By Tom Mulhern
Over the years, I've heard people discuss (and at times passionately argue) that the "breaking angle" of a string passing over a guitar's nut is ultra-critical. To what? Well, some say sustain, others (more vaguely) say tone, and still more say tuning stability. There are multitudes of Gibson-, Martin-, Gretsch-style guitars, utilizing different downward angles of strings passing over their nuts and into the mouths of their tuning machine posts. At the same time there are zillions, give or take a billion, Strat- and Tele-style guitars, often with far shallower breaking angles. And yet, somehow, a lot of guitarists like them, don't feel they're being robbed of tone, cheated out of sustain, etc.
Lately, a certain ad (honest, I’m not trying to make trouble for the ad director or editors!) has put this discussion onto the front burner, so to speak. Think of it as a physics lesson filtered through a marketing department. That is, the concepts are good, but so much spin has been put on them that they begin to smell like unsupported hype. They present the angle at which a string breaks over a nut as either "right way" or "no way."
So, what gives? Well, like many other concepts in guitar design and history, the breaking angle is just part of the story. That is, you have to look at the "big picture," the guitar as a system, where every part contributes to the sound and overall function. As anyone who has put single-coil pickups into a Gibson SG Standard or humbuckers into a Stratocaster can tell you, their guitars did indeed sound different afterwards, but the SG didn't sound like a Strat, nor did the Strat sound like an SG. Wood, neck material and attachment style, scale length, bridge type, and many other factors also come into play in a guitar’s playability and sonic character.
Yes, increasing the breaking angle over the nut can give a string more downward pressure, and therefore more sustain. But, gee, what if the breaking angle over the bridge saddles is kind of shallow? In theory, then, you’d maximize your sustain by having a mondo steep angle at both ends of the guitar. And think of this: Once you put your finger on a string to fret it, the "sounding length" of the string is no longer between the nut and the saddle; it’s between the finger and the saddle, so the nut is out of the picture altogether. Same thing with a capo. Hmmmm. So could it be that the breaking angle of the string over the bridge is going to have more to do with
In theory, a string should contact only one point at each end, and if that one tangent point could be infinitely small, the string would vibrate most freely and accurately. However, a razor-sharp end point would be difficult to achieve, plus it would snag the strings between windings, or even slice through the string and cause a whole new batch of problems. A practical trade-off is to have a small contact point without being ridiculous.
Is there an ideal downward angle? In a physics equation, yes. It would be one where the string passes over a tangent point at a 90-degree angle so that all tension from the tuning machine would pull the string down onto that one point. As usual, real life is more complicated because a string is not infinitely thin, nor frictionless, nor is that break point (the nut) infinitely small. Strings have thickness, and if you try bending them at too steep of an angle, then the windings cause them to hang up on the tangent point. Bummer. So, you have to work out a breaking angle that doesn’t cause the string to hang up. Some wise inventors have come up with roller nuts, nuts made of low-friction material, and great lubricants, all designed to cut down on the "drag and snag" at the nut. Floyd Rose’s clamp took another route: no downward angle at all, since the string was fastened at the nut.
Which brings us to a real troublemaker: the tremolo. The idea is to rock back and forth and either increase or decrease string tension. If you push the bar down hard, you'll see the strings slacken considerably. Many times a string–particularly a wound on–is pulled a bit toward the nut, and it "hangs up" (sticks) in the nut slot. Sometimes you hear a ping, but sometimes you hear nothing. . . until you're playing, and then it pings and goes out of tune as the string tries pulling itself so that its tension is equalized on both sides of the nut. Again, Floyd’s clamp took care of that at both ends, with strings clamped at the nut and at the bridge. Hard to change strings, but the problem of string slippage over nut or saddle disappeared. Some might argue that it also cut down on sustain, but I didn’t detect too much sustain missing from Steve Vai or Alex Lifeson’s guitars in the 1980s.
So, what does a steep angle offer? Among other things, it ensures that, under most circumstances, the strings will stay in their slots when you bend them. If you've ever had an improperly cut nut where your low or high E string pops out from time to time, you know what kind of trouble it is. And a reasonable breaking angle will, indeed, contribute some sustain. Determining what is the best string angle is still a matter of personal choice on the part of a guitar’s designer.
What about string trees, you ask? They help to keep the strings from popping out of the nut’s slots. If they’re improperly designed and produce too much friction, they introduce more tuning problems. Rollers and graphite-impregnated string trees take care of a lot of that. Does more sustain result from having string trees? Hard to tell. Again, it all depends on the overall guitar. And if your amp is loud and close to your guitar, it’s going to sing like a bird no matter what the breaking angle is.
Another point, this one having to do with construction: In most cases, to achieve a steep downward angle, a headstock is grafted onto the neck. A big reason is to make it cost-effective, since a single-piece neck/headstock with a steep angle would require generating a tremendous amount of wasted wood when carving from a single, thick, wide piece of wood. Is a graft cause for concern? Not usually. In fact, a properly glued graft is often stronger than the wood on both sides of the joint. However, a poor graft design or weak joint can be the place where there's a break if the instrument ever hits the floor headstock-first.
Bottom line? Well, when it comes down to it, you have to be the final judge. Listen to the guitar as a system. Listen to your guitar and amp as a system. Listen to everything between your fingers and your ears as part of the system, too. Then decide how steep that downward angle has to be.