The trombone is a predominantly cylindrical tube with two U-shaped bends and a flared bell at the end. The tubing is approximately cylindrical but contains a complex series of tapers which affect the instrument's intonation. As with other
brass instruments, sound is produced by blowing air through pursed lips producing a vibration that creates a
standing wave in the instrument. The detachable cup-shaped
mouthpiece is similar to that of the
baritone horn and closely related to that of the
trumpet. It has a
venturi: a small constriction of the air column that adds resistance, greatly affecting the tone of the instrument. The slide section consists of a
leadpipe, inner and outer slide tubes, and bracing, or "stays". The soldered stays on modern instruments replaced the loose stays found on
sackbuts (medieval precursors to trombones). The most distinctive feature of the trombone is the slide that lengthens the tubing and lowers the pitch (cf.
valve trombone). During the
Renaissance, sleeves (called "stockings") were developed to decrease friction that would impede the slide's motion. These were soldered onto the ends of the inner slide tubes to slightly increase their diameter. The ends of inner slides on modern instruments are manufactured with a slightly larger diameter to achieve the same end. This part of the slide must be lubricated frequently. The slide section is connected to the bell section by the neckpipe and a U-bend called the bell or back bow. The joint connecting the slide and bell sections has a threaded collar to secure the connection. Prior to the early 20th century this connection was made with friction joints alone. Trombones typically have a short tuning slide in the U-shaped bend between the neckpipe and the bell, a feature designed by the French maker François Riedlocker in the early 19th century. It was incorporated into French and British designs, and later into German and American models, although German trombones were built without tuning slides well into the 20th century. This configuration places the tuning slide, which must be cylindrical, in a section of the tubing that is otherwise slightly conical. In the early- to mid-20th century, manufacturers experimented with a "tuning in the slide" configuration, placing the tuning slide in the cylindrical main slide so the bell section can have an uninterrupted conical taper. Because it adds weight to the main slide and is difficult to align properly, this design was largely abandoned. Some trombone makers have begun using this design again, with improved manufacturing techniques and lighter materials. Many types of trombone also include one or more
rotary valves connected to additional tubing which lengthens the instrument. This extends the low range of the instrument and creates the option of using alternate slide positions for many notes. Like the trumpet, the trombone is considered a cylindrical bore instrument since it has extensive sections of tubing that are of unchanging diameter (the slide section must be cylindrical in order to function). Tenor trombones typically have a bore of (small bore) to (large or
orchestral bore) after the leadpipe and through the slide. The bore expands through the bow to the bell, which is typically between . A number of common variations on trombone construction are noted below.
Bells Trombone bells (and sometimes slides) may be constructed of different
brass mixtures. The most common material is yellow brass (70% copper, 30% zinc), but other materials include rose brass (85% copper, 15% zinc) and red brass (90% copper, 10% zinc). Some manufacturers offer interchangeable bells. Tenor trombone bells are usually between in diameter, with most being between . The smallest sizes are found on jazz trombones and older narrow-bore instruments, while the larger sizes are common on orchestral models. Bass trombone bells can be or more, with most being between . The bell may be made from two separate brass sheets or from one single piece of metal, hammered on a mandrel to shape it. The edge of the bell may be finished with or without a piece of bell wire to secure it, which also affects the tone quality; most bells are built with bell wire. Occasionally, trombone bells are made from solid
sterling silver.
