Organ pipe
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An organ pipe is a sound-producing element of the
Construction
Materials
Organ pipes are generally made out of either
Metal
Metal pipes are usually made of
.Metal pipes are generally made by first
Wood
The body of a wooden pipe can be made of either a coniferous wood (softwood) or hardwood, although the lower section of the pipe (comprising the metal foot (on some pipes), cap, block and mouth) will nearly always be made from hardwood to provide a precise edge for the pipe's mouth. Using screws and glue, the pipes are assembled from wooden pieces of various shapes and sizes. In contrast with the circular cross-section of a metal pipe, the cross-section of a wooden pipe is most commonly square or rectangular.
Glass
Glass pipes have been created using warm glass and stained glass techniques by Xaver Wilhelmy. Three Wilhelmy glass ranks exist in the United States, two in a private collection in West Virginia and one in a private collection in Virginia. The image at left shows the Wilhelmy American Flag Glass Pipe Organ that was created as a part of a Memorial Proposal for Ground Zero after the events of September 11, 2001.[1]
Shapes
The bodies of organ pipes are generally made in three shapes: cylindrical, conical, or rectangular. Cylindrical pipes are simple
The end of the pipe opposite the reed or mouth may be either open or closed (also known as stopped). A
Certain organ pipes are also mounted horizontally in the shape of a trumpet horn so as to project the sound farther. These pipes are known as en chamades. However, when such a commanding tone is desired but it is impossible to mount an en chamade on the case, a hooded reed is used. This type of pipe stands vertically and has a 90-degree bend at the top which acts to project the sound outward in the same way an en chamade does, but can be placed in the interior of an organ.[2]
Pitch
The pitch produced by an organ pipe is determined in two fundamentally different ways. For a reed pipe it is determined mainly by the mechanical properties of the reed and the length of the protruding part. For the flue pipes it is determined by the shape of the air column inside the pipe and whether the column is open at the end. For those pipes the pitch is a function of its length, the wavelength of the sound produced by an open pipe being approximately twice its length. A pipe half the length of another will sound one octave higher. If the longest pipe, C, is 8 feet (2.4 m) in length, the pipe one octave higher will be 4 feet (1.2 m) long, and two octaves above (middle C) will be 2 feet (0.61 m) long. A closed (stopped) pipe produces a sound one octave lower than an open pipe. For example, a stopped pipe 4 feet (1.2 m) long will produce the same pitch as an open pipe 8 feet long: two octaves below middle C.
The nomenclature of a rank of pipes is based on the size of an open pipe that would produce the same pitch, regardless of the type or size of the actual pipes in the rank. For example, a rank of open pipes labeled as 8′ (pronounced "eight-foot") would have a pipe for C two octaves below
Varieties
Flue pipes
The sound of a flue pipe is produced with no moving parts, solely from the vibration of air, in the same manner as a
Flue pipes generally belong to one of three tonal families: flutes, diapasons (or principals), and strings. The basic "foundation" (from the
The different sounds of these tonal families of pipes arise from their individual construction. The tone of a flue pipe is affected by the size and shape of the pipes as well as the material out of which it is made. A pipe with a wide diameter will tend to produce a flute tone, a pipe with a medium diameter a diapason tone, and a pipe with a narrow diameter a string tone. A large diameter pipe will favor the fundamental tone and restrict high frequency harmonics, while a narrower diameter favors the high harmonics and suppresses the fundamental. The science of measuring and deciding upon pipe diameters is referred to as pipe scaling, and the resulting measurements are referred to as the scale of the pipe.
Reed pipes
The sound of a reed pipe is produced by a beating
By altering any of several parameters (including the shape and volume of the resonator, as well as the thickness and shape of the reed), a reed pipe can produce a wide variety of tonal colors. This allows reed stops to imitate historical musical instruments, such as the
Free reed pipes
These are quite uncommon; see "Free reeds" in the "Reed pipe" article.
Diaphone pipes
The diaphone is a unique organ pipe. Uncommon in church and concert pipe organs, they are quite common in Theatre Organs. Invented by
The Diaphone pipes are used for the bottom 12 or 18 notes of the 16' Diapason rank, and also for its bottom 32' octave, on those few Theatre Organs that go that low.
Hope-Jones also developed an imitative version of the diaphone called the diaphonic horn, which had a more reed-like quality than the diaphone and was voiced on lower wind pressures.
See also
References
- ^ "World Trade Center Site Memorial Competition". Archived from the original on 2013-10-05. Retrieved 2013-10-04.
- ^ "Pipe Construction". Archived from the original on 2019-03-03. Retrieved 2019-03-13.