Tool #5: Orchestrating Those Low Frequencies


After Tool #4’s drier atmosphere, I figure it is time to return to more savory compositional topics.  I’d like to talk about muddiness, darkness, and low frequencies, particularly relating to low-frequency-producing instruments.

As we orchestrate as part of composing, we often might want a clear, intelligible sound from our large ensemble writing.  (Unclear, unintelligible sound has its place, but let’s stick to a more focused sound as our target for the present purposes.)  How do we keep those lower frequencies in check?  How do we prevent muddiness, and create complementary sounds that enhance the bass while not obscuring it?

One component is intervals.  Larger intervals such as the octave and perfect fifth are great for low frequencies.  It is very common to have the celli and basses playing in rhythmic unison one octave apart.  This isn’t just to make things playable: it also creates a clear, focused sound that can serve as a bass line, harmony, melody, or other function.  In my bassoon and contrabassoon writing, I like to double at the octave to get the timbre of the two instruments while still having focus.  It is taught in orchestration class that the octave, perfect fifth, and perfect fourth are the staples of writing low brass parts, and intervals wider than these work well too.  This is because one can hear the individual notes, harmony, and blended timbre all together in a focused, intelligible sound.

Another component is register of the instrument.  That low buzz of the bass trombone will sound more unfocused than if it were notated as higher pitches.  That low F on the E string of the basses will sound more focused an ocatve up.  The key element here is knowing the sound you want, and going for it.  If you want a droning G on the low E string of the basses for an rather unfocused effect, go for it!  Just know that register of each instrument affects the focus of that instrument and the ensemble in which it is a part.

We are currently talking about ensemble writing, so let’s investigate instrument complements.  If you have the basses on a low E string having eighth note hits on the downbeat, you might not need to change that timpano from F# to a low E.  The unfocused sound of the lowest timpano might cover up the difference in pitch.  In this case your goal might be going for a “low sound hit”, and the basses and timpano might be able to get it done without making the timpanist retune.  Use percussion to reinforce the frequencies (but not too much if you don’t want to be overwhelmed with low frequencies).  A bass drum can add in the low punches to the hits created by the low-frequency instruments.  Experiment with tom-toms or other drums to add to the effect.  Organize your trombones to complement the higher-up trumpets; they are both cylindrical-bore instruments, and work well together.  The same pairing occurs between the conical-bore tubas and french horns.

Still, you have to watch out for too much bass.  This occurred a little in one part in my orchestral piece Shards, where the low brass and bass drum hits were too loud.  A simple dynamic change or having fewer instruments holding the bass line can reduce overpowering volume, noise, and free up the instruments for other uses.  Texture is also important in this regard.  Too many bass lines will create confusion, and the simpler low passages generally are the clearest.

What are your thoughts–what works best for you?

Thanks for visiting, and come back frequently; there’s so much to discuss!

Dan

One thought on “Tool #5: Orchestrating Those Low Frequencies

  1. I spend most of my workday arranging showband and big band music, with some occasional theater stuff thrown in. So although my experience in orchestral music is limited, I think it’s safe to say that the physics works the same. My first arranging teacher hammered at the importance of using the harmonic overtone series to find the acoustical root of the chord when compiling my harmonic “stacks”. When the bass is on the root, it’s fairly easy to count down. When the bass is on another note, it’s a bit more difficult, but with a bit of practice you learn to see them pretty fast. Any interval with an acoustic root below 27.5 is going to create some mud. Some instruments (Bari sax? Cello?) have such strong, fabulous overtones, that it’s hard to give them too much space of their own. Often, I won’t put anything closer to the Bari than maybe a tenth or twelfth, and the results are almost always for the better.
    Great forum, BTW. Keep it up!
    David Schindler
    Toronto

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