Despite the hugeness of the tuba, it still has the ability to blend with great subtlety, if properly scored.
This relates somewhat to the role of the tuba in most scoring. While it’s a powerful bottom end in a brass chorale, and an overwhelming color in a low brass unison, the average role of the tuba in most case is as a solidifier. Orchestrators add tuba staccato to double bass pizzicato, and get a firm, pointed articulation. Or a pedal tone will double the basses on an extended low note. In these and other cases, the tuba makes a perfect companion to the tone, not dominating unless asked. It’s best in these cases to have the tuba marked down a notch dynamically, to put it behind the sound instead of in front of it.
Why is the tuba so compatible? It goes back to yesterday’s tip of tuba being a whole-tube instrument. Its conical shape gives it a timbre that’s actually more similar to a horn than to the trombones. I’ll discuss that point more in a future tip. But for now, think of similarities in tone pointing to parallels of function. If a tuba sounds like a very big, low horn, then it may be used as such. In fact, in places where you might really want a horn solo, or a horn to support a line, but the pitch is too low to get that characteristic sound, then you are really thinking of a tuba, not a horn.
In the excerpt below from my legend for orchestra, Maui’s Fishhook, the tuba does some very delicate support of tremolo basses and cellos. Note the dynamic variance here – the tuba stays at pp throughout, while the lower strings start at p and swell. It doesn’t matter, though – the tuba cannot be drowned out, though it will be felt more than heard. The effect is an ominous hollowness behind the tremolo, as if looking into a cavern. This is complemented by the distant horn pad above (remember horn pads?). I remember scoring this, forgetting all about it, and then working with narrator at rehearsal and thinking “wow, those are some fat, freaky tremolos!” 😀