Nut width is the most subtle factor. The two most common widths at the nut on the vast majority of acoustic guitars sold these days at 1 11/16” and 1 ¾”. You would thing that a difference of only 1/16” wouldn’t make all that much difference but it certainly does. For well over 100 years, Martin guitars were made with the narrower 1 11/16” nut width, and many still are. If you have fairly thin or average width fingers, that’s just fine, and even someone with wider fingers can adjust their technique somewhat (i.e., being sure to arch those fingers and use the tips only) and get clear, clean tone from every string. But especially men with wide fingers and poor technique will struggle with a guitar that has a nut width of 1 11/16”.
Bob Taylor of Taylor Guitars recognized this early on and after building guitars for the first few years with Martin’s standard width he went to 1 ¾” on the vast majority of his fine instruments. That, combined with a thin overall neck profile was an instant hit, especially with younger players who may have come from an electric guitar background. Martin took note and before long they were producing more and more guitars with 1 ¾” nuts and about a decade ago they introduced their Performance Profile neck, which is almost identical in every way to Taylors width and profile. It did and continues to get mixed reviews from players; personally, I like it to a degree but being cursed with fairly short (but thankfully, narrow) fingers I find Martins with that neck profile to be very fatiguing to play for very long.
This brings up another factor, which is playing the dreaded barre chords that every guitarist MUST conquer if he or she is going to progress beyond the beginner level. The wider the neck, the more difficult it is for most of us to play barre chords. I’ve written before about correct technique when playing those damned things (dropping the wrist and fore arm, compared to 1st postion “open” chords; locating the pad of the thumb directly behind the neck and beneath the barring finger) and the truth is that applying that correct technique is a more radical move when you’re moving from open to barre chords. It can be done of course, and most players with guitars with a 1 ¾” nut learn to do it, but it adds a bit more difficulty to the learning curve.
If you doubt this, look at the classic Gibson arch tops used by jazz players, who almost always play partial or complete barre chords. Those guitars almost always are made with 1 11/16” nuts. Taken a set further, look at Fender and Gretsch electrics – they go even narrower, with 1 5/8” nuts.
Speaking of Gibson, most of their classic acoustics such as the J-series are made with what can be called a “compromise” nut width, measuring 1 23/32”. Gibson also slightly rounds the edge of the fretboard, and combined with a “soft –C” neck profile this makes for a very comfortable neck. In recent years I have come to really like the necks on Gibsons! I can play both open chords and barre chords up the neck with ease, assuming the action and neck angle have been tweaked to my liking, which is usually necessary with off-the-shelf new Gibson acoustics.
Twelve string guitars must have a wide neck, usually about 1 7/8” or even 2” to account for all those extra strings. As you can imagine, trying to play full barre chords on a 12-string is not an easy thing!
Nylon string guitars have much wider necks, sometimes measuring 2” or even more. The exceptions are the modern acoustic/electric “crossover” nylon string instruments that usually measure somewhere close to 1 7/8” at the nut. These are designed for players who most likely are coming from a steel-string background and just can’t abide with the wide necks of a traditional classical guitar. Their relative merit is a separate discussion.
So what’s right for you? Obviously, playing as many guitars as possible is the only way to know for sure. Many of the better imported guitars such are coming through with 1 ¾” nuts but some companies such as Yamaha continue to produce the majority of their guitars with the 1 11/16” nuts. The take-away here is to be sure to avoid judging the comfort of a guitar neck by “action” alone. Consider the width of your fingers too!
Peace & good music,