Long scale vs. short scale bass guitar fret lengths?
The distance between the frets on a long scale bass guitar are slightly longer than a short scale's distance between frets, yet the same notes are produced on the same frets on both guitars. Why? What's they theory behind this? Intuitively, it makes sense that there would be a linear change in notes based on how far you slide your finger up the fretboard. But if that was the case, eventually the notes would be different on both guitars based on the length you've moved on the neck. However, they're not different. Why?
- Me2Lv 74 weeks ago
"Intuitively, it makes sense that there would be a linear change in notes based on how far you slide your finger up the fretboard." No it doesn't, because the relationship is not linear, as is obvious from the decreasing fret spacing going up the fretboard.
A string fretted at the midpoint — the 12th fret, and coincidentally about 12 inches up on a guitar neck — has half the vibrating length of the open string, oscillates at twice the rate, and produces the note an octave above. At the 24th fret, only six inches higher, the vibrating length is reduced to one-quarter. oscillation is quadrupled, and the pitch is two octaves above the open string.
Consider an electric guitar D (4th) string. To sound an octave lower, the string length must be doubled to about 50 inches, which is completely impractical. Even the very largest orchestral basses top out at about 43 inches.
Therefore, the electric bass scale length is only moderately increased by about a third, and the string masses are increased, but much greater than you might expect. All things being equal, the lower-pitched string would have a much wider oscillation, therefore it must be under higher tension — at least about double — to allow reasonable action and dynamic range without fret noise. For equal lengths, the bass string may have five times or greater than the mass of the guitar string pitched an octave higher.
- TommymcLv 74 weeks ago
The distance between frets is based on ratios, fractions of the entire vibrating length of the string. Look at it this way: we know that the mid-point of a string will always be an octave. That's just part of the physics of a vibrating string. So fret 12 must be at the midpoint between the nut and bridge. On a 34" scale bass, the octave (fret 12) will be roughly 17 inches up from the nut. On a 31" bass, that same octave mid-point has to be 15.5 inches up from the nut. So it's *proportional* distance, not absolute distance that determines the octaves....and all the notes in between.
The note (pitch) that a string produces is also determined by the gauge and tension of the string. A long scale bass needs a little more string tension to produce the same note as a short scale bass, using the same gauge strings. So even though the open strings on a long scale and short scale bass are tuned to the same notes, they are under different tension from each other. So you really can't compare distances up the neck because there are other variables that aren't equal.
Taking this a bit farther than bass, other stringed instruments use the same ratios for placement of the frets. Guitar, mandolin, ukulele, banjo, etc. They all have different scale lengths, but have the same proportional distance between frets. If you're curious about the exact computation, here is an explanation: https://www.liutaiomottola.com/formulae/fret.htm