One of the dark secrets of the guitar: guitars don't play perfectly in tune. Actually, all fixed tuning instruments, such as piano, play slightly out of tune.
It is impossible to place the frets on the guitar so that all notes on the instrument will be perfectly in tune in every key -- simply impossible, because of the way tuning works.
There are two basic types of tuning in western music: Pythagorean and tempered. Pythagorean tuning is named after the mathematician who created all those theorems that taunted us in high-school math classes. He discovered the mathematical principles of intonation, such as a pitch whose frequency is twice as high as another pitch is one octave higher. His principles explain mathematically the perfect tuning for each step in the octave.
The problem with Pythagorean tuning is that it works only within one key. In other words, if you tune all the notes on a piano so that the notes are perfectly in tune in the key of C, they will be out of tune when playing in other keys.
Intonation used to cause many problems. For example, in the olden days, when a lute player needed to play a piece in another key, he had to actually move the frets on his lute (lute frets were made of gut for just this reason). Some harpsichordists actually retuned their strings to switch keys.
So, to handle this, a tuning system called "tempered tuning" was developed (maybe it was named after a harpsichordist who got really mad from having to constantly retune). Tempered tuning places all the notes at a slightly compromised frequency to yield good, but not perfect, tuning in all keys.
Tempered tuning applies to guitars as well. The frets on a guitar neck are laid at specific positions to yield a good compromise in tuning, but a guitar can not possibly play perfectly in tune in all keys.
How Should I Tune?
The easiest way to tune is with an electronic tuner, but I think that everyone who plays the guitar should be able to tune it without an electronic tuner.
The quickest way I have found to tune the guitar without a tuner is what I call "Kings Island tuning", so named because many years ago I played guitar at an amusement park named Kings Island, and frequently found myself with just a few seconds to tune up before the show.
I tune the top E string to the reference pitch (from a tuning fork, or piano), then tune each string to the top E string as follows:
B - 5th fret to open E
G - open string to 3 fret G
D - 2nd fret E to open E
A - Open A to open E (listen for beats in the perfect 5th - check against open B string too)
E - Harmonic 12 fret E to open E
You can quickly get the guitar very close to in tune with this method, then, if need be, make minor adjustments.
Tuning all of the strings to one string eliminates the potential for the passing small variations in tuning from string to string, by tuning 1 to 2, 2 to 3, 3 to 4, 4 to 5 and 5 to 6.
Remember that game you played as a kid in school where one kid whispered the phrase "My dog is named Jake" to the next kid, and it is passed from kid to kid in the room, and when it gets around to the last kid, it has turned into "A big swollen refrigerator"? The same thing can happen with tuning. Small mistakes are passed from string to string, and can cause problems. That's why tuning all the strings to one string is so effective.
Do Harmonics Work for Tuning?
You will often see a player tuning by playing the 5th and 7th fret harmonics from adjacent strings, and then making those notes match. This method is not a good way of tuning the guitar.
The 7th fret harmonic is a Pythagorean 5th. The guitar fret at the 7th fret is an equal tempered 5th. If you tune by matching the harmonic at the 7th fret, you will be guaranteed to be putting the string slightly out of tune with your frets.
On the other hand, the octave harmonics at the 12th and the 5th frets can be safely used for tuning.
© 2002 - 2016, Tim Berens