17 – Quintets

A ‘viola quintet’ to a model by Mozart : building a 12-chord sequence and using the chord-variation function : rhythmic articulation using the metrics of Classic poetry :  making a dialogue from melodised chordal material extended by looping : devising and working with a library location to store and retrieve poetic metrics : expanding rhythmics with length-augmentation  :  using length-rest-weight and length-condense for melodic variants :  deriving a metric structure from a poem  : a different quintet – Omphalus for piano and four percussionists : working with six of everything – clusters, Slonimsky patterns, and rhythmic motifs.

In writing for a ‘viola quintet’, the string quartet plus an extra viola, the composer is following a path already taken by Mozart, Beethoven, Mendelssohn, Brahms, Dvorak and Bruckner. Contemporary quintets of this scoring are rare but three stand out, Painting by Numbers by Simon Roland-Jones, the Quintet (2009) by Bruno Mantovani, and The Death of King Renard by John Woolrich.

Mozart’s C major Quintet K515 was one of the most ambitious of the five quintets he wrote. It has a large-scale sonata allegro as its first movement, which became the model for my own single movement quintet, my first major composition using the Opusmodus CAC system:

17-1Mozart (top), Morgan (bottom).

It is easy to see the similarity in the texture between the two compositions: the first violin and cello have an antiphonal dialogue and the second violin and the two violas play a chordal accompaniment. But that is where the similarities end.

The composition process began with devising a chord sequence that could be scored, like in Mozart’s opening, for second violin and two violas:



This complex expression contains a series of sub-expressions beginning with:

17-5Twelve lists of 4 pitches are generated from a list of integers that correspond to a chromatic scale beginning with the G below middle C (the lowest open string of the violin) to the B an octave above. The reason for choosing 4 rather than 3 pitches is to get a wide range of pitches from which to pick a random sample:

17-6These lists of pitches are made into chords with a chordize function and then one of the four inner pitches removed with chord-inner-remove. Finally, a function chord-variation steps in: it inverts or mirrors the chord, though does not change the interval size in any way. Only the transposition is changed, but in a random fashion. Now the chords are ready to be ordered using the substitute-map function:

17-7The next step is to create a rhythmic articulation of the chord sequence. Rather than Mozart’s pulsing repeated 1/8th notes, a sequence of rhythmic groups were created from the standard metrics of classical poetry:



Using the same process adopted for the rhythmic grouping of poetic metrics, a dynamic scheme is created, This scheme is fundamental to articulation of the rhythmic groups, and responsive to the violin and cello dialogue that will surround the chordal rhythms:



The melodic dialogue between first violin and cello is based on the melodising the chd-play variable, the collection of chords shown above. In the code expression below for the cello part. Notice, by viewing the score extract below, how the melodised chordal part of three pitches will loop in 1/16ths inside the metrical period of each bar:

17-12tmp2Melodic looping of violin and cello material.

In Part 2 from bar 17 to 32 the structural design is similar to Part 1 only there’s a difference in the organisation of the poetic metrics. In this part they are gathered from a library. Using a library location to store material can be a very efficient way of bringing pitches or rhythms into the score-script, either by filling a template, or as in this example calling library entries randomly into a list.  Here’s the library entry and the code expression:

17-14In part 3, from bar 32 to bar 47 the chordal trio of second violin and violas still calls the poetic metrics but its rhythmic groupings within each bar are processed by the function length-augmentation. The chord sequence itself focuses on the chords that were not called from the original sequence from bar 1 to 16. So a different tonality for this section ensues:

tmp3Violin 2 and viola parts from bar 32- 47.

The violin and cello parts are conceived in a similar way to their music in parts 1 and 2 only with more complex rhythmic patterns created with functions length-rest-weight, applying measures of probability to the conversion of lengths to rest-length , and length-rest-condense, a function that brings together or ‘condenses’ rest-lengths. Here’s an example of both functions:


tmp4Violin and cello parts only from bar 32 -47.

At this point in the score-file the first section of the work ends and the three parts of the piece are brought together. It was then that the composer decided to change the arrangement of material shown above, exchanging the violin’s music for the cello’s music in bars 32-47. This is a good example of the use of the ambitus function to readjust pitch material. The final part of the first section of the Quintet now looks like this:

tmp5The final part of the first section after the changes made to violin and cello.

