Bass technique: Franc O’Shea

Unlike with triads, there are not only two inversions available for 7th chords – there are three. There is root position (1, 3, 5, 7), first inversion (3, 5, 7, 1), second inversion (5, 7, 1, 3) and a third inversion (7, 1, 3, 5), due to the fact that 7th chords contain four notes. Simple voicings are used for convenience here, but there are other voicings that work in practice.

With 7th chords in first inversion using A string roots, how could we convey the sound of the chord using just three notes? As you can see from the voicings shown in brackets above, first inversion tertian (constructed in thirds) chords always have the 3rd as their lowest note, so it follows that the 3rd of the chord will be placed on the A string. Since the 5th of a chord tends to just double up the root (unless the 5th is altered), the root, 3rd and 7th are the integral components of 7th chords – and the 5th can be omitted.

The most convenient way to add the root and 7th to the 3rd starting on the A string, is to place the 7th on the D string and the root (an octave higher than in root position) on the G string, as demonstrated in the first bar of example one. This shape can be awkward for the left hand to fret. I use my second finger for the 3rd on the A string, my third finger for the 7th on the D string and either my first finger or left hand thumb for the root on the G string. I do this by pulling my thumb from under the neck and onto the fingerboard.

Example 1

In the second bar of example one you will notice that the voicing for the 7th chord is similar to the major 7 chord shown in the first bar, with the 7th of the chord differing by only a semitone. Looking at the third bar, we only have to lower the third of the dominant 7 chord (C#) by a semitone (to C) for it to become a minor 7 chord. Likewise, if we raise the b7th (G) of the A minor 7 chord a semitone to G#, it becomes a minor major 7 chord (1, b3, 5, 7). You may find that, when playing the AminMaj7/C, it sounds very dissonant, but once again a chord like this needs a context. It may be used as a tension chord that resolves, or to create an enigmatic sound. You may also find that it sounds more satisfactory when arpeggiated (each note sounded separately, rather than simultaneously).

So far we have covered four of the six main types of the thirteen 7th chords. The six main groups are major 7, dominant 7, minor 7, minor major 7, half-diminished 7 and diminished 7. The minor 7 shape will suffice for the half-diminished 7 chord as shown in bar five, as they are exactly the same apart from the 5th, which is a perfect 5th in the case of the minor 7th chord and a diminished 5th in the case of the half-diminished 7 chord.

You may wonder why we don’t also use the 3rd, 5th and 7th for 7th chords and their inversions. The reason, as I have explained previously, is that by leaving the root out and just playing the 3rd, 5th and 7th, you are actually playing a triad that is complete in itself. For example, Cmaj7 contains the notes C, E, G and B. If we leave out the C, we are left with E, G and B, which is an Emin triad. You could use this as a substitution for the Cmaj7, but in reality it is an Emin and not a Cmaj7.

In the sixth bar of the first example, we see the fully- diminished 7th chord with its b3, bb7 and root an octave higher. Bars seven to 12 demonstrate the same shapes as the first six bars, but are shown at the position for C. You should get used to playing this shape in every key, and as you look at the shape, you need to be able to recognise each note in the chord as an interval of the overall root note.

Every time I play a chord I am aware of its root note in both the upper and lower octaves of the position I am in. With inverted chords, there is no room for guessing! We have ascertained that we can’t effectively retain the sound of a 7th chord using just the 3rd, 5th and 7th, as it becomes a triad a diatonic 3rd up from the root of the chord. However, this doesn’t prevent us using the 5th, 7th and root for playing second inversion 7th chords with only three strings.

Example 2

Example two demonstrates this solution. In the first bar, we have a Cmaj7 chord using the 5th on the A string, the 7th on the D string and the root on the G string. This chord presents difficulties for the left hand, but it can be played with either your second or third finger for the 5th on the A string, your first or second finger for the 7th on the D string, and your left hand thumb for the root on the G string. Since these voicings include no 3rds, the major 7 shape works for the minor major 7 shape, as does the dominant 7 shape for the minor 7 shape. The Adim7/Eb chord (as b5, bb7, root) is the same as an Ebdim triad due to the symmetrical nature of diminished 7th chords.

Since we are using 5ths in these second inversion voicings, we can also effectively represent the 7th chords with altered 5ths (#5 and b5), as demonstrated in bars seven to 13 in example 2. The voicings for the minor major 7 chords with altered 5ths are the same as the major 7 voicings with the altered 5ths.

This is because there are no thirds used in these voicings. The same goes for the 7#5 and the minor 7#5. The minor 7b5 is
not included separately as it is the same as the half diminished 7th chord. When playing third inversion 7th chords using three strings, we need to put the 7th of the chord on the A string as the lowest note, leaving the D and G strings free for the root and the 3rd.

Example 3

Example three demonstrates the solution, and you will notice that the Cmaj7 shown in the first bar has the 7th on the A string, the 3rd on the D string and finally the root note, placed an octave higher, on the G string. All the third inversion 7th chords in example three share this shape, except for the Cdim7/A in the sixth bar. You could play this chord using the same shape, but it is awkward. It is more convenient to place the bb7 and the b3 on the E and A strings as demonstrated in the tab for bar six.

Once again, because of the symmetrical nature of diminished chords, this now appears as a diminished triad in root position with an open voicing. You will also note that, in brackets, the root for this chord is Bbb. This is the correct name for this note – but it would more likely be written as A, as double flats can be confusing to sight read.

Next month I will be looking at creating 7th chord inversions using E string roots. Until then…

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