Intonation and the Scale of Things
The guitar is by default never in tune. This can create immense frustration with players who can’t stand to have their guitar to not be in tune. I know players who even tune during a song. Modern technique can, unfortunately, only help you so far. The ‘Robot Tuners’ that were introduced a couple of years ago can tune relatively fast and are a major aid for many players, but the moment you start using those tuners with a vibrato bridge, you’re in trouble because the bridge will move whenever one string’s tension is changed. In this article I’ll explore the reason why a guitar is never in tune and what the industry developed to fight the problem. I also want to take a closer look at scale lengths.
Why are frets actually necessary?
The distance of a vibrating string coupled with the tension creates its unique, specific pitch. To find the balance between making the guitar as easy to build as possible and having it in tune as well as possible, we have the frets. These little metal bars have different distances between them. No two distances are the same, but the distance between two frets are the same for each string. This is to make sure the frets are easy to replace, level and dress. But because the strings of a guitar aren’t of equal thickness, you get different points of intonation. That means the point of contact of each string is different from the other. That’s why you need to intonate at the bridge, and you can only intonate it with respect to another fixed, measurable point.
Most guitars are intonated with respect to the 12th fret and the harmonic overtone of the 12th fret. This offers the best compromise between intonation higher and lower on the neck. But what if you want it to be perfect? Each string intonated at each fret perfectly?
The company Fretwave (pictured is True Temperament) came up with a unique fretboard design. Essentially, they have a fret for each string, with a unique distance between each fret, per string! This ensures an intonation as close to perfect as possible. The downside is unfortunately obvious: leveling the frets is still the same job, but crowning (achieving the roundness and smoothness of the fret after leveling) is horrible! Instead of doing it in one sweepy action of the crowning file (a specialized file with a crescent shaped edge), you have to crown each fret for each string individually! The unique thing about these frets though – besides perfect intonation – is that the technique of bending remains the same. As a player, you don’t feel a difference.
A less obtrusive way to get a better intonation is to have a specialized nut. Some companies offer compensated nuts. These are made in a way that the point where the string leaves the nut isn’t uniform, but, again compensates slightly for each string. These systems are clearly less perfect than having each string intonated at each fret, but this is a very fine alternative.
How do the frets relate to the scale of your guitar?
The distance between the frets can be arrived at through a series of calculations, and those distances are a result of the scale. The scale means the length of the piece of string that can vibrate (I.e.: the distance between bridge and nut). Some guitars use rather long scales (such as a baritone, or to a lesser degree, Strats and Teles). Others use a shorter scales (most Gibson solidbody guitars) and others are even shorter (such as Fender’s Mustang or Jaguar guitars). They range from 28.5″ to 24 inch”. Longer scales can have a higher tension on the strings, making the feel tighter. For a baritone the reasoning is obvious: if you have your lowest string tuned to a B or maybe even lower, you don’t want your string to flap around making your sound mushy and woofy: you want it to sound tight, and a higher string tension can be extremely beneficial in that respect.
A relatively new trend is to use something called ‘fanned frets’. These guitars have a lower scale on the higher strings and have their scale gradually increased towards the lower strings. These systems use one central point of reference; from that point on the frets start to fan ‘outward’ and ‘inward’. The intonation issues found on ‘conventional’ guitars still persist in these kind of instruments; the frets are just ‘fanned’ in order to get the longer (tighter feeling) scale on the lower strings and get a shorter scale (easier, mellower feel) on the higher strings. Fanning your frets is unfortunately a procedure that has to begin at the early design and build stages of the instrument; you can’t (easily) retrofit a guitar to have this system. That would entail removing the old fretboard, repositioning the bridge and nut and placing a brand new fretboard. Clearly not a viable retrofit-option! But for the adventurous guitar player, there are always luthiers willing to fan the frets, and their numbers are growing. It simply offers a unique look and feel, and may broaden your tonal and technical possibilities!