by Ivan Barasnevicius

Tetrads - formation, inversions and nomenclatures

Firstly, I would like to say again that it is a great pleasure to write this column to Guitar Clinic Magazine and I hope that the previous column about intervals has been of great utility to explain doubts about the related subject. In this second column, we will talk about a basic subject for harmony: the formation of tetrads, its inversions and nomenclatures.

Chords tetrads are chords formed by four notes ( R, 3rd ,5th,7th ). While only four types of triads exist, there are nine possible tetrads. With triads, two inversions are possible, whit tetrads, there are three inversions (obviously, there is also the basic position, in both cases). The two only exceptions are the augmented triad and the diminished tetrad, which are symmetrical structures, where all the distances between the intervals are the same. In this way, as the augmented triad as the diminished tetrad cannot be inverted, because when it happens we get another chord so the inversion in this case is something redundant.

As well as it happens with the triads, when the chord has the third on bass, we call it first inversion. When the fifth of the chord is on bass, it is configured second inversion, whereas the seventh is the bass of the chord, it is called third inversion. When the seventh is the lower note, it becomes redundant to indicate it in the nomenclature of the chord, because it is evident that the chord has four sounds.

Another important point about nomenclatures: depending on the searched source, the way to represent the chord can be different. For example: in the Real Book, the chord C7M is represented as Cmaj7, in other books we can find C7+.However, this last one certainly is not the best indication. Therefore, the signal + is used for augmented intervals and chords and although this form is sufficiently spread, it is always more interesting if we can organize the subject as objective and clearest as possible, preventing problems with the used terms. This way of wirting is also used for other instruments, not being something only limited to guitar universe. It is also important to mention that the chords transcribed here are all in closed position, which means, there’s no possibility of inserting chord notes between that ones already written. There are specific ways of playing these chords in the neck of the guitar, so those chords can have a balanced sound and can be played accordingly to the possibilities of the instrument. I also would like to remember that the rules for construction and nomenclature of the chords are accurately the same ones used for arpeggios, as arpeggios are nothing more than the chords notes being played in a melodic way.

In example 1, all the possible tetrads starting on note C are showed. After, in example 2, we will have all the possible inversions for the C7M and C7. I suggest as an exercise, build all the other tetrads in all the tones, as well as all their inversions. In example 3, they are some chords so that you can discover their names and inversions. There is a precious tip: see in which inversion the chord is. Try to find the sequence of thirds between the notes and remembers that the root cannot be necessarily the lower note. Doubts and suggestions, please write for ivan@venegasmusic.com.

Hugs

Ivan Barasnevicius