Orchestrators must be mindful of the amount of breath required to sustain a note or phrase on the tuba.
Tuba can be a surprisingly agile, even delicate instrument, capable of great subtlety and range of expression. It’s in some ways the opposite of the bass trombone in the same lower registers. Some composers have used this to great advantage, like Prokofiev who we’ll look at later this week.
One thing that a tuba player does not possess is unlimited amounts of breath. The louder the note, the more force is being applied to the embouchure, and the more breath being used. This brings the orchestrator’s plans for a low pedal point on tuba into immediate conflict with reality. A tuba player simply cannot hold down the same low note for minutes at a time, especially in very loud passages.
As usual, the great masters can prove enlightening by their example. For instance, Rimsky-Korsakov’s orchestration of Mussorgsky’s “Night on Bare Mountain” has a few pedal points at mf for tuba, which last only 6 bars at a fast tempo, and are divided into two groups of three bars. The tuba player can easily take a breath in the middle if needed.
In the excerpt below from “Also Sprach Zarathustra” by Richard Strauss (after fig. 16), the music is going full-bore, with a low C pedal point on bass tuba at ff for 10 bars. Strauss accomplishes this by breaking the ties into 2-bar sections, overlapping 2-bar sections with contrabassoon on the same note. Then he adds some support with the phenomenally low-pitched 2nd horn, doubling the note in old-notation 3rd-ledger-line G below the staff. With the timpani roll on the next C up, the tradeoff becomes seamless to the ear.
Even with frequent breaths, it’s not good to score pages and pages of this kind of playing for the tuba. That would be an unimaginative waste of a great instrument.