Al's Music Tidbits - Volume 9
So, perhaps a bit of review is in order. In a major key (most Bluegrass songs/tunes are in major keys), the chords formed by stacking two intervals of a third on top of each scale degree are:
I major triad (notes 1, 3 and 5)
II minor triad (notes 2, 4 and 6)
III minor triad (notes 3, 5 and 7)
IV major triad (notes 4, 6 and 1)
V major triad (notes 5, 7 and 2)
VI minor triad (notes 6, 1 and 3)
VII diminished triad (notes 7, 2 and 4)
The triad on the “leading tone” (7th degree) is virtually never used as such, but it sounds like a V chord, the reason for which will be explained shortly. In Bluegrass, a large majority of songs and tunes use only the I (tonic), IV (subdominant) and V (dominant) chords, and most of the rest use those plus a VI ( submediant, E minor in the key of G, for example, as in “Down the Road”).
The dominant-to-tonic progression (V to I) is generally considered the most “satisfying”, although this is very subjective. If you play a G chord to establish the key to your ear, then play the open D string followed by the G note on the low E string (3rd fret), you will probably get a sense of “repose”. Note that in this progression the root is moving up a fourth (or down a fifth). Other “up 4” progressions have a similar effect, like I to IV or II to V (Am to D in the key of G). Many, many phrases in Bluegrass songs end with an “up 4” change. Another factor that makes it a strong change is that the leading tone (7th degree) has a natural tendency to resolve upward to the tonic, which it does in most V to I progressions.
Movement of the root up a fifth (down a fourth) gives the opposite effect; one gets a sense of incompleteness, an expectation of a return. Quite a few Bluegrass songs have a verse or chorus that consists of just a I V I progression, probably repeated (verses of McReynolds Brothers’ “I Wish You Knew” and The Dillards’ “Never See My Home Again”). I think of this pattern as driving up a hill, then coasting down the other side.
If it weren’t for the feeling of key, or tonal center, the I to IV change would be indistinguishable from the V to I; indeed, the V to I change in G is the same chord progression as I to IV in D. So, how do you tell the difference? The key is the set of chords and notes. In the key of D, the leading tone is C#, a note foreign to the key of G, which has C natural as the fourth degree. So, the V chord in D is A major, also foreign to the key of G. The IV, V and I chords clearly establish the key, whether C, D and G or G, A and D.
To me, the I IV change sounds like going down a hill, then climbing back up via IV to I. The IV chord, however, often progresses to V rather than going back to I, and there are many phrases that end with IV, V, I.
Suppose you are in the key of G, playing a IV (C) chord, consisting of the notes C, E and G, with another C in the bass. The next chord is D major, but as the bass C (4) progresses to D (5), the E (6) note progresses to F# (7) and the G (1) goes to A (2), the C note is held over. This is called a “suspension”, and is a very common melodic device in music. Let’s examine the resulting chord for its intervals. Here are the notes:
Can we name the intervals?
D to F# - major third
D to A – perfect fifth
D to C – minor 7th
F# to A – minor third
F# to C – diminished fifth
A to C – minor third
We recognize a D major chord in there, right, major third and perfect fifth over the root and a minor third between the 3rd and 5th of the chord? (Remember that a triad has a root, 3rd and 5th.) But now we have another note, which is another interval of a third stacked on top of the triad’s two. This is called a “seventh chord”, in this case a “dominant 7th”. You play this on the guitar by fretting the B string at the first fret, not the third, when you make a D chord. This chord has an even stronger tendency to go to the tonic, because in addition to the root change from D to G (V to I) and the leading tone F# tending upward to G, you have the C note tending downward to B, the 3rd of the tonic chord. In addition, we now have two “dissonant” intervals, the diminished fifth between F# and C and the minor seventh between D and C. The diminished fifth (tritone, three whole tones), which has been called “diabolus in musica”, has a strong tendency to resolve to a major third.
This chord, V7, can establish the key all by itself, because it contains both the leading tone and the subdominant, F# and C in the key of G. G is the only major key that contains both those notes. In C major, F is natural, and in D major, the next key around the Circle of Fifths, C is sharped. In Bluegrass, the guitar player often does not play the V7 chord for the V, but you will hear that subdominant note somewhere in the melody line, a harmony part or in one of the lead instruments, more often than not.
By the way, the reason that the triad built on the 7th degree of the scale sounds like a dominant is that has all the notes of the dominant 7th chord except the dominant. It has a strong tendency to resolve to the tonic, because of the leading tone and the subdominant.
Next time, “secondary dominants”.
Any questions or suggestions for subject matter may be sent to: email@example.com.
Last week, I took a detour into humor, only half of which was printed, unfortunately. The part that disappeared into thin air contained a bunch of almost-believable bull about Bill Monroe bending his double strings to get a slightly different pitch out of each, then ended with “April Fool!”. (Editor's Note: The article was originally printed in April.)
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