Friday, September 18, 2009

Black Keys /Accidentals in C

There are seven tones in the key of C (as there are in all 12 keys), these are the natural tones. And since there are twelve tones in the entire system, five tones remain. The black keys of the piano are those five tones not belonging to the key of C. These tones are the sharps or flats; C#/Db - D#/Eb - F#/Gb - G#/Ab - A#/Bb. On the guitar these same five tones are aligned at the 11th fret and also distributed across the fretboard in the symmetrical system we've been mapping out in this blog. These 'black-key tones' are also known as the accidentals in the key of C.

The natural tones align in three axis positions on the fretboard between the open strings and the 12th fret; the Phrygian Axis at the open strings (and 12th fret), the Aeolian Axis at the 5th fret, and the Dorian Axis at the 10th fret (see 'What is Fretography'). But there is one more axis; the axis formed at the 11th fret by the alignment of the 'black-key tones.'

Naming this axis is not so simple. We could call it the Black Key Axis, or the Sharp and Flat Axis, or the Accidental Axis But it would be better to use a term that is more in keeping with the names we've assigned the other three axes, which are each based on a Diatonic Mode.

Taken as a group, the five black-key tones can be described as the 5 flats of the key of Db, which is the first of three keys which incudes these tones; Bb, Eb, Ab, Db, Gb (with C and F remaining to complete the key). The two other keys which include these tones are: Gb - has all five plus the addition of Cb (which is enharmonic with B), and the key of Cb - all 7 tones are flats.

The black keys can also be thought of as C#, D#, F#, G# and A#. which can in turn be found in three keys which are enharmonic with the three flat keys we've just described; B (enharmonic of Cb), C# (enharmonic of Db), and F#(enharmonic of Eb).

We'll use the key Gb as the context for this Axis because it comports with the symmetry principle better than F#. In doing so we are choosing a key signature which is a b5 above C, as opposed to F# which is an augmented 4th above C. Theoretically, a flat 5 trumps a sharp 4. Thinking of it as the Secondary Aeolian Axis places it at the center of another layer of symmetry, as we shall see in the next blog post.

In Fretography we the Axis of tones not belonging to the key in which we are working as the Void Axis. The Secondary Aeolian Axis of the key of C is simply the Aeolian Axis in the context of the key of Gb. In C, it is the only fret position made up entirely of tones outside the key. In Gb it is at the center of the diatonic symmetry. Each key, then, contains a Secondary Aeolian (or Void) Axis on the fretboard based on the position between its Dorian and Phrygian Axes.

In music theory there is always more than one way to describe a given concept. For example, The 'Major Scale' is also known as the 'Ionian Mode.' The tones of an A minor 7th chord can also be described as an inversion of a C 6th chord. It all depends on context. For that reason, some structures in Fretography can have more than one name.


The five black-key tones also comprise a pentatonic scale based on the same interval structure as that typically used in rock and blues. If you're familiar with pentatonic scales on the guitar, play the black-key tones shown on the diagram above and you'll recognize the patterns.

But pentatonic scales are not just for playing rock and blues, and the black-keys needn't only be seen in the context of pentatonic scales. As important as it is to know where the natural tones are, it's equally useful to know where they are not. The pattern of black-key tones, studied in their natural context as sharps and flats, will enhance your fretboard comprehension.

We'll look at more theoretical possibilities for the black-key tones in the next post.

The diagram above shows all the positions of the black-key tones, and also includes Cb and F (in gray) which complete the key of Gb.

All contents of this blog are © Mark Newstetter

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