Multiple scale length instruments
I've wanted to introduce the idea of 'fanned frets' into my instruments for a long time, and as that time is finally upon me I thought it's worth making a blog post about.
So what does it mean? Well, the vibrating length of a guitar string (the ’scale length’) is normally the same for all the strings on most guitars. As a result the frets are perpendicular to the strings, and this makes for a nice and straightforward looking instrument.
A multiple scale length guitar - or ‘fanned fret’ guitar - uses a longer scale length for the lower/thicker strings, and a shorter scale length for the higher/thinner strings. This normally means that the nut and bridge are at angles pointing away from their usual positions. As a result, the frets fan out because the positions of the notes along each string are no longer in the same place.
It’s not a new idea - check out the ‘Orpharion’, a kind of lute invented in England in the 16th century:
The idea is similar to the difference between a grand piano and an upright piano.
Many people assume that fanned frets have something to do with solving intonation and general tuning problems, but I don’t really see a reason why that would be true. Intonation issues are normally caused by the amount that a string bends around a fret (worse for thinner strings than thicker strings) and this system doesn’t address that problem. It’s also not about creating some kind of compensation - that would still be done in the same way as a regular guitar (i.e. at the bridge end).
Fanned fret instruments are more about a change in the tone of the instrument. Most people notice that bass guitars and double basses are much longer than regular guitars. If you can imagine trying to tune a guitar’s low E string down to the pitch of the low E on a double bass, you’d soon find that the string is so slack that it won’t sound the note properly, if at all.
How do you solve this? Well - the variables involved in changing string tension for a fixed pitch are:
1) Scale length
2) String material
3) String thickness
Often, it’s only the string thickness that can only be changed. That’s why you sometimes see sets of strings specifically for ‘DADGAD’ or other low tension tunings. But that's just the start: many people go to C on the low E string (Martin Carthy-style folk fingerpickers in particular), and sometimes even B (looking at you, heavy metal fans). You’d probably find that the lowest string and top two strings are slightly thicker than your usual sets, or may be made of a different material favourable to lower pitches.
However, you can also make the length of the string longer if you want to reach lower notes. This way you can use your ordinary strings and take them to the same tension as normal but play in drop D, for example.
But Alex (I hear you ask) what’s the advantage of multiple scale length guitars if you play in standard tuning? Well - what this is what I’m excited about. It allows for the use of different gauge strings, and therefore a different tone. The low strings would be longer, and therefore ordinary strings will be higher tension. This will hopefully get around the problem that many guitars have in producing strong bass tones. In contrast, by having a shorter scale length for the higher strings the guitar is able to replicate the sweet tone that is often associated with shorter instruments, like parlour guitars and 12-fret Martin style instruments. All in one package!
So here’s a photo of my latest experiment, a multiple scale length gypsy jazz guitar. It’s still early stages but I’m already excited to hear the results. You can see the start of the fanning where the bridge is going to be - there is a faint crease in the soundboard (known as the 'pliage') above which the bridge will set.
Computers are also handy for crunching the numbers:
I’ll have to settle on the kind of string gauges I want to use soon, so that I can get the strength of the bracing right.
If you have any theories about how you think fanned frets might affect the sound please leave some comments below, I’d love to hear your thoughts! Maybe you’ve got some interesting ideas of your own that you’d like to see tried out? I want to hear them…