Alto trombone
A trombone pitched in E♭, a fourth higher than the tenor trombone.
What it means
The alto trombone is a trombone usually pitched in E♭, occasionally in F, making it a fourth higher than the more common tenor trombone. Its shorter slide and smaller bore give it a brighter, leaner sound and make the upper register easier to reach.
Structurally, the alto trombone differs from the tenor mainly in its shorter tubing and narrower bore, while the basic principle of the slide as tuning and playing mechanism remains the same.
Musical use
In the polyphonic trombone consorts of the Renaissance and Baroque, the alto trombone traditionally took the top voice of a three-part ensemble of alto, tenor, and bass trombones, making it a fixed component of the church and civic wind music of that era.
With the rise of the valve trumpet and the growing use of the tenor trombone for the upper register in the orchestra, the alto trombone declined in importance from the early nineteenth century onward and was replaced by the tenor trombone in many ensembles.
More recently the alto trombone has seen a revival: today it is used mainly in historically informed performance and in choral-symphonic contexts, where composers again deliberately draw on its bright tone color, and many professional trombonists master the alto alongside the tenor trombone.
Performance practice
When switching from tenor to alto trombone, you need to recalibrate your slide positions, since the shorter tubing means closer spacing between positions. Use the shorter distances deliberately for faster register changes in high passages, but take care not to force the brighter sound.