffit design incorporates hangers below the actual speaker shelf, and that works very well. You need bass trapping anyway: that goes without saying, so you might as well make use of that otherwise wasted space inside the soffit!
- Stuart -