Closed construction (musical instrument construction)

Comparison between two tenor bass trombones: open construction (left), closed construction (right)

Closed construction (also traditional wrap or closed wrap ) describes a type of construction in musical instrument construction , especially with the trombone .

The term is used here to describe the way the quart valve bow is guided in a tenor bass trombone . With the closed construction, the pipe winds in several loops within the rear "main arch". As a result, sound and response change when using the quart valve due to the higher air resistance. In order to minimize this problem, the open design ( open wrap ) was developed in the 1980s , in which the quart valve arch is guided as straight as possible.