Bass tuba - Sound production
Overall the embouchure is relaxed; it is only in the high register that the lips are tensed.
Pedal tones (1st naturals) speak well on all conical instruments, although on the tuba they require an enormous amount of effort on the part of the player. Theoretically all the pedals (from F1–Gb0) can be played, but the huge demands made on the breathing mean that this is barely possible in practice: the bigger the instrument, the more difficult it is to play in the pedal region.
The number of steps by which the valves can lower the first pedal note depends on how wide the bore is: on narrower-bore tubas it is four semitones (to Db1), on instruments with a wider bore it is eight semitones (to A0). Lower notes can no longer be played and are used only from the 2nd natural.
The tuba’s fast rate of flare allows overblowing only as far as the 8th natural, except on narrower-bore tubas in F, on which the 9th and 10th naturals can be produced with the help of an appropriate mouthpiece.
On tubas the ratio between bore profile and bell diameter is not constant. A tuba with a narrow bore can have a very wide bell and vice versa. This ratio is usually expressed as a fraction with the denominator 4, e.g. bass tuba in F: 4/4 size or 3/4 size. Bore profiles range in size from 3/4 to 7/4.
As a rule lower-pitched instruments have a less agile and therefore slower response than higher-pitched ones. It takes longer for the column of air in the tube to respond. Tuba players have to compensate for this late response, which they do by beginning their attack prematurely - they must continually jump the gun, as it were, and remain fractionally ahead of the conductor.
A further difficulty encountered by tuba players is the fact that they sit right at the back of the orchestra amid curtains or surfaces that absorb part of the instrument’s sound. Their proximity to the timpani has a similar effect, because some of the tuba’s overtones are swallowed by the sound of the timpani.
The bass tuba’s range is the same as that of the contrabass tuba, which means that all the pieces commonly performed today could be performed by the bass tuba. The lowest notes are equally hard to produce on both instruments. However, the even greater richness of tone and darker timbre of the contrabass tuba mean that it is preferred for parts at this pitch level.