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Understanding chord theory is hard (untrue) – part 2

Jerry

Today we’re concerned with chord-scale relationships … what chords can be built from the scale members.  Remember, theory is independent of instrument.  It’s mainly about explaining note choices available and used in music.  Welcome to exploringseventh and ninth chords today.

Here’s a short demo so you can hear the sounds of these chords in a short piece I wrote for this blog.  I’m afraid my fretting hand isn’t 100% … I still haven’t fully recovered from ulnar nerve injury when I had a heart valve replaced Xmas 2019.

Watch the video

Here are the chord voicings being shown via Rhythm-X. These are in same order as in the above video, but not played to precise rhythm.

chord voicings in emuso

We’ll look at

 

Pre-requisites

You need to know about semitones, and about what intervals are present in the major, minor, diminished and augmented triads, and the “choose-skip” method for building chords.  This blog covers this in detail.  It’s critical as the most of the more complicated chords are built from these, adding additional intervals.

 

New intervals

The major ninth is interesting, as it strays beyond the range of the 12 semitone block of notes contained in an octave, and is found 2 semitones above the start note of the next octave.  However, when improvising, we can use whichever we  choose to provide a “ninth” even though theoretically it could be in the wrong octave.  It can also sound pretty cool playing the ninth in the bass.

 

Seventh chords in major scale

In the previous blog, we used choose-skip to choose 3 scale members starting at different scale members for the chord root.  This gave us triads.

If we now choose 4 scale members instead of 3, the chords we find will have these same triads , plus one additional member.  This member will be located at either 10 or 11 semitones clockwise from the chord root.  However, visually, we can get to the same location by looking 1 or 2 semitones counterclockwise from the root (in which case 1 is equivalent to 11, and 2 is equivalent to 10 semitones). This makes it really easy to recognise whether a chord has a major 7th or minor 7th interval.

Here’s what we find.  Remember to try this yourself on a piece of paper with the clock drawn on it.

 

Ninth chords in major scale

If we now choose 5 scale members instead of 4, the chords we find will have above seventh chords , plus one additional member.  This member will be located at either 13 or 14 semitones clockwise from the chord root.  However, on the clock this is exactly the same visually as being located at 1 or 2 semitones clockwise from the root.  Pretty convenient!!

Here’s what we find.  Remember to try this yourself on a piece of paper with the clock drawn on it.