The concept of the multi-scale musical instrument (one in which each string has its own scale length) is not new by any means. It is commonly employed in many instruments such as the piano, harp, and others. This multi-scale arrangement applied to a fretted instrument has become known today as “Fanned Frets” or simply “Fan Frets”. It first appeared on the 16th century Orpharion, a variant of the cittern, as well as the Bandora which is a late 16th century instrument with a longer string length for its bass strings than for its trebles.
The Importance of Scale Length
The scale length (or distance measured from the nut to the saddle; the vibrating length of the string) of any musical instrument is probably the most commonly overlooked element of design when engineering the “voice” or “tone” of a guitar. The scale length is responsible for regulating the initial input of vibration energy that is injected into the guitar’s top setting the entire system in motion. Everything after that point can only be filtered or somehow modified, but not added to in any large way. While the myriad of components and other variables of the individual guitar will play a large roll in determining its voice, the scale length will still set the main parameters that the rest of the system will have to work within.
The Effect of Scale Length On Guitar Tone
One of the best illustrations I have heard regarding the critical influence that the scale length has on guitar tone is from Ralph Novax, the father of the modern fan fret resurgence. He described this in his Fan Fret Technical Lecture as follows:
“The familiar example might be the “Strat vs. Les Paul” comparison: as stock instruments they have distinctly different voices. We could put the Les Paul pickups in the Strat and vice-versa, then take the screws out of the Strat neck and glue it in, and break out the Les Paul neck and screw it back in. Voila! The Strat still maintains much of its clear, cutting quality, although a bit “fatter,” and the Les Paul still has a round attack and mushy bass, although “thinner.” We’ve discovered that the pickups and construction can’t override the tonal effects of scale length. The upper partials present in the harmonic structure of the longer scale Strat string tone give it a cutting clarity that distinguish it from the sweet, round, lower partials that dominate the shorter scale Les Paul string tone.”
Other Factors To Consider
So now that we know the importance of scale length, there are still other factors that we have to think about, which are at play in tandem with the scale length to give the guitar its basic tonal or harmonic envelope. Those factors are: string tension and mass.
Without getting into the mathematics of it (see this link for further reading) the basic premise is that each time we increase the diameter of the string, thus increasing its mass, we also increase the amount of tension required to bring it to pitch. This is why players most often use larger gauge strings for the lower notes of the guitar. If we used the same high E string for the low E, I’m sure you could imagine, it would not sound too good. It wouldn’t have enough tension to sound in the overtone series and it also wouldn’t have enough mass to give it any volume. So having more mass (larger diameter) is better for a string tuned to a lower pitch, but we also have to keep in mind that this added mass and tension brings with it two side effects. The first is that the extra mass helps the string get more volume and clarity, but the second side effect is increased stiffness. As the stiffness is increased, the strings ability to divide into complex high frequency nodes decreases.
Understanding The Effects Of String Stiffness
My good friend and mentor luthier Gila Eban, explained something like this to me years ago by using the analogy of a dish cloth. If you start with a regular dish cloth and fold it in half, it’s very easy and folds nicely. Fold it again and it is still OK, continue folding in half again and again and each time it becomes in effect thicker. With that extra thickness its ability to fold gets diminished and requires more energy or simply isn’t possible to fold again. This type of folding is akin to a string as it “folds”, or divides, into smaller and smaller sections that make up the overtone series of the strings fundamental note and give the note its tonal and harmonic character.
The Single Scale Problem
The problem is that we usually have six strings each with a different set of the above mentioned criteria. Using only one scale length causes us to compromise overall. Lets say I decide that for my new customer the best scale length to get the sound he wants for a steel string high E might be 25″, but he also wants to tune down to a dropped D on the low E string. That D will sound floppy and muddy at 25″ (with a standard gauge string). OK, no problem, lets use a 26″ scale then and the dropped D will be great; but now at 26″ the high E sounds like a banjo and could possibly shatter a wine glass or something with its shrill piercing voice. This is where the fanned fret (multi-scale) type of guitar comes to the rescue.
The Fan Fret Solution
If we use a fanned fret system, we can specifically choose a different scale for each string that perfectly suits our needs and allows us to incorporate all of the necessary criteria we have without compromising on any of the strings. We can get that great mellow treble at 25″ AND that clear powerful bass note at 26″.
“But what about playing the thing…, is it really comfortable to play those fanned fret guitars?” Yes, it is actually more ergonomic than playing a standard single scale instrument! Look down at your hand and spread your fingers as wide as you can. Do you notice how your fingers are actually fanned out, emanating from a common point? This resembles the angles on a well thought out and implemented fanned fret guitar fingerboard and in most cases requires less of that awkward wrist tweaking we guitar players all hate as we strain to make our “fanned fingers” go in parallel lines perpendicular to the strings like a traditional single scale fingerboard.
OK, don’t get me wrong, I still love my traditional single scale guitars, they are wonderful instruments in their own right and for most people they are the way to go, but for you adventurous thrill seekers who just want to push the limits in harmonic complexity and power on your guitar even further than on your standard guitars, then the fanned fret system is definitely something to consider on your next handmade guitar.
If you have any other questions, comments, or other thoughts, leave a comment below or send me an email, I would love to hear from you!
This entry was posted on Thursday, October 6th, 2011 at 1:29 pm
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