Valve attachments Modern trombones are often constructed with a valve attachment, an extra loop of tubing attached to the bell section and engaged by a
valve operated by the left thumb by means of a
lever or trigger. The valve attachment aids in increasing the lower range of the instrument, while also allowing alternate slide positions for difficult music passages. A valve can also make
trills a lot easier. The valve attachment was originally developed by German instrument maker
Christian Friedrich Sattler in the late 1830s for the (), a B tenor trombone built with the wider bore and larger bell of a bass trombone that Sattler had earlier invented in 1821. Sattler's valve attachment added about of tubing to lower the fundamental pitch from B to F, controlled by a rotary valve, and is essentially unchanged in modern instruments. Valve attachments are most commonly found on the tenor and bass trombones. However, they can appear on sizes from soprano to contrabass, in different variety of keys, depending on the size of the instrument. ;Soprano :In the early 2010s Torbjörn Hultmark of the
Royal College of Music commissioned the first soprano trombone in B with an F valve, built by Thein Brass. ;Alto :Although rare on the E alto trombone, a valve attachment usually lowers the instrument a perfect fourth into B, providing the first five or six positions from the tenor trombone slide. Some alto models also have a valve called a
trill valve, providing a small loop of tubing that lowers the instrument by only a minor or major second, into D or D respectively. ;Tenor :Tenor trombones, especially the larger bore symphonic models, commonly have a valve attachment which lowers the instrument from B to F. :It provides access to the otherwise missing notes between the
pedal B in first position, and the second partial E in seventh, as well as providing alternate slide positions for other notes in long (sixth and seventh) positions. Because the attachment tubing increases the length of the overall instrument by one-third, the distances between slide positions must also be one-third longer when the valve is engaged, resulting in only six positions available on the F slide, to low C. Thus, the F attachment cannot provide the low B, but it usually has a sufficiently long tuning slide to lower it into E as required, which will provide B in a very long position. ;Bass : :The modern bass trombone usually has two valve attachments to provide all of the notes that are absent on an instrument with no valves (B – E). This allows the player to produce a complete
chromatic range upwards from the pedal register. :The first valve is an F attachment the same as that found on a tenor trombone and extends the range down to C. The second valve, engaged together with the first, lowers the instrument to D (or less commonly, E) and provides the low B. The second valve can be
dependent, where it serves to lower the F attachment to D and has no effect alone. More commonly the second valve is
independent, where it can be engaged separately to lower the instrument to G, or to D when both are engaged. :Single-valve B bass trombones with an F attachment are still made but are now less common than two-valve bass trombones. The single valved B bass trombones are essentially very large bore tenor trombones, and likewise are unable to provide the low B without lowering the valve to E with a long tuning slide. ;Contrabass : :Contrabass trombones in F typically have two independent valves, tuned either to C and D combining to A, or in European models tuned to D and B combining to A. Contrabass trombones in low B usually have only one valve in F, although Miraphone make a model in C with two independent valves in G and A, which combine to E.
Valve types The most common type of valve seen for valve attachments is the
rotary valve, appearing on most band instruments, as well as most student and intermediate model trombones. Many improvements of the rotary valve, as well as entirely new and radically different valve designs, have been invented since the mid 20th century to give the trombone a more open, free sound than the tight bends in conventional rotary valve designs would allow. Many of these new valve designs have been widely adopted by players, especially in symphony orchestras. The Thayer
axial flow valve is offered on professional models from most trombone manufacturers, and the
Hagmann valve particularly from European manufacturers. Some trombones have three
piston or
rotary valves instead of a slide; see
valve trombone.
Tubing F attachment tubing usually has a larger bore through the attachment than through the rest of the instrument. A typical slide bore for an orchestral tenor trombone is while the bore in the attachment is . The attachment tubing also incorporates a tuning slide to tune the valve separately from the rest of the instrument, usually long enough to lower the pitch by a semitone when fully extended (from F to E on tenor and bass trombones, to reach the missing low B). Valve attachment tubing is often coiled tightly to keep within the bell section (
closed wrap or
traditional wrap). A less coiled configuration, called
open wrap, is found on some 19th and early 20th century instruments. In the early 1980s, American instrument manufacturers began producing open wrap instruments after Californian instrument technician Larry Minick introduced open wraps around the same time that the
Thayer valve began to emerge among orchestral players. Open wrap F attachment tubing is shaped in a single loop free of tight bends, resulting in a freer response and more "open" sound through the valve. In marching bands and other situations where the trombone may be more prone to damage, the confined traditional wrap is more common, since open wrap tubing protrudes behind the bell section.
