Parallel keys and scales are keys and scales that share the same root. Understanding this concept is very useful to songwriters and for improvisation.
Many prominent songwriters employ parallel keys and/or parallel scales in their songs. The Beatles frequently used this device, in “While My Guitar Gently Weeps”, the verse is in the key of A minor and the bridge is in the key of A major. In “Penny Lane”, the verse is in B major and the bridge is in B major. Finally in “Norwegian Wood”, the verse is in D major and the bridge is in D minor.
You can also use parallel scales to great effect. An example I frequently teach students I,s parallel scales you can you to solo over a traditional dominant blues 12 bar progression. If, for example you're playing blues in the key of G, parallel scale options would be the G minor blues scale, G major blues scale, G mixolydian scale or G dorian scale. Those different scales offer a massive amount of varitey, especially if compounded (mixed together) creatively.
Lastly, another interesting trick you can use is to end a song on the parallel I chord of the key. So, if the song is in the key of A major you can end on some form of an A minor chord and if the song is in A minor, you can end on some form of A major.
It's useful to think of relative major and minors as the same notes or chords but with different starting and end points. For example, C major and A minor are reciprocal relatives to each other, both key have the same notes and chords, in this case, all natural notes. A C major scale is C through C natural and an A minor scale is A through A natural, the same notes but with different starting and end points.
It's also useful to learn to identify the relative minor key and scale contained within the major key and scale and the reverse. (the major key and scale contained within the minor key and scale)
If you play a two octave C major scale for example, the A minor scale is the same notes beginning on the sixth degree of the scale and going past the octave to the thirteenth and if you play an A minor scale in two octaves, the C major scale is the same notes but beginning on the third degree of the A minor scale and going past the octave to the tenth scale degree.
The concept of relative major and minor keys and scales is very useful for understanding composition and improvisation. Relatives share the same notes. Every major key has a relative minor key and every minor key has a relative major key. Every major scale has a relative minor scale and every minor scale has a relative major scale.
Here is a simple formula you can use to calculate the relatives: If you're in a major key or scale to find the relative minor simply move a minor 3rd lower (three half steps) which on the guitar or bass is 3 frets lower (to the left) for example, C is at the eight fret of the E string, if you're in the key of C major to find it's relative minor, move three frets lower which is A. A minor is the relative minor of C major, this applies to both the key and the scale. The keys and scales of C major and A minor contain the same notes, in this case, all natural notes.
Conversely, if you're in a minor key or scale, to calculate it's relative major, move up a minor 3rd. If you're in A minor, move up three frets and that gives you a C, C major in the relative major to A minor.
To reiterate in simple terms: major to relative minor = up a minor 3rd and minor to relative major = down a minor 3rd.
Tune in next week for Part 2 of this series...