There are many different elements which conspire together to create sustain in a guitar. Some of these are obvious, such as the guitar’s woods, the type or firmness of the neck joint, the pickups, and the interaction with the amplifier, and the room. But the nut of the guitar is often overlooked when addressing issues of sustain or tuning, especially for beginners. A poorly finished or improperly seated nut will interfere with the vibration and sustain of the string, and can wreak havoc with the tuning too. In fact, many players go straight for a tuning key upgrade to tackle a tuning problem without realising that the cause is the string getting caught up in the nut.
Here’s how it happens: the nut will split the string into two areas of tension: one between the bridge and the nut, and the other between the nut and the tuning key (add an extra zone if the guitar has a separate bridge and tailpiece). If the nut is cut smoothly the string can maintain a uniform tension across these areas. If the nut is not smooth enough or the slots are the wrong size for the string gauge, the tension can be mismatched. And when this tension mismatch is ultimately equalised by a string bend or whammy bar use, it’ll throw the string out of tune.
A poorly cut nut can also harbor sharp edges, which can make certain chords rather painful. A good tech should be able to sort both of these problems out at the same time. Expert guitar tech Joseph Price from Soxy Music explains his method: “The mod I do on the nut, which I call finessing the nut, is probably my trademark,” Price says. “I knock off each corner and round it over. If you look at the standard bone nut on an old Fender, they just tend to make it arch.”
Price says his trademark nut treatment is more like the fret-end finishing on an ESP or Jackson guitar. “It’s completely domed, and then I arch the trajectory of the profile of the nut,” Price explains. The way this is done depends on the string gauge and the style of the player. “If you bend a lot of strings, the strings have to sit in the nut so don’t pop out. But specifically on a steel string guitar where a guy’s mostly playing rhythm, you’ll see that the depth of the slot is less than one half of the gauge of the string. I picked that up years ago when I played a guitar that was custom built for Bruce Springsteen by Takamine, and it was absolutely beautiful. Incredible. There were no sharp edges anywhere. So I said, “That’s how I want it to be.”