7th chords

By adding the note “B” to a C Major triad, we can create a C major 7th chord

B is the 7th degree of a C major scale. When these two notes are played together, we get an interval of a 7th.

Much like there being two types of 3rd, there are major and minor 7th intervals. Move C-B up one scale degree to D-C.

There are 11 semitones between C and B and only 10 between D and C. It is much easier to see the difference between these two intervals when the bottom note is inverted up the octave. We can see that a major 7th turns into a half step, and a minor seventh turns into a whole step. This trick can help you better see a M7 or a m7.

Let’s now play the full C major seventh chord, and continue to walk it through the C major scale, as we did with triads in an earlier lesson. While doing so, notice how the combinations of major/minor 7ths and major/minor 3rds offer a greater variety of harmonic possibility within the C major, than we saw with the triads.

Here we encounter 4 types of 7th chords: a major triad with a major 7th creates Major 7th, a major triad with a minor 7th creates Dominant 7th, a minor triad with a minor 7th creates Minor 7th, and a diminished triad with a minor 7th creates a Half Diminished 7th. Though there are other possible combinations of major/minor 3rds, 7ths, and perfect/diminished 5ths, this combination of intervals only yield 4 chord types within the restriction of a major scale. Let’s try this exercise again, but with the chord types spelled out. We will use chord symbol abbreviations to simplify the notation.

Let’s see this again with Roman numerals.

Let’s now try this in the key of G major.

And F major.

Like we saw with triads, notice how the progression of chord-qualities remains unchanged from one key to the next.

Let’s now explore the idea of closed vs. open positions. A chord in closed position will fit within one octave. A chord in open position will extend beyond one octave. An open position chord voicing can be a way of creating a richer sound, and will better distribute the notes of a chord across both hands. In the next exercise, we will keep all the same notes of the C Major 7th chord, and simply bring the “E” up by one octave.

In the exercise bellow, the author recommends playing C and G in the left hand, with B and E in the right hand.

Let’s now try this in the key of G. Here the chord symbols are spelled out.

And F major

In the next lesson, we will cycle 7th chords through a progression of 5ths, much like we did with triads.