The Trombone Family
As with many instrument families, the trombone family has a range of different sizes and keys of instruments.
The most common member of the trombone family. Pitched in the key of Bb, the tenor trombone is the most popular due to its size, timbre, and projection—and comes in a variety of sizes (small, medium and large). Depending on its size and design, tenor trombones with and without F-attachments are equally common.
After the tenor trombone, the bass trombone is the most common member of the trombone family. The bass trombone has been a member of the family from the development of sackbut consorts in the 1500s and while in previous centuries was often in the key of F, is now pitched in the key of Bb. The bass trombone has a larger bore size than the tenor trombone (typically .562-.578″) to allow it respond easier in the lower register and usually has at least one—if not two—valves to enable it to navigate the lower register. The bass trombone typically has a darker and larger timbre than the tenor and while it is easier to play in the lower register, often has a more difficult response in the upper range.
The valve trombone is designed as a tenor trombone, typically in the key of Bb, but utilizes valves to change pitch versus a slide. It is a commonly used by trumpet, baritone/euphonium or other valved-brass instrumentalists doubling on trombone, as well as in many Latin American, European and other traditional music settings.
Pitched in the key of Eb, the alto trombone is not as common as tenor or bass but is still used in a variety of musical settings. Many orchestral works from the late classical and early-to-middle romantic periods were written for alto-tenor-bass trombone sections and many orchestras will use this instrumentation to this day. It is also a common solo instrument and is often found in trombone choirs due to its relative ease of play in the upper register and lighter sound.
Also known as slide trumpet, the soprano trombone is pitched in the key of Bb, and plays in the same register as Bb trumpet. The soprano trombone has become a very specialized instrument and is not commonly used.