Inharmonicity, string gauge choice and playing up the neck
Posted: Wed Jan 18, 2017 9:18 am
So a random internet search frenzy prompted by questions on baritone guitar string gauges got me to a brand new subject, for me at least - inharmonicity. It's even hard to spell...
So the concept is that some plucked string instruments, like guitar, can have a string choice for a given note that has it's harmonics mostly closely in tune, or dramatically out of tune. I think the way it works is that a stiffer, heavier gauge string with higher tension will have greater inharmonicity for a given note. I found this quote on this page: http://www.acs.psu.edu/drussell/Demos/S ... ess-B.html
"For a long, thin string (like the E4 string fretted at the nut on the headstock) the inharmonicity is negligible, and the frequencies are almost exactly harmonic (at least as far as the stiffness effects are concerned). For a long thick string, (the low E2 string fretted at the nut on the headstock) the inharmonicity is noticeable for the higher harmonics, but not very noticeable for the lowest frequencies. However, for short, thick string (the low E2 string fretted near the sound hole) the stiffness effects are quite large, and the inharmonicity is easily noticeable even for the first few harmonics."
I found this fascinating, because it solves a conundrum that I have had ever since I built my archtop last year. I first strung it up with what I had in the shop at the time, which were .011 - .050 nickel strings and really liked the sound. I bought into the idea that I had to use medium gauge strings on it, and put them on and hated the sound. It sounded dead and thuddy, got better with light gauge strings, got better again with .012 - .056 tuned down a full tone, in fact it really came to life at that point, and I had no idea why. I also always wondered why an E3 or a G3 played on the sixth string sounded so different compared to the same note played on the fourth or third string. Dull and thuddy compared to vibrant and alive. The idea would seem to be that by reducing the gauge of the string and lowering it's tension you can reduce the inharmonicity, particularly when playing up the neck. I would really love to hear what other people think of this idea.
Edit: Particularly on the idea of scale length relative to inherent inharmonicity (it's still hard to spell). Would a longer scale - say 25.6" compared to 25" - yield less inharmonicity and sound better played up the neck, if string gauges were chosen for the same tension with both scale lengths?
Brian
So the concept is that some plucked string instruments, like guitar, can have a string choice for a given note that has it's harmonics mostly closely in tune, or dramatically out of tune. I think the way it works is that a stiffer, heavier gauge string with higher tension will have greater inharmonicity for a given note. I found this quote on this page: http://www.acs.psu.edu/drussell/Demos/S ... ess-B.html
"For a long, thin string (like the E4 string fretted at the nut on the headstock) the inharmonicity is negligible, and the frequencies are almost exactly harmonic (at least as far as the stiffness effects are concerned). For a long thick string, (the low E2 string fretted at the nut on the headstock) the inharmonicity is noticeable for the higher harmonics, but not very noticeable for the lowest frequencies. However, for short, thick string (the low E2 string fretted near the sound hole) the stiffness effects are quite large, and the inharmonicity is easily noticeable even for the first few harmonics."
I found this fascinating, because it solves a conundrum that I have had ever since I built my archtop last year. I first strung it up with what I had in the shop at the time, which were .011 - .050 nickel strings and really liked the sound. I bought into the idea that I had to use medium gauge strings on it, and put them on and hated the sound. It sounded dead and thuddy, got better with light gauge strings, got better again with .012 - .056 tuned down a full tone, in fact it really came to life at that point, and I had no idea why. I also always wondered why an E3 or a G3 played on the sixth string sounded so different compared to the same note played on the fourth or third string. Dull and thuddy compared to vibrant and alive. The idea would seem to be that by reducing the gauge of the string and lowering it's tension you can reduce the inharmonicity, particularly when playing up the neck. I would really love to hear what other people think of this idea.
Edit: Particularly on the idea of scale length relative to inherent inharmonicity (it's still hard to spell). Would a longer scale - say 25.6" compared to 25" - yield less inharmonicity and sound better played up the neck, if string gauges were chosen for the same tension with both scale lengths?
Brian