Organ pipe
Encyclopedia
An organ pipe is a sound-producing element of the pipe organ
Pipe organ
The pipe organ is a musical instrument that produces sound by driving pressurized air through pipes selected via a keyboard. Because each organ pipe produces a single pitch, the pipes are provided in sets called ranks, each of which has a common timbre and volume throughout the keyboard compass...

 that resonates
Resonator
A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical...

 at a specific pitch when pressurized air (commonly referred to as wind) is driven through it. Each pipe is tuned to a specific note of the musical scale
Musical scale
In music, a scale is a sequence of musical notes in ascending and descending order. Most commonly, especially in the context of the common practice period, the notes of a scale will belong to a single key, thus providing material for or being used to conveniently represent part or all of a musical...

. A set of organ pipes of similar timbre
Timbre
In music, timbre is the quality of a musical note or sound or tone that distinguishes different types of sound production, such as voices and musical instruments, such as string instruments, wind instruments, and percussion instruments. The physical characteristics of sound that determine the...

 tuned to a scale is known as a rank or a stop
Organ stop
An organ stop is a component of a pipe organ that admits pressurized air to a set of organ pipes. Its name comes from the fact that stops can be used selectively by the organist; some can be "on" , while others can be "off" .The term can also refer...

.

Materials

Organ pipes are generally made out of either metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 or wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

. Very rarely, glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

, porcelain
Porcelain
Porcelain is a ceramic material made by heating raw materials, generally including clay in the form of kaolin, in a kiln to temperatures between and...

, plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

, paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

, Papier-mâché
Papier-mâché
Papier-mâché , alternatively, paper-mache, is a composite material consisting of paper pieces or pulp, sometimes reinforced with textiles, bound with an adhesive, such as glue, starch, or wallpaper paste....

, or even stone
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

 pipes may be seen. A historical organ in the Philippines has pipes made exclusively of bamboo.

Metal

Metal pipes are usually made of an alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

 of lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 and tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

, along with trace amounts of antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...

 and copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 for increased rigidity. The percentage of each metal in the alloy depends on the desired characteristics of the resulting pipe. The more lead used in the alloy, the darker the resulting tone will be. Conversely, if a pipe has a high proportion of tin, it will have a brighter tone. In addition, high amounts of tin give a gleaming and long-lasting polish, which may be desired if the pipe is clearly visible. The cost of each metal is also a factor, as tin is more expensive than lead. The usual exceptions to tin-lead alloys are very lowest pipes in a rank, which are sometimes made of rolled zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

. In addition, pipes have been made of many metals, including copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 electroplate, silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...

, brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...

, and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

.

Metal pipes are made by first casting a metal alloy of the desired metallurgical composition onto a long flat surface. Once the metal cools, it is cut into pieces, which are then rolled into shapes around molds called mandrel
Mandrel
A mandrel is one of the following:* an object used to shape machined work.* a tool component that grips or clamps materials to be machined.* a tool component that can be used to grip other moving tool components.- Variants :...

s and soldered together. Thus, the cross-section of a metal pipe is usually circular.

Wood

The body of a wooden pipe can be made of either a coniferous wood or hardwood, although the lower section of the pipe (comprising the foot, 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.

Shapes

The bodies of organ pipes are generally made in three shapes: cylindrical, conical, or rectangular. Cylindrical pipes are simple cylinders
Cylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...

, while conical pipes are in the shape of a tapering or expanding cone
Cone (geometry)
A cone is an n-dimensional geometric shape that tapers smoothly from a base to a point called the apex or vertex. Formally, it is the solid figure formed by the locus of all straight line segments that join the apex to the base...

. Rectangular pipes form cuboid
Cuboid
In geometry, a cuboid is a solid figure bounded by six faces, forming a convex polyhedron. There are two competing definitions of a cuboid in mathematical literature...

 shapes with either a square
Square (geometry)
In geometry, a square is a regular quadrilateral. This means that it has four equal sides and four equal angles...

 or rectangular
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The term "oblong" is occasionally used to refer to a non-square rectangle...

 cross-section when viewed from above. There are some irregular shapes as well: the Flûte triangulaire, for example, has a triangular
Triangle
A triangle is one of the basic shapes of geometry: a polygon with three corners or vertices and three sides or edges which are line segments. A triangle with vertices A, B, and C is denoted ....

 cross-section when viewed from above). In addition, a cylindrical or rectangular pipe can be tapered: that is, it can be made to be wider at the bottom than at the top. The internal shape of the pipe is a major factor in tone color.

The end of the pipe opposite the reed or mouth may be either open or closed (also known as stopped). A closed flue pipe
Closed tube
In the field of acoustics, a tone is created by the periodic vibrations of air applied to a resonator. There are several ways in music to create such vibrations. One of these is to use a closed tube and to blow across the end. This creates a Bernoulli, or "siphon", effect just below the open end or...

 with a uniform cross-section sounds an octave lower than a similar open pipe
Open tube
In the field of acoustics, a tone is created by the periodic vibrations of air. There are several ways in music to create such vibrations. One of these is to use a tube and to blow across the end. This creates a note of a given frequency, depending on the length of the tube and the pressure of the...

 of the same length. Also, such an open pipe produces a tone in which both the even-numbered and the odd-numbered partials
Harmonic series (music)
Pitched musical instruments are often based on an approximate harmonic oscillator such as a string or a column of air, which oscillates at numerous frequencies simultaneously. At these resonant frequencies, waves travel in both directions along the string or air column, reinforcing and canceling...

 are present, while a stopped pipe, such as a gedackt
Gedackt
Gedackt is the name of a family of stops in pipe organ building. They are one of the most common types of organ flue pipe. The name is a German word, meaning "capped" or "covered".- History :...

, produces a tone with odd-numbered partials. The tone of a stopped pipe tends to be gentler and sweeter than that of an open pipe, though this is largely at the discretion of the voicer.

