My last post explained the concept of “key shapes”, an easier way
to find out the chords in any key by following the shape and
sequence the chords formed on the fretboard. That post referred
to major keys, this post is about blues keys. Blues harmony is the
foundation of most popular modern music; rock, jazz, modern
country, R&B, etc. so even if you don’t like blues music you still
need to understand the harmony! As with the previous post on
major key shapes, the theory behind blues harmony is advanced.
My book, “Take Control: for guitar”, explains this in more detail,
but the short explanation is that a blues key equals a major plus
a minor key added together. These 2 keys are both built off the
same root, i.e.. E blues=E major+E minor. This major/minor
combo gives blues harmony both a distinct sound and a distinct
shape. Blues keys jump 3 frets from the root, then 2 frets, while
major keys jump in 2 fret + 2 fret intervals as I showed in the
last post. In addition the scale is different than the pentatonic
scale, since a blues scale contains notes from both major and
minor scales, it’s got a lot of notes! (Here is pos. 1/type 1 root)
Use the same root as the pentatonic minor, the first finger,
5th fret is A blues. Below I am showing the same key shapes
diagram as the last post. This time we want to look at Blues
key shape on the lower right hand side. We will use this
shape to find the chords in the key of A blues; A,C,D,E,F,G.
If we start this pattern on the 5th fret, our type 1 root is
A (looking at the 6th string table on the left side of the
diagram). The root chord for this pattern will always
be a type 1 chord. The next chord goes up 3 frets to C
major (bIII), Then we switch to type 2 chords and get
the D (IV), E (V), F (bVI), and G (bVII). Notice that
the V chord is the only chord that’s not 3 frets higher.
This illustrates an important point; the I, IV, and V
chords are the same for both major and blues keys.*
check the major key shape on top right if you need to.
This means if your song only contains a I,IV,V chord
progression you could be in either major or blues!
This means both a major and a blues scale will work,
which one you use will depend on the style of the
song; both Johnny B Goode and Oh My Darling
Clementine use A, D, and E chords when played in
the key of A, but I would use a blues scale for J. B.
Goode and a major scale for Clementine. You don’t
have to play only the types of chords in the shape
above, either. You only use the shape to find out the
chords to play, once you know what chords to play
you can play any version of those chords you know.
(* If you look closely at the blues key diagram above
you will notice that the I,IV, and V chords are both
major and minor. That’s not a mistake! Blues
harmony is both major and minor and it’s quite
possible to have both a D major chord and a D minor
chord in the same song, in fact it’s one of the things
that tells me I’m in a blues key.)
The next post will sum up what we’ve learned over
the past 4 ” quarters”.