The second section of this String Quintet has two progressive features: the chordal trio continues in a play of poetic metrics but organised to follow the pattern of a short poem; the first violin and cello continue to play as a duo moving from their previous antiphonal duet to a continuous two-part contrapuntal texture.

Using a poem to create the metrical and affective / dynamic structure of a piece of music is a popular device amongst composers. Hans Werner Henze’s composition for cello and orchestra Englishe Lieberlieder (1984) is a celebrated example about which Daniel Pappas has written:

His aim in Liebeslieder, for cello and orchestra, was “to compose a set of songs without words” where “a poetic formal model would be turned into a musical formal model; and musical shapes would have to be found to correspond to this or that poetic object or idea, to this or that image or emotion or figure of effect.” Henze admits a need to spell out these connections–between words and music–in his earlier scores. Beginning with Liebeslieder however, he aims to free the listener from any need of finding intended parallels between his source material and the resultant music by concealing it altogether.

 In the instance of the String Quintet, the poem is one of the author’s own, taken from his collection Tide Marks a collaboration with the artist Alice Fox:

here alone apart
I realise

we are marked by the tide’s turn

and that drawing back
long aching inhalations
intakes of more than breath:
the very filling of lungs
with white and various
of beach
of foreshore
in the heavy air.

Its constantness,
its everywhere and together
though with such difference
scoured into the sand
by weather’s hand
by the wind’s rough play.

The entire rhythmic articulation by the chordal ‘trio’  of the second section of the score is created by applying the classical poetic metrics to this poem. The poem itself is divided into three sub-sections A, B and C. Here below is section A covering bars 48-55 with the text shown below the poetic metrics:


17-20Surrounding the rhythmic chordal material shown above first violin and cello weave a sequence of phrases. In the violin part two phrases are generated from a white-noise fractal to fit selected ranges shown in the vector-to-pitch conversion. The third phrase takes melodised material from the chordal parts played by violin and two violas:


17-22The opening duet between violin and cello in Section 2.

This pattern of phrases between violin and cello continues, becoming more and more adventurous rhythmically as the conclusion of the piece approaches. In the final section irrational rhythmics begin to appear. Here’s the code for the bars 74 to 92 of the violin part. Notice the use of pitch-ornament to avoid repeated pitches appearing in the violin part. In the generation of vectors from white-noise, a function vector-smooth provides further fine control over the vector output:


temp6The final 17 bars of first violin and cello parts of String Quintet.

The two score-files that make up this composition are considered to be a good practical limit to size and complexity of content. Larger files can make the inevitable debugging and checking difficult.

In contrast to the String Quintet here is a further quintet for a very different ensemble: piano and four percussion. Omphalos is a composition that explores the the use of six chord clusters ‘found’ at the keyboard, six rhythmic patterns and a six-note pattern taken from the Slonimsky Thesaurus. The score is through-composed in every detail using the Symbolic Composer CAC environment and is published with a full annotation of the code on the composer’s website archive. Below is a summary of the core material of the piece:

temp7In the opening bars of Omphalos it’s possible to see the way the chordal clusters played by the piano are occasionally melodised. In the percussion part each instrument takes just two rhythmic patterns:


In the second section of the piece the piano plays a continuous stream of patterns across two hands derived from the gen-hopalong algorithm. The ‘double’ output is then filtered to create just six pitches that when placed in a scalic form produce the Slonimsky pattern No.6. The percussion patterns that accompany this moto perpetuo are also continuous, though occasionally  interrupted by tutti rests, and quite differently patterned in each percussion part:

temp8In the music generated for the opening and closing sections there is a sequence of four long phrases each with different characteristics. For the opening section these characteristic begin with clusters, move to splitting some clusters into arpeggios, reversing the direction of some arpeggios, randomising octave positions of some arpeggios or chords, expanding or shuffling arpeggios. In the final section this ordering of characteristics is reversed, starting with the complex processing ‘expanding and shuffling arpeggios’, and gradually returning to the basic clusters. The extract below is from the final ‘chords with some arpeggios’ phrase:


Links and References
Alice Fox – Tide Marks
Nigel Morgan – Omphalos
Opusmodus – Website

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