Recently, I've undertaken some large engraving projects - I'm making clean versions of the Tchaikovsky ballets. This may seem a little silly at first, but having spent a good deal of my playing career in the pit, I grew frustrated with looking at music that was published only with the publisher's bottom line in mind (too much musical information crammed in a small space to save paper), and wasted rehearsal time while the orchestra tried to figure out where the conductor wanted the orchestra to begin (no rehearsal numbers, too few rehearsal letters, inconsistent titles and labels for scenes and movements).
A few other publishers have also undertaken these projects, and while they have included rehearsal numbers and modern transpositions, I still haven't seen a set of parts published with the people who actually make the sound in mind. Pits are dark and cramped - white paper please and bigger notation for old, tired eyes.
I digress. The reason I brought up these engraving projects - there is an ulterior motive for doing these projects. Every time I work on a music notation project (arranging, orchestrating, engraving, copy work, etc), is an opportunity to learn from a master. Sometimes it also means learning what NOT to do, but those instances are far fewer.
My objective today is to discuss what I previously identified as the fourth texture (see 4 Dimensional Texture). That is providing contrast in your arrangement or orchestration using any or all of the chamber music groups that are subsets of your ensemble.
I could list all the possible combinations contained within a brass ensemble, but with just a little imagination, anyone can do that. Don't forget the smallest combinations (any two instruments in your ensemble). But the main point is, each of these small(er) combinations is a tone color and the use of them can provide not only tone color contrast within your scores, but also contrast in volume and density.
Igor Stravinsky's Rite of Spring is written for a huge orchestra. Large string and percussion sections, and 5 of everything else. But the first several minutes of his score for huge orchestra is purely chamber music. Measure number 39 is the first instance where he colors one sound with another, and this even sparingly (cello pizz and alto flute reinforcing alternating notes of a bass clarinet triplet). It is not until measure 62 that he uses much of the ensemble on hand to add weight, compound colors, and density to his score. And it's only 4 measures, and then right back to chamber music. Rehearsal number 34 is the first instance where he has most of the orchestra busy at the same time - that is just the last 12 measures of the second section of his form.
This is an awesome display of restraint, and orchestration with intent.
Most music comprises only a few ideas when distilled down to notes and rhythms. Sometimes those individual ideas are homophonic - a harmonized melody, and/or chordal accompaniment figure - but I would suggest even this example is just 2 ideas.
A quick glance at rehearsal 34 in Stravinsky's own distillation for 2 pianos of Rite of Spring reveals that this very dense and complex page of orchestral score is only 4 basic ideas (the full score of the first 4 measures of rehearsal 34 is the featured image above this post). Even the 2 inner voices are similar ideas.
It is important to understand the context for which music is scored. In this case, one could argue (and I think be correct) that Stravinsky wasn't attempting to create a performance score for 2 pianos of his masterpiece, but rather a distillation of basic elements - particularly rhythmic - with which a ballet company could rehearse without the prohibitive expense of hiring an orchestra for every rehearsal. In other words, this version had a practical purpose, and limited by what can be accomplished by 20 digits and a single tone color.
Quite by accident, this passage is for 11 voices and here rendered (without skill or creativity) for the Boulder Brass instrumentation:
Phil Snedecor has masterfully arranged the entire First Part of Rite of Spring for large brass ensemble (Washington Symphonic Brass - 444.01) and that arrangement can be found by clicking here.
I've strayed a bit off topic - but the point is: use your entire ensemble with intent. That means all sets and subsets are at your disposal to create variety and contrast.