Tuning Some trombones are tuned using a mechanism in the slide section instead of a tuning slide in the bell section. Having the tuning slide in the bell section (the more typical setup) requires two sections of cylindrical tubing in an otherwise conical part of the instrument, which affects the tone quality. Placing the tuning mechanism in the cylindrical slide section allows the bell section to remain conical.
Slides Common and popular bore sizes for trombone slides are for tenor trombones, and for bass trombones. The slide may also be built with a
dual-bore configuration, in which the bore of the second leg of the slide is slightly larger than the bore of the first leg, producing a stepwise conical effect. The most common dual-bore combinations are , , , , for tenor trombones, and for bass trombones.
Mouthpiece The mouthpiece is a separate part of the trombone and can be interchanged between similarly sized trombones from different manufacturers. Available mouthpieces for trombone (as with all brass instruments) vary in material composition, length, diameter, rim shape, cup depth, throat entrance, venturi aperture, venturi profile, outside design and other factors. Variations in mouthpiece construction affect the individual player's ability to make a lip seal and produce a reliable tone, the
timbre of that tone, its
volume, the instrument's
intonation tendencies, the player's subjective level of comfort, and the instrument's playability in a given pitch range. Mouthpiece selection is a highly personal decision. Thus, a symphonic trombonist might prefer a mouthpiece with a deeper cup and sharper inner rim shape in order to produce a rich symphonic tone quality, while a
jazz trombonist might choose a shallower cup for brighter tone and easier production of higher notes. Further, for certain compositions, these choices between two such performers could easily be reversed. Some mouthpiece makers now offer mouthpieces that feature removable rims, cups, and shanks allowing players to further customize and adjust their mouthpieces to their preference.
Plastic plastic Instruments made mostly from plastic, including the pBone and the Tromba plastic trombone, emerged in the 2010s as a cheaper and more robust alternative to brass. Plastic instruments could come in almost any colour but the sound plastic instruments produce is different from that of brass. While originally seen as a gimmick, these plastic models have found increasing popularity of the last decade and are now viewed as practice tools that make for more convenient travel as well as a cheaper option for beginning players not wishing to invest so much money in a trombone right away. Manufacturers now produce large-bore models with triggers as well as smaller alto models.
Regional variations Germany and Austria German trombones have been built in a wide variety of bore and bell sizes. The traditional German
Konzertposaune can differ substantially from American designs in many aspects. The mouthpiece is typically rather small and is placed into a slide section with a very long leadpipe of at least . The whole instrument is typically made of gold brass. They are constructed using very thin metal (especially in the bell section), and many have a metal ring called a () on the rim of the bell. Their sound is very even across dynamic levels but it can be difficult to play at louder volumes. Since the mid-20th century, modern instruments use a trigger to engage the valve while playing. As with other traditional German and Austrian brass instruments, rotary valves are used to the exclusion of almost all other types of valve, even in valve trombones. Other features often found on German trombones include long
water keys as well as
Schlangenverzierungen (snake decorations) on the slide and bell U-bows to help protect the tubing from damage. Since around 1925, when jazz music became popular, Germany has been selling "American trombones" as well. Most trombones made and/or played in Germany today, especially by amateurs, are built in the American fashion, as those are much more widely available, and thus far cheaper. However, some higher-end manufacturers such as Thein make modern iterations of the classic German
Konzertposaune, as well as American-style trombones with German features like the
Kranz and snake decorations.
France French trombones were built in the very smallest bore sizes up to the end of the
Second World War and whilst other sizes were made there, the French usually preferred the tenor trombone to any other size. French music, therefore, usually employed a section of three tenor trombones up to the mid–20th century. Tenor trombones produced in France during the 19th and early 20th centuries featured bore sizes of around , small bells of not more than in diameter, as well as a funnel-shaped mouthpiece slightly larger than that of the
cornet or
horn. French tenor trombones were built in both C and B, altos in D, sopranos in F, piccolos in B, basses in G and E, and contrabasses in B. == Types ==