Many guitar players believe that you're not really serious about guitar playing until you buy custom
made instruments from a luthier, or even build your own guitar. That may be true, but for me and my
kind of music, an off-the-shelf
Guild or Martin or Taylor is just right. There is only one thing about buying off-the-rack acoustic
steel string guitars that really, really sucks, and that's the setup, or rather, the lack of it.
By guitar setup, I mean what many people refer to as the action of the guitar. Generally speaking, the action refers to the size of the gaps between the strings and the frets. Most people are aware of two variables that they can tweak to set the action: the saddle height and the curvature of the neck, the latter commonly being referred to as the neck relief. Typically, people adjust the saddle height so that the gap between the strings and the twelfth fret is some value that they like, and they set the neck relief so that when a string is depressed at the first and the fourteenth fret, there remains a very small gap between the string and the sixth fret, about the thickness of a business card.
Somewhat surprisingly, not too many people pay attention to the fact that rather obviously, the strings rest not only on the saddle, but also at the opposite end in the slots of the string nut, and therefore, the depth of these slots is a a third variable that affects the size of the gap between the strings and the frets. As a matter of fact, the effect that the slot depth at the nut has on the playability of the guitar is dramatic. Suppose first that the slots were very deep, so that the gap between the strings and the first fret became very small. Then an open, unfretted string would buzz on the first fret. You have probably never experienced that, certainly not on a new guitar. You know why? Because on a new guitar that comes off the shelf and not from a luthier, you almost always have the opposite: the slots in the string nuts are not nearly deep enough, resulting in a larger-than-necessary gap between the string and the first fret.
Now imagine your index finger when you're fretting the C chord, and suppose the slot for the B string is not very deep, so that the B string is high above the first fret, like this:
It's not hard to guess what the effect of that will be: it's going to be very
rough on your fingertip, because it takes a lot of force to bring down the string so close to the nut.
In addition, the deep and sharp depression of the string will increase the pitch
of the string a lot. That will result in poor intonation, that is, your chords are
going to be way off even if your tuning was perfect.
Ok, there you have it: for a perfect setup of your guitar, you'll have to adjust the neck relief, the saddle height, and the slots in the string nut. Your goal, of course, is to get the smallest gap between any string and any fret without getting string buzz.
Performing the setup is not very hard and requires only the most basic tools and skills. There will of course be a lot of trial and error, and a bunch of saddles and perhaps even string nuts will end up in the recycling bin. But if you hang in there, you will quite likely be rewarded with a noticeable difference in the playability and intonation of your guitar.
Before we proceed, though, I would like to bring to your attention Bryan Kimsey's website. Bryan has done more systematic research on the subject of steel string guitar setup than anybody else that I know of, and he has put a lot of effort into explaining his findings. My own final conclusions are a bit different from his. But I didn't even have any final conclusions until I studied his work.