I read a few interesting discussions about fretboard radii recently – comparing a traditional straight radius to the newer (as of 30 years) compound radius.  First some background:  The fretboard radius is the curvature of the fretboard.  A straight radiused board has the same curvature down the whole length of the neck, while a compound radiused board typically has a smaller radius near the nut (more curvature) the flattens out as you move toward the bridge.

Most marketing bills for compound radii talk about how the tighter radius at the nut makes chording more comfortable, while the flatter board at the higher frets near the bridge makes soloing easier.  There is, however, another factor to consider.

Basically, with a straight radius, the fretboard is arched as though you cut the neck from a cylinder that runs the length of the neck.  Because the bridge has a wider string spacing than the nut, this means that on a flat (not bowed) neck, the strings will be closest to the fretboard in the center, where they have the highest amplitude while vibrating.  Think of it this way:  If you run a string straight down the length of a cylinder, it run straight just fine.  However, as you start to shift one end to the side (as the edge strings are with respect to the curvature of a straight radiused fretboard), the string will start to twist around the cylinder.

On a compound radius board, you don’t have this problem (or you at least have less of it).  Ideally, the radius will scale with the string spacing, giving you a fretboard that looks like it was cut out of a cone.  The strings all run straight down the cone, rather than at a slight twist as on the straight radius.  As a result, all the strings will be the same height off the fretboard across their entire length.

Theoretically then, a compound radius should let you set your action just a little bit lower before running into issues with strings buzzing on the frets.  I’m not sure how true this is in practice, but it certainly is an interesting thing to consider.