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EMT Lesson Three  How to create and play chords

Introducing the diminished chord

The seventh chord of the major scale.

So far we have developed the concept that chords can be built on each note of the scale using triads. These triads have all been major or minor triads. However, there is a notable exception that you need to be aware of:

    The seventh chord in the scale is a diminished chord.

If you look at the A major scale, you will see that the seventh is G#. Harmonising in thirds from G# gives: G#, B – which is the ninth (9th), and D –which is the eleventh (11th). You will see that we are now beyond the octave in building the chords. The octave is the eight (8th) and we simply continue upward.

Figure 5. Scale of A major (extended beyond the octave)   (Enlarge)

Figure 5. Scale of A major (extended beyond the octave).

If you look at the diagram of the keyboard you will notice that the interval between the seventh and ninth notes is a minor third. The interval between the ninth and eleventh (B and D) is another minor third interval. This means that the interval between the first and the fifth is six semitones (minor third (3) + minor third (3)) rather than the seven semitones of the perfect fifth found in the major (4 +3) and minor (3+4) triads. This gives a flattened fifth (b5th).

Figure 6. G# diminished (G#dim) chord   (Enlarge)

Figure 6 G# diminished (G#dim) chord.

A diminished chord is similar to a minor chord as it contains a flattened third. The diminished element is produced by the flattened fifth. A diminished chord is, therefore, built with a root note, minor third and diminished (flattened) fifth and is noted as:

Diminished chord: 1, b3, b5.

Next: Further studies – more chords