http://novaxguitars.com/sales/ch8.html
"Fanned" frets
There's two main factors for a given pitch of a string: Length and tension. For a given tension, Longer length will give you a lower pitch. So logically enough, Lower pitches work best with a longer length. You can tighten the string more to reach a Higher pitch, but that has undesirable effects (breakage and a 'shrill' tone). The same in reverse: For a shorter length, less tension gets a lower note; and it's absolutely possible to not have the string tight enough to perform well. Think of a grand piano from top down, and you get a good visual of what I'm trying to describe.
A standard guitar is about 24 1/2 inches from nut to bridge. A bass guitar is about 34 inches
(and often longer for a 5 string), to accommodate for the tension needs of the lower pitch strings.
On a 'Fanned' design, there's a different overall length for each string in order to more optimally accommodate for the best balance of tension. Ralph Novak came up with the idea, and it works well for Charlie because Mr Hunter combines 5 and 6 strings of an electric guitar with a two or three bass strings.