In the last post I introduced the concept of harmonic
categories and used the key of C for an example. I also
used both chord and degree names to make it easier to
change keys. In order to understand this post you have to
have read the first post! Also if the idea of keys or
degree names is fuzzy to you, stop and read my book “Take
Control:for guitar” available on Amazon. Before we go
further I will list the 3 categories and their chords again,
for reference. ( Again this is the key of C).
Tonic-C major (I), E minor (iii), A minor (vi)
Subdominant- D minor (ii), F major (IV)
Dominant- G major (V), B diminished (viiº)
The terms tonic, subdominant, and dominant refer to the
harmonic function the chords perform in their respective
categories. Over the years, the way I’ve come to explain
this concept is with my “famous” field metaphor. Pay close
attention, it’s stuff like this that rakes in the big $.
(see the diagram below the explanation)
THE FIELD METAPHOR: Picture a key as being a big field, and
the fence closest to you is the Tonic fence. This area
contains the root chord (I-C) and the two related chords,
(iii-E minor and vi-A minor). These 3 chords are like home
base in the key, either the root chord C, or the 2 chords
closest in sound, E min. and A min. You can play all 3
of these chords and hear how similar they sound, there’s
not much movement between them sound-wise. That’s why you
can substitute these chords for one another, there’s not
that much difference in sound. Now on the far side of the key
“field”, visualize the opposite fence, that’s the Dominant
fence. This area contains the V chord (G or G7) and its’
related chord the B diminished (viiº). These 2 chords are
the most distant in sound from the Tonic chords. Play a
G to C or B dim. to C and hear the jump in sound, especially
compared with A min. to C (same category). Jumping from
Tonic to Dominant to Tonic is as much sonic distance as you
can cover in a key (and is called a cadence). These two
categories can completely define a key and the simplest
songs contain one chord from each category, generally
the I and the V, the most common members of their
categories. Songs like Jambalaya (C-G), only have 2 chords
because that’s all they need! The boundaries of the key are
set. Other I-V 2 chord songs are Tulsa Time and Achy Breaky
Heart (but those are in different keys). Finally, in the
middle of the key “field”, along with the daisies and cow
patties, are the Subdominant chords. These chords occupy the
middle ground in the key, further away harmonically from the
root than the Tonic chords, but not as far away as the dominant.
( see diagram below)
———————DOMINANT FENCE—————————-
(V -G and viiº-B dim.)
——————-MIDDLE OF THE FIELD———————-
(ii-D min. and IV-F maj.)
———————–TONIC FENCE———————————-
(I-C maj., iii-E min., and vi-A min.)
PRACTICAL USES: Like I said in the previous post, you can
substitute chords inside a category; if a song goes C-F-G, try
C-D min-G, or A min-F-G. This can add a lot of creativity. This
knowledge also helps me when I’m figuring out songs; a chord
will sound close, but not exactly correct. Often it turns out
to be another chord in the category. When I’m playing with
another guitarist or keyboard player, I can play different
chords against them inside the harmonic category (I can play
an A minor or E minor against their C major.) Whether I’m
composing, jamming, or figuring out songs, my knowledge of
harmonic categories gives me an edge.
