The best single note on a guitar can be played with one hand. No matter which of the six open strings you prefer, they are each vastly superior to every other “fretted” E, A, D, G, B, or E (assuming standard tuning). There’s simply more going on. When you fret a string, you choke it. Some of its vast potential overtone series is lost in translation (more on that later) The fact that fretting enables a guitarist to easily change keys while constructing vast, complex chord progressions makes up for this sacrifice of tonal purity, but why not have both?
Part I: Even Temperament and “Sweet Tuning”
Most “western” music is based on the principal of “even-temperament”, in which the piano is king. Even-temperament refers to the way an instrument divides an octave (C to C, G to G, “Do” back to “Do”, etcetera). On a piano, all the intervals are arranged in equal frequency ratios, but in nature, the distances between these notes aren’t quite so consistent. In earlier musical traditions the world over, “just intonation” was employed. This method of dividing the octave submits to natural, whole number frequency ratios to create it’s notes. It works great if you only play in one key, but modulation presents a problem. By embracing even temperament, guitarists are able to treat any note as the “root”, modulate, and play in every key; but have you ever felt like one of your strings (usually the B) sounded a little off?
Savvy guitarists have caught on to this through sheer musical intuition. “Sweet tuning” is an approach in which specific strings are tuned a little “off” from what a piano or electronic tuner would tell you is “in tune”. Of course, there is a huge amount of subjectivity involved, ranging from a guitarist’s attack (strings go a little sharp when struck hard) to the voicing of the instrument itself, but to my ears, the biggest culprit is usually the major third (that pesky B on the open second string when playing in the key G).
In terms of dividing an octave, the fifth and third scale degrees (“Mi” and “So” in Western solfége) are the most important because they occur early in the harmonic series created by the root note, or “fundamental”. Basically, we never actually hear just one note. Fundamental tones, the notes that we assign letters and numbers to, actually conceal vast tapestries of harmonic overtones that imbue a note with timbre and that mysterious, yet unmistakable quality of “in-tune-ness”. If you lightly dampen a struck string on the 7th fret, the Perfect fifth of whatever the open string is tuned will be revealed as a natural harmonic. Using this same technique, you can also unmask the Major third around the 4th fret. Only these intervals and the Octave itself (5th and 12th frets) are easily audible using this method. Natural harmonics extend exponentially (and reciprocally), but even trained ears can only detect so many. Within the vast universe of sound contained within an open string, the Octave, Major third, and Perfect fifth are the most transparent. To hear them ascend, strike the 12th, 7th, 5th, and 4th in succession. In part II we’ll discuss octave reduction and how to assemble a complete musical scale using overtones.
Now let’s put this knowledge into practice. In even temperament, the “Perfect” fifth is pretty close to where it should be (about 3:2), but the Major third is audibly a little sharp. Bearing this in mind, sweet tuning becomes more approachable. Take a G major chord, for example, one of the most popular triads employed on the guitar (G,B,D). For this experiment, fret it in the open (cowboy) position using only three fingers, leaving the second string open. This way you can really hear that imperfect major 3rd. Focus your ears on the open B string. Compare it with the overtonal Major 3rd of the G (third string open, buried around the 4th fret). Your ears aren’t lying. It sounds a little sharp. Now pitch that B on the second string down a few cents and enjoy the startling symmetry of a sweetened open G!
Now let’s say you’re playing in another very friendly guitar key: C Major. In this case, the guilty Major 3rd can be heard on the open first string (again, assuming a big, old “cowboy” voicing). Take your high E down a few semitones and savor the flavor.
Of course, you must always remain conscious of how these small changes will affect the rest of the chords in a given song or progression, but by learning to trust your ear rather than your tuner, your musicianship will surely improve. After all, our ears are basically antenna that have been perfectly designed to receive music. Spend enough time contemplating an open string and you will be guided towards its inner symmetries. In India, the “Do” (Tonic, Root, One,) is symbolized by the Peacock, because it alone holds all the other colors