Extending the range of chords you can use
Last week we covered information on how to form the primary triads in a major key. This week we will look at an alternative way of forming chords that will rely on using intervals. Intervals are a great way of measuring the distance in pitch between two notes.
We will be using major thirds and minor thirds to work out the different chords. To get to a note that is a major third higher than your starting note, you need to count up 4 semitones. For example, starting with the note G you would count up 4 semitones like this:
The note B is a major third higher than the note G.
To count up a minor third you need to count up 3 semitones like this:
The note D is a minor third higher than the note B.
Forming a major chord is a simple process of combining the use of these two different intervals. A major chord is made up of a major third, and a minor third. Like this:
To form a minor chord, all you need to do is have a minor third and a major third like this:
Scales and Triads
If we go back to scales once more, we can see below that the triads build on every note of the scale. For the sake of simplicity, we will use the key of C. This can of course be applied to any key!
In traditional harmony, the chords that are most often used are chords I (tonic), IV (sub-dominant), V (dominant), ii (super tonic) and chord vi (sub-mediant). For ease, it is conventional to use upper case letters when describing major chords, and lower case letters when describing minor chords. Popular music will often use chord iii (mediant) in addition to the chords listed above.
The diminished chord is a chord that is made up of a minor third and a minor third. It is easiest to think of this chord as a chord that is squashed as both intervals are minor thirds. For example, C Dim would contain the notes:
C Eb Gb
The augmented chord is best thought of as a stretched chord as it is made up of a major third and a major third. Therefore the chord C Aug would contain the notes:
C E and G#
It is possible to extend this further by adding 6ths, 7ths or looking into suspended 2nd and suspended 4th chords. This uses the same principles to take things forward a little more and create a wider variety of harmonic possibilities. This can be very useful for composition or arranging but also can help in terms of understanding what part of the chord you are playing.
This understanding can help with your awareness of tonality and improve your intonation. Very often there will be a note that is doubled from the triad giving a four note chord. This provides the possibility of writing four-part harmony, developing awareness of root position, 1st inversion and 2nd inversion chords. If you are interested in developing this knowledge click here to explore a new course that will help you to achieve this.