So far in the course we have considered the contruction and applications of Major Seventh, Minor Seventh, and Dominant Seventh chords. Here we will review these chord types and also consider a wider range of four note (tetrachord) Seventh Chords.
Take note: some of these fingerings serve only to illustrate the idea of making alterations to more common, known forms to achieve these chords, to the end of helping with memory and understanding of the chords and their aplications. These are not the most practical fingerings for some these chord types. See the bar chord forms in the upcoming page for more practical fingerings of the M7#5 and the minor sounding seventh chords.
Major and Major Seventh Chords for Guitar
From our discussion of triads recall that we build chords, in the most basic understanding of the concept, from odd number intervals of a key. So for a major triad chord we select the first, third, and fifth intervals. We are going to continue with this same concept and extend it to include the seventh interval note. For simplicity we will start with a C Major Seventh, since the C major scale has no sharps or flats. So according to the interval relationships we learned previously, the notes of the C major chord are C, E, and G. Now, in accordance with the name of this new chord we are building, Major Seventh, we are going to add the seventh interval note for a four-note chord. The new extra note will be a B note. So here is what our new chord looks like.
The Major Seventh Chord has an upbeat but mellow mood and this works well as the I, IV, and V chords in a James Taylor-ish ballad kind of song. It also works well as the VI chord in a minor progression. You will see this chord type labeled in various ways: CM7, Cmaj7, C?7.
Dominant Seventh and Dominant Seventh Augmented Fifth (7#5) Chords for Guitar
Now let's review the Dominant Seventh Chord. You will see this chord often as the I, IV, and V chords in blues style songs, and it shows up in other types of common chord progressions as well, as the V chord. It has a tense sound due to the conflict between the Major Third and Minor Seventh intervals. We construct this chord type by adding the seventh interval note, as the name implies, but also flatting the seventh note by one half step. In the case of our C Major Seventh Chord above, we change the B note to a Bb (B flat). This chord is the most commonly used of the family of Seventh Chords, so we refer to this one as simply the 7th Chord. So when there is a reference to a 7th chord with no other information offered, assume it is referring to a Dominant Seventh Chord.
The Seventh Augmented Fifth Chord is similar to a Dominant Seventh Chord, but with a sharp fifth interval in addition to the major third and flat 7. It is also commonly referred to as a Seven Sharp 5 Chord. This chord is similar in mood to a Dominant Seventh chord, but with the additional tension of the sharp fifth interval. So it works well as a substitute in place of the typical Dominant Seventh chord in the V position. You will see this chord labeled as 7Aug5 or 7+5 or 7#5.
Minor Seventh and Minor-Major Seventh Chords for Guitar
With the Minor Seventh Chord we are leaving the family of major sounding Seventh chords that use the Major Third interval. For the Minor Seventh we will use flatted third and flatted seventh intervals. It is similar in mood to a standard Minor (Minor Triad) chord, but even more melancholy, yet somehow a little more smooth than the Minor Triad. Use it as a substitute for the Minor Triad. You will see this chord labeled as m7 or -7.
The Minor-Major Seventh chord uses a flatted third and major seventh intervals. This is an odd sounding chord and does not have much use as a stand- alone chord, but works well as a brief transitional chord following a Major Seventh chord. You will see this chord labeled as m(M7) or m/M7
Minor Seven Flat Five (7b5) and Diminished Seventh Chords for Guitar
The Minor Seven Flat Five Chord is similar to a Minor Seventh Chord, but with a flat fifth interval in addition to a flat third and flat 7. It is also commonly referred to as a Half-Diminished 7th Chord. It is a very tense sounding chord in the same way that the Dominant 7 chord sounds tense, but the Minor Flat Five sounds even more tense than the Dominant Seventh. As such, it is useful as a substitute for the Dominant Seventh as a V chord, or as the ii chord in a minor chord progression. You will see this chord labeled as m7b5, half dim7, or Ř7
The Diminished 7th Chord is again the next degree of dissonance beyond the Minor 7b5, having increased the “minor-ness” by additionally flatting the 7th interval note by another half step. So the intervals for the Diminished 7th chord are flat third, flat five, and double-flat seventh. It is a sort of "super minor" chord, but functions in the same way as a Dominant Seventh chord due to the inherent tension in the chord. Like the Minor Seventh Flat Five, you can use it as a substitute for the Dominant Seventh in the V position or as a ii chord in a minor progression. You will see this chord labeled as Dim7 or °7.