Why does the B string on the guitar sound a bit out of tune?
A common problem people run into when playing guitar is that sometimes the B string doesn’t sound that great even though it’s perfectly tuned. In other words, if you tune the B string perfectly to the G string, the B string will sound a bit out of tune with the other four strings. How come?
Briefly explained, the reason why the B string always sounds a bit out of tune is that in the West we use a 12-tone tuning system, which is not 100% consistent with the way sound is measured in Hertz by the laws of physics.
If we walk across the fretboard of the guitar from bottom to top, there are 12 steps to get to the same note an octave higher. The notes that make up tuning system in Western music are divided into 12 different tones per octave. Technically, this system is “unnatural”, and that is because it does not equal the exact speed of the vibrations, measured in hertz, that make up the sound of each note.
Let’s look at the relationship between the six strings. You will see that the guitar strings, with the exception of the B string, are the same distance apart. Below are the tunings of each string on the guitar, measured in hertz.
In physics, every tone must be a multiple of the same tone an octave higher or lower. The only tone without a comma is the A. The A string on a guitar is 110 Hertz, one octave higher it is 220, etc. If we divide the values of the E string indicated above, it comes down to a factor of 4 .
But if we start designing the guitar based on hertz, then we get an unplayable instrument (see photo below). That is why (in Europe) the 12-tone scale has been used.
Example of a microtonal guitar. (This guitar was not built by Homestead)
The fact that a twelve-tone system does not fully correspond to the sounds of nature does not explain why it is mainly the B string that intones.
This is because the distance between the B string differs from that of the other strings. All the other strings are separated by four notes. E to A, are five semitones apart, just like A to D and D to G, but here’s the thing: from G to B there are only four semitones away from each other. Finally, the B to E strings are again five steps apart.
But why does distance determine voice clarity? That’s because the mathematical ratio of frequencies that the human ear interprets to represent a pure scale creates a slightly smaller interval than the scale needed to play the music.
At a distance of a quarter (5 notes) this is actually inaudible to the human ear. But with the shorter (four) distance from G to B this is audible. The deviating distance is therefore the reason why the B string sounds out of tune. Because the G string and B string are closer together, the inaccuracy in Hertz is up to 14%. As a result, if you tune the B string so that it sounds clean along with the G string, you will run into problems in conjunction with the other strings. Conversely, if you tune the B string with a tuner, it will sound too high in the ear compared to the G string.
In other words:
- The B string in perfect harmony with the G string: B string sounds too low compared to other strings
- The B string tuned to 247 Hertz: B string sounds too high compared to the G string.
For this reason, there are guitarists who deliberately detune the B string a little bit (tuning by ear). We also see bridge saddles with a recess for the B string or for the G and B string together (photo). That has somewhat the same effect.
It is all quite difficult to understand, but in summary we can say that the tones on a guitar do not correspond 100% to the sound according to the laws of physics (measured in hertz). This is usually inaudible, with the exception of the B string (in relation to the G string). Because this distance is shorter than the “perfect quarter”, the inaccuracy becomes greater. Most guitarists can live with this. Other solutions are: tuning the B string by ear, getting a modified bridge saddle (does not solve the problem completely) or buying a guitar with different frets.
We at Homestead, like 99.9% of guitarists, can live with the slight unevenness in the guitar’s scale. But we thought it would be interesting to explain why the B string often sounds a bit out of tune.