"If you were to lay a circle centered on both the x-axis and y-axis and trace around it’s perimeter, you would have gone... 4Pi when you get back to your starting point."
No. Once around a circle is 2pi which is the ratio of the circumference to the radius of the circle. 4pi refers to a sphere which is the ratio of the surface area to the square of the radius. 2pi is the surface area of a half sphere.
4pi is called full space. 2pi is called half space. Both refer to how radiant intensity is measured. When a bookshelf or floor-stander is spinoramad, the radiant sound power is computed from the intensity incident on the area of a sphere. When a wall-mount is spinoramad, the radiant sound power is computed from the intensity incident on the area of a half sphere. This radiant sound power is referred to as the "sound power" curve. It's a curve because the sound power strength varies with frequency.
One thing I don't understand is why some manufacturers install the tweeter faceplate flush with the baffle and others, like Axiom, stand it a bit proud. Perhaps this is a tradeoff between reduced baffle edge diffraction and higher faceplate edge diffraction? The faceplate edge diffraction would take place at higher frequencies than the baffle edge. Perhaps diffraction at higher frequencies is less objectionable or easier to compensate for.
