Guitar Theory From First Principles, Part 4

In articles 1, 2 and 3 we started learning about the Fretboard, the Key (including the Major Scale, Intervals, Triads, Chord Scales and Chord Progressions), the CAGED system and the Modes (or Inversions). This month's lead guitar element focuses on using the major scale to build other scales e.g. Natural Minor, Spanish, Blues and Japanese Pentatonic scales. The rhythm guitar element remains CAGED, with the focus on 7th, 9th, 11th and 13th extensions.

The formula for a major scale is TTstTTTst (article 2) and this produces the following intervals: R 2 3 4 5 6 7 R (article 2). If we use C as the root we get R=C, 2=D, 3=E, 4=F, 5=G, 6=A, 7=B, R=C. Grab your fretboard to confirm and memorize a one octave shape for the scale building tasks ahead e.g.

The natural minor scale has the following interval structure: R 2 v3 4 5 v6 v7 R. If we compare this with the major scale (R 2 3 4 5 6 7 R) and apply the necessary flats we produce: C D Ev F G Av Bv C. Work out a shape, write it down and memorize e.g.

Now repeat with the following scales:

The Spanish scale = R v2 3 4 5 v6 v7 R = C Dv E F G Av Bv C

The Minor Blues Scale = R v3 4 v5 5 v7 R = C Ev F F# G Bv C

The Japanese Pentatonic = R 2 4 5 6 R = C D F G A C

In order to use these scales for improvisation you need to look at the triads the scale produces (indicated next to each scale diagram above). The C Japanese Pentatonic does not produce a complete tonic triad (it lacks a 3rd) but the presence of a v2nd and v6th suggests this scale will function well over a minor chord (v2, v3, v6, v7 are known as minor 2, 3, 6 and 7 intervals). If you have been working on the modes (article 3), then you will notice a similarity between the Spanish and Japanese Pentatonic scales and the Phrygian mode in terms of intervals. This is food for thought.

Now let us turn to matters rhythmic: The CAGED major chords can be extended by adding additional intervals from the major scale e.g. if the 7th, 9th, 11th and 13th notes of the C major scale are added into the C major chord in any order, interesting variations of the C chord arise. These extensions evoke different genres and scenarios e.g. I find that by adding the 7th (B) and 9th (D) into a major chord, the mellow smooth jazz vibe emerges. Once you get some shapes together, spend some timw internalizing the sound of each new chord and the constituent intervals (or voices) e.g.

Notice the G & E shapes omit a string each. Don't be shy to trim the fat so long as it sounds and feels right to do so.

Now take these shapes and covert them into movable bars. Convert them to C chords by moving them up the board as follows: A to fret 3, G to 8, E to 8 and D to 10.

Next generate a C major turnaround using the C chord scale (article 2) e.g. C F Em G (I IV iiim V) and repeat. Each time you return to the C chord use a different extension that you built. Listen to how each extension influences the vibe of the progression. Now try extending the remaining chords in the turnaround with any that please your ears (I will deal with naming experimental chords in greater detail later). Now fire up your looper pedal and jam over the chords with the C scale.

Figuring out the Cm chord scale needs to wait for next month but in the meantime try jamming over a Cm Dv Bv with the Spanish, Japanese and Blues scales.
My hope is by now that you have started to get an appetite for chord and scale building in the name of improvisation. If you fancy an exotic scalar dish, why not treat yourself to this hot and spicy C Indian Raga scale which reaches up into the second octave R 2 v3 4 5 v6 7 v9 before descending:

On the other hand perchance you hanker for a juicy altered dominant chord like this G# dom7 #5/#9 chord ( R 3 #5 v7 #9):

Finally, if you harness the Google with search terms like "exotic scales" (including parenthesis) then you will discover that the web is replete with nourishing formulae. Chords and chord theory are also a click away so dive right in and send me an email if you get stuck. If you can spare some cash I recommend you check out this superb chordal cookbook: "Chord Chemistry" by Ted Greene, Alfred Publishing Company (1981).

Next: The Harmonic Minor & Melodic Minor scales, Minor-key chord scales, Harmonized Scales, Chord substitutions and the Treble Clef.