Special Chords: Rare but Useful

In previous blogs on chord theory, we covered all the most common chords so, to make the series complete, this edition will dive into a few more special, out-there chords, including minor-majors (mΔ), augmented sevenths (+7) and diminished triads with major sevenths (oΔ). These chords are often used as transitions, so they’re definitely worth knowing about, even if they are extremely rare.

Minor-Major Chords (MMAJ7 or MΔ)
Augmented Seventh Chords (+7)
Augmented Chords with a 9th, 11th or 13th
Diminished with a Major Seventh (O(MAJ7) or OΔ)
Transition Chords
Chord Notations
See also…

Minor-Major Chords (MMAJ7 or MΔ)

We start things off with the least rare chord that we’ll cover in this blog: the minor-major chord, as it’s often called. This is a minor chord with a major 7th thrown in. Here, a C-chord becomes C, Eb, G, B. The Eb is the minor third, making up the minor part of the chord, and the B is a major seventh, making up the major 7th bit. This chord can be written in a couple of ways: Cmmaj7 or CmΔ, where the Δ stands for the major 7th. Just like the normal major 7th chords, the minor-major7 chord doesn’t have much ‘resolution’ to it. It’s more about the colour of the chord, which in this case, has a really stark colour. Dominant seventh chords like Cm7 and C7, or chords with a diminished seventh, have a much greater feeling of resolution. The minor-major7 chord is often used in certain chord progressions where the progression is driven by the highest note in the melody. This might follow a chromatic line, like C, B, Bb, A, while the chord progression runs Cm, Cmmaj7, Cm7, Cm6. Or: Cm, Cmmaj7, Cm7, F7 (where A is the third in F7). In this instance, Cmmaj7 is a sort of transition chord between the Cm and Cm7.

Augmented Seventh Chords (+7)

The other chords included in this blog are all expanded chords that we’ve already covered: augmented and diminished chords. We’ll start with the augmented chord, so an augmented C-chord can be notated C+, C#5 or Caug. An augmented chord differs from a normal major chord because of the addition of an augmented fifth. For example: C-major is C, E, G, while Caug is C, E, G#. The augmented chord is a chord that really pushes for a resolution, so it really feels like it wants to go somewhere. For example, it might want to go from the first step to the fourth step, so you can step from a C via Caug to an F (F, A, C).

You can even make the drive towards a resolution stronger by adding a minor seventh to an augmented chord and turning it into an augmented seventh chord. In the case of the Caug chord, a Bb is added, making it C, E, G#, Bb. This can be notated as C+7. An augmented seventh chord is often used as a transition chord; which is sometimes called a pivot chord. If there’s a key change in a song, this is sometimes made possible via a pivot chord. Here, the pivot chord sits between two keys and ‘borrows’ notes from both keys so it can function as a sort of bridge between both, initiating the shift and making the experience a bit more pleasing.

In theory, you could add a major seventh to an augmented chord instead of a minor seventh. So in the case of the Caug chord, the Bb is replaced with a B. However, this is really uncommon, so it’s highly unlikely that you’ll ever hear it. While no note combination is ever forbidden in music, some specific combinations are simply too difficult to slot in.

Augmented Chords with a 9th, 11th or 13th

In the last blog in this series, we introduced you to the 9th, 11th and 13th. When you take things from a C, the 9th is D, the 11th is F and the 13th is A (see the illustration below). But, can you add these to an augmented chord? You can definitely add the 9^th, which becomes a Caug9, and because (in principle) you also play a minor seventh in a 9th chord, this becomes C, E, G#, Bb, D. You could also take the 9th up or down by a semitone to give the chord even more of a push towards resolution. When you do this, it’s usually on the fifth step, so in that case we’ll use the seventh (7) in the chord notation. These chords are written and played in the following way: Caug7(b9), which is made up of C, E, G#, Bb, Db. Caug9(#9) which is made up of C, E, G#, Bb, Eb. Caug(#9) can also be notated as Caug7(b10). If you want to add an 11th to an augmented chord, then it’s best to choose the sharp 11th otherwise the 11th will clash with the minor third.

In an 11th chord, you always play the minor seventh (7), os the Caug7(#11) is made up of C, E, G#, Bb, F#. But can you also add a 13th to an augmented chord? This isn’t common, because the 13th clashes too harshly with the #5th. In a C-chord, the 13th is an A and the #5th is a G#.

Intervals counted from C (2 = major second, 3 = major third, 4 = whole fourth, 5 = whole fifth, 6 = major sixth, 7 = major seventh, 8 = octave, 9 = none, 11 = eleventh, 13 = thirteenth)

Diminished with a Major Seventh (O(MAJ7) or OΔ)

In one of our earlier blogs, we looked at diminished chords as well as augmented chords. One of the diminished chords is the diminished triad, which is a stack of two minor thirds. The thirds of the chord are minor thirds (just like in a normal minor chord) and the fifth is a diminished fifth, so a diminished triad C chord becomes C, Eb, G#.

The diminished triad can be notated in three possible ways: Cmb5, Cdim or Co. In our previous blog, we also talked about diminished seventh chords. This is a diminished triad with a minor third stacked on top. Here, Cdim7 becomes C, Eb, Gb, A. By raising the A by a semitone to Bb, we get a half-diminished chord (Cm7b5) which is made up of C, Eb, Gb, Bb – a chord we’ve also talked about before. Now, we’ll add another variation by taking the highest note of the chord (the Bb) and raising it by another semitone to B. Because of that B, the chord now becomes a major-7th chord, so the Cdim(maj7) is made up of C, Eb, Gb, B, which can also be notated as CdimΔ.

Here, we should also mention the B/C chord (a B-chord over C), or a B-major triad with a C as the bass. This is a really colourful chord that’s actually pretty hard to place in the harmonic function. The diminished triad could be further expanded with a 9th, 11th, or 13^th, but since that’s really, really rare, we won’t cover those chords here.

Transition Chords

As we’ve already mentioned, the chords discussed above are often used as transition chords, because they have this driving need to resolve to the next chord. When figuring out how to play a song, these chords can be a bit of a nuisance because those note combinations don’t exactly lie within reach. Normally, you’ll listen out for the bass notes, since they will almost always give you the foundation note of each chord. With transition chords, this is a little bit tricky, because the bass note supporting a transition chord is sometimes different from the foundation note of the chord. Often, there’ll be a chromatic walking bass line. So, under the chord progression Cm, Cmmaj7, Cm7, F7, the bass could play something like: C, B, Bb, A. When figuring out how to play a song like this, the trick is to recognise that there is a transition chord. So, once you’ve figured out the two chords that it’s bridging, you can start looking for the transition chord. Remember, the transition chord usually borrows notes from both of the chords it’s bridging.

Chord Notations

In musical notation, unfortunately, there’s no absolute rule when it comes to notating chords. A lot of chords can be notated in a few different ways and these are not always used consistently. But, most of the time, you’ll be able to understand the notation, even if you’re seeing it for the first time. In this series of blogs, we’ve at least tried to keep things as consistent as possible. In the table below, you’ll find all the chords we’ve covered and the notes they’re made out of across the different keys.

Note: At some point, the notation has been simplified to make it easier to read. For example, an Fb has been notated as an E, and an F## is simply notated as a G. Click on the image to enlarge it.