Sackbut

A sackbut is a type of trombone from the Renaissance and Baroque eras, characterised by a telescopic slide that is used to vary the length of the tube to change pitch. Unlike the earlier slide trumpet from which it evolved, the sackbut possesses a double slide, with two parallel sliding tubes, which allows for playing scales in a lower range.

Records of the term "trombone" predates the term "sackbut" by two decades, and evidence for the German term "Posaune" is even older. "Sackbut", originally a French term, was used in England until the instrument fell into disuse in the 1700s; when it returned, the Italian term "trombone" became dominant. In modern English, an older trombone or its replica is called a sackbut.

An older instrument generally differs from modern trombones by its smaller, more cylindrically-proportioned bore, and its less-flared bell. The bell section was more resonant (since it did not contain the tuning slide and was loosely stayed rather than firmly braced to itself). These traits produce a "covered, blended sound which was a timbre particularly effective for working with voices,... zincks and crumhorns", as in an alta capella.

The revived instrument had changed in specific ways. In the mid-1700s, the bell flare increased, crooks fell out of use, and flat, removable stays were replaced by tubular braces. The new shape produced a stronger sound, suitable to open-air performance in the marching bands where trombones became popular again in the 1800s. Before the early 1800s, most trombones adjusted tuning with a crook on the joint between the bell and slide or, more rarely, between the mouthpiece and the slide, rather than the modern pair of parallel tuning slides on the bell curve, which prevent the instrument from flaring smoothly through this section. Older trombones also generally don't have water keys, stockings, a leadpipe, or a slide lock, but as these parts are not critical to sound, replicas may include them. Bore size remained variable, as it still is today.

The first reference to a slide instrument was probably trompette des ménestrels, first found in Burgundy in the 1420s and later in other regions of Europe. The name distinguished the instrument from the trompettes de guerre (war trumpets), which were of fixed length.

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