Bass trombone - Sound production
The tenor-bass and bass trombones have the widest range of all wind instruments.
The natural harmonic series from the 1st to the 12th natural is generally used. Pedals are also part of the instrument’s range. From the 20th century it has been usual for pedal notes to be played on the trombone. These are especially easy to play on the bass trombone because of its wider bore.
As with the tenor trombone 7 positions (slide lengths) are playable in the Bb tuning (valves closed). Each position lowers the natural harmonic series by a half tone.
With the fourth-valve
Six positions are playable in the F tuning (fourth-valve open).
With the third-valve
Five positions are possible in the D tuning (third-valve open).
In the shortest (1st) position the tube length of the Bb tuning (closed valves) is 290 cm.
In the D tuning (third-valve open) the tube length is 563 cm in the longest possible (5th) position. So when playing the lowest note on the bass trombone the musician has to vibrate an air column which is 5,6 m long!
Generally tenor-bass trombones are used as tenor trombones above C2 (valves closed) and as bass trombones (fourth-valve or fourth-valve and third-valve open) below it. Playing with open valves alters the instrument’s timbre.
The gap between Bb1 and E2 that exists on the tenor trombone between the 1st position’s pedal (Bb1) and the 2nd natural at the 7th position (E2) is bridged on the bass trombone with the aid of the fourth-valve and third-valve. The instrument is thus rendered fully chromatic. The problematical notes B1 and C2, which would not be playable with a fourth-valve alone, can be sounded easily and well by operating the third-valve. These notes were called for in older scores and could be played with ease on the old bass trombone.