composition

Key and Mode changes in a Piano/Bass piece

Carlos Franco-Galván Composition Techniques , , , , , ,

Usually Mode and key are modified to obtain the desired contrast in a composition. In this case we discuss different strategies of change using a piece for piano and electric bass.

Let´s look at the score:

pieza piano y bajo_modDescarga

The first bars directly pay tribute to Beethoven´s Emperor Piano Concerto, In this case, the piano acts as the orchestra and the electric bass plays the part of the piano in the german composer´s work. The interaction of both instruments works by establishing a major chord followed by 4 bars of free improvisation of the bass. It is worth mentioned that in Beethoven´s works, what was originally thought as improvisation, became music printed on the score as any other melodic part.

First contrast: The motif shows up in bar 12 it is clearly in the key of C but then it transforms to C mixolydian which acts as the secondary dominant to F in bar 15. Immediately afterwards the motif retrogrades in bars 16 and 17 (second contrast).

The third contrast appears in bar 18 where the motif reduces its time from 16th note to 8th note (augmentation).

Fourth contrast can be found in bar 23 where the rhythm changes to eight notes (diminution) giving more attention to the electric bass, that moves in a walking bass fashion. Also in bar 23 a Dm takes the lead without completely modulating to that key.

In bar 28 a fifth contrast occurs in the piano where a modal interchange takes place from Dm to D and then to D locrian in bar 29.

Bar 29 shows another change, this time it goes back to the original motif in C but it suddenly changes next to its parallel minor Cm (sixth contrast).

The key moves again to Dm in bar 34 and changes mode to D locrian and again to Eb in bars 35 and 36 respectively. This represents a seventh contrast till it finally moves to the key of E in bar 39.

From bars 40 to 47 the bass features taking the melody in E. The eight contrast appears and from 48 to 50 the key of Dm is visited.

From bar 51 the key changes to its parallel major D and the piano comes back predominantly again (ninth contrast). Harmony changes from Bm to D and in bar 55 to 59 the bass and the piano play around in contrary motion (tenth contrast). Bars 57 to 59 move slowly to announce the end of the piece.

The eleventh and last contrast from bars 60 to 63 present the original motif diminished in time and tempo to say goodbye.

The recording can be heard here:

Secondary Dominants in II-V7-I progression

Carlos Franco-Galván Composition Techniques , , ,

A popular way to enrich a chord progression is by adding dominant chords to the existing ones. The dominant chords are the V as if each chord were the I in its respective key.

For example if we had the typical: C-Am-Dm-G7 the enhanced variation using secondary dominants would be C-E7-Am-A7-Dm-D7-G7.

There is more to it. Each secondary dominant can be preceded by the II chord of the assumed tonality where the V was placed.

If we take the given example C-Am-Dm-G7. The resulting progression adding the II-V of the original chords would be:

C-Bm-E7-Am-C#m-A7-Dm-Am-D7-G7.

Minor sevenths can be used in the II chords whenever chosen.

C-Bm7-E7-Am-C#m-A7-Dm-Am7-D7-G7.

The way the dominant V resolves to the tonic I is because V7 contains the tritone, the three note interval between the fourth and the seventh (e. g. F and B). As it well known the tritone is most unstable interval, the fourth tends to move towards the third while the seventh reaches for the tonic.

And besides the V7, the tritone can be found in other chords, look at the following image:

Secondary_DominantsDescarga

The notes in blue form the same tritone found in V7, in this case we show C as the tonic, therefore, the tritone is formed by F and B. Considering this, we can obtain different kinds of secondary dominants.

The first case shows the traditional example that conforms the natural II-V-I progression. The second case known as Dominants by Extension involves the dominant of the dominant. Sometimes noted as V/V. In the case of G7, its V7 is D7.

The third case shows a V7 that substitutes the natural V7 in the tonality. B in G7 can enharmonically be Cb in the Db7 chord which is the same sound as B, the tritone in Db/ is exactly the same as in G7, it can then substitute this chord and solve to C giving a different color due to the rest of the notes in Db7. It is called Substitute Dominant.

We have then in the image the case of Contiguous Dominants, this happens when a dominant is a second mayor distance from the natural dominant. It happens all the time in a Blues form when changing V7-IV7. And it can be also used instead of II.

The last two cases come form minor modes, the relative minor and the parallel minor. Let us explain the Relative Minor dominants. This case is a II-V-Im, but instead of solving to the relative minor (Am in the case of C) they solve to I. The example shows Bm7-E7 resolving to C, when it normally goeas to Am.

Finally we have the Interchange Modal Dominant, which once again come from II-V-Im but refering to the minor parallel. For the situation discussed here it would be Cm, the II and V7 of Cm are respectively Dm7(b5) and G7 that solve to Cm but they can also move towards C changing the mood from minor to mayor.

Once again II-V7-I is proved a very useful tool for arranging and composing, here we have another example of a composition in the style of a Jazz Standard:

chord diverseDescarga

It was thought as a short melodic motif to improvise melodically and harmonically acording to the cases mentioned above. The audio can be heard here:

Polychords, applied to a composition

Carlos Franco-Galván Composition Techniques , , ,

Now we will present the use of polychords in a piano composition of mine.

We provide the audio and show the score here:

PoliacordesDescarga

The polychords appear from the very beginning. The first measures display them; according to Persichetti (1985), it is advisable that the lower chord have the voices as open as possible to avoid sounding too “muddy.” In this piece, instead of using a block chord, we limit the left hand to bass notes on the root and fifth of a C major chord. It is worth mentioning that these are the only bass notes used throughout the entire piece.

The right hand of the piano presents the upper chord; the progression goes A, B, D, F, and C. In measure 5, the theme changes but continues the idea of polychords: C, D, B♭, and C appear in the right hand.

In measure 9, there is a third theme that creates a kind of 3-against-2 polyrhythm; the bass continues alternating between C and E, while the right hand insists on a B♭. From there, the piece moves forward until measure 13, where the initial themes return.

Measure 27 introduces a melodic idea moving toward the Lydian mode of C. It can be seen that the chord in the bass remains insistent: a C major chord. Finally, the piece closes by revisiting the first two themes and resolving on C, giving a sense of tonality.