Originally Posted by Sjogras
I still don't see any difference to "ordinary" drum heads, since solving the level 360 concept seems to be making a drumhead big enough to lay evenly on the drum. And as far as I know, Aquarian already has oversized drum heads for vintage drums. What exactly will the steep collar do for the sound?
You have to be more specific in regards to explanaining exactly what these drum heads do.
The idea is that the entirety of the collar should be on the hoop side of the bearing edge. If any part of that formed collar area is inside the bearing edge, which is the playing/resonant surface, you will need to tension the head tighter to overcome that formed shape to pull it tight, which will be at some tension higher than if it was only the flat part of the head on the bearing edge. But also, just because you've overcome the form shape doesn't mean that its own tension isn't still there subtracting from the resonance.
Making the collar as vertical as possible increases the chance that no part of it will be seating on the bearing edge allowing for lower tunings with minimal or no head distortion.
Again, all heads should be designed so that the formed collar stays off of the bearing edge. Different drum companies use different diameter shells with varying placements of bearing edges on the shell, so head manufacturers can't (or should not be lazy) about their collar formations. They should spec to worst-case edge diameters.