The qualities of instrumental color should dictate the development of thematic material in a orchestral score.

This, I feel, is one of the hardest things for a beginning orchestrator to grasp. Very often, I’m seeing beginning scores where thematic development is very pianistic, and of course that’s natural as most composers nowadays are pianists or have learned about form in the context of the piano sonata. Well and good. Here’s the problem – name one piano sonata in the standard recitalist’s repertoire that has been successfully adapted to become standard symphonic repertoire. And of course, there aren’t any. The reason why is not just because of scope or placement of harmonic elements.

Pianistic writing assumes that the same basic timbre is being used throughout the piece. Therefore, aside from certain variations of dynamics and register, the composer must engage us intellectually to hold our interest. That great strength of solo piano composition turns into a great weakness in orchestral scoring. It all goes back to Monday’s tip – a well-written orchestral phrase must fit the instrument like a glove, and reveal the potential within it. Otherwise, your musician is just playing an arbitrary line of music that might work on any instrument, but not work very well. You cannot count on a pianistic phrase being successful on a different instrument – sometimes it works, like with Bach or Ravel – but most often not.

Yesterday I wrote about thematic exposition having the form of a paragraph, or short narrative. Today, I want you to think of orchestral thematic development as a conversation, in which those who pick up the subject make the most sense of it within their own frame of reference and strength of expression, rather than just blockheadedly repeating whatever they’re told.

That is the essence of function. I’ve defined the separate elements of orchestration as texture, balance, and function – function being the linear element, that is, what is actually happening. In an orchestral setting, musical function has to be tied to the tonal and expressive possibilities that are unique to its performers; but more than that, function must be driven by the instruments. The development of thematic material must be opened up and explored, even dictated by the interactions and contrasts.

So stop telling the instruments what to do – and start allowing them to tell you what they need to do.

In the excerpt below from the first movement of my harp concerto, the harp is echoing the third theme, which was just introduced by the horns. This leads back to a short development section in which the first theme works its way through several different settings, to a rising harmonic accompaniment, starting with the first violins at bar 70. This is echoed by the bass trombone at mf in its most secure register, with the phrase completed by the first clarinet in its pungent third octave. Note how at this point, the strings crescendo up a bit to meet the new dynamic level, while under them the horns and bassoon start to back them up with a pad. Finally, the timpani doubled by bass clarinet make the final statement, with a little swell under the upper wind commentary as the rest of the orchestra fades. The cumulative result is that this little section of imitation explored the theme over various ranges of instruments and modalities, bringing the introduction of the third theme to a close, and bridging to a further exploration of the first theme in the solo harp, about to start on the next page. This was definitely a case of letting the instruments decide what to do next, rather than forcing an unnatural scheme onto them.

Orchestration - Instrumental Color Dictating Thematic Development