What does fretboard radius imply, and the way does a 12-inch radius differ from a 16-inch one?—Hank Tortora

The time period fretboard radius describes the curvature of the taking part in floor of the neck. Practically all steel-string guitars have fretboards which have a topped middle—thickest within the center, and barely thinner alongside the sides. That is meant to make the neck simpler to play and extra pleasant to the fingers, although it’s price noting that classical guitars almost all the time have flat fretboards, which appears to current no hindrance to extremely technical taking part in.

The numbers used to explain radius are a measurement of the theoretical circle outlined by the fretboard curve. If you happen to had been to hint the curvature of the fretboard, and mission that very same curvature past the neck itself, it will type a circle whose radius matched the required quantity. Or, to place it one other method, in the event you had an ideal circle of fretwire with a diameter of 24 inches, then a bit minimize from that wire would completely match the curvature of a 12-inch fretboard radius.

A smaller radius can have a extra pronounced curvature. That is most frequently encountered on classic or vintage-spec Fender-style guitars with their 7.25-inch radius. That is considerably rounder than most trendy guitars and might current points with playability, notably for gamers who wish to bend strings. You may visualize these points simply by taking a can, bottle, or some other cylindrical object and a straightedge or ruler. Lay the ruler alongside the can, parallel to its lengthy axis, and also you’ll see that it touches alongside your complete size. Which means that the can’s floor could be completely stage relative to the ruler, simply as we hope our frets shall be relative to the strings. 

However the issue arises as a result of this excellent floor solely exists when the ruler is parallel to the can—as quickly as you pivot the ruler in any respect, it begins to rock round on a single level on the can’s floor. As a result of the nut is narrower than the bridge, the strings on a guitar aren’t all parallel to the neck centerline. Subsequently, the fretboard floor intersected by the string isn’t stage. Most often, this concern is sufficiently small to be theoretical, and the guitar will nonetheless play cleanly with out buzzing. Nonetheless, on guitars with very small radii, this may manifest because the notes choking or fretting out, notably if you bend strings. 

Issues get a bit extra complicated with some trendy guitars, which use a so-called compound radius. These fretboards usually have a smaller radius with extra curvature on the nut finish, step by step flattening to a bigger radius on the larger frets. This strategy is supposed to idealize consolation for various sorts of taking part in in several areas of the neck—chord taking part in within the decrease positions, and lead taking part in larger up. It additionally addresses the geometry concern described above, by successfully making a fretboard floor that’s conical moderately than cylindrical. 

It’s simple to repeat the experiment above with a conical object, and illustrate that it’s attainable to discover a excellent stage floor with rulers in a number of positions on a cone, even when they don’t seem to be parallel. These fretboards are extra time-consuming to provide, and their geometrical benefits are usually solely significant for gamers who hunt down a particularly low setup. For typical low-to-medium acoustic guitar motion, a cylindrical fretboard can actually be set as much as play cleanly and with out buzzes.

The truth is that the majority radii are very shut in curvature. Let’s contemplate two of the most typical radii, 12- and 16-inch. On the nut place of a typical acoustic guitar (utilizing a 1.75-inch nut width), the 12-inch radius fretboard has a distinction in thickness of .032 from middle to edge, whereas the 16-inch reveals a distinction of .024—a internet distinction of .008. That’s roughly the thickness of the lacquer on the again of the neck, and thinner than a light-gauge electrical guitar string. This can be a very small distinction, and one which could possibly be simply neglected by even a critical long-term participant. 

Besides within the excessive instances of the classic 7.25-inch electrics, or the dead-flat classicals, the variations between most typical radii are often pretty refined, and I’d hazard a guess that 4 out of 5 of my purchasers don’t even know which radius their fretboard has. If you happen to discover a guitar that simply feels particularly good, it’s all the time a good suggestion to search for the specs and take word—however loads of of us go their complete lives by no means needing to know what that exact quantity means.