The Structure of the Horn
The structure of the horn

These sound more like mattress sizes, but single, double, and triple are the names of the various horn structures. The two big categories are the single horn and double horn, and within the single horn group there is the F horn, B♭horn, and high-F horn, that plays one octave above the F horn. The F horn has an effective length of 360 cm when none of the levers are depressed, while the B♭horn is 270 cm, and the high-F, 180 cm. The longest horn is the F horn, and it has the lowest tonal range.
A double horn is an instrument with two tubes of different pitches. Most commonly, a double horn consists of an F tube and a B♭tube.
A "descant double" has a B♭tube and a high-F tube, and in this case, descant means "high pitched tone."
A triple horn has all three pipes: F, B♭, and high-F tube. The appearance of the horn also changes as the number tubes increases. Let's listen to the tone of the F and B♭horns.

On the left is a semi-double horn, on the right, a full-double. Though these two have the same range, they are built differently.

The total length of the tube is a little shorter on the semi-double. The diagram below shows the length of the tubes and the position of the three valves. The valves on a horn are arranged in two tiers, but for simplicity's sake they are evenly spaced.

Full-double and semi-double horn structure

A tube length of 275 cm is necessary to produce a low B♭, and the lower F requires a tube length of 370 cm.
On the full-double horn, the air can flow through either the B♭ branch or the F branch. However, the B♭ branch is 30 cm long, which leaves a tube of 245 cm (275 minus 30) that is also used when playing the low F. This means that the F branch must be 125 cm long (370 - 245).

In contrast, on the semi-double horn, a 275 cm tube, which is required to play the low B♭, is the primary tube on the instrument. To play a low F, air flows through the F branch, returns to the beginning, and passes through the entire length of the 275 cm tube. In other words, the F branch must be 95 cm long (370 minus 275), which is 30 cm shorter (125 minus 95) than the full-double.
Compared to the full-double horn, the semi-double horn is 0.1 to 0.2 kilograms lighter. However, there are drawbacks. When playing the low F, the air passes the valve section of the F tube and then passes the valve section of the B♭ tube. This means that air has to pass many uneven spots inside the tube, which has an effect on the tone.
The first semi-double and full-double horns were created by famous horn makers such as Alexander and Kruspe around 1900. Below is a list of the names of all the parts of the full double horn.

Names of the parts on the F/B♭ double horn

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The entire display

Click on the names of the parts/option> Bell First tube Leadpipe Mouthpiece Neck strap ring Bell screw Main tuning slide First rotary valve Second rotary valve Third rotary valve Fourth rotary valve F tube first slide F tube second slide F tube third slide B♭ tube first slide B♭ second slide B♭ tube third slide First lever Second lever Third lever Fourth lever (for switching between F and Bb)

Select any name to zoom in on the part.

Hand-stopping is one of the techniques that is unique to the horn, and that is used to change the pitch of the instrument.
However, sometimes the pitch becomes slightly higher, and there is no appropriate alternate fingering. Thus, the B♭single horn and the B♭/High F descant double horn has an extra valve to alter the pitch slightly, called a "gesttopft key."

The horn, like other members of the brass family, is made from yellow brass, which has a yellow-gold color, or from gold brass, which has a reddish-gold color. However, the horn's body is sometimes made from nickel silver, which is another characteristic unique to the horn. A horn made entirely from nickel silver is quite impressive.

Two reasons for the very different timbre of the Vienna horn from normal horns with rotary valves are the narrower (11mm) bore size of the Vienna horn and the taper of the bell and mouthpiece, which are nothing like those of the standard horn. In addition to those differences, a different valve system and the presence of a bogen also have an impact.
The final important point of difference is that while the Vienna horn is fundamentally in F, normal horns are most often double and triple horns are in B flat.

A clutch valve is a valve that is opened or closed manually. In contrast to a more standard valve that is operated by a lever and is returned to its original position by a spring, a clutch valve stays open when it has been opened, and stays closed when it has been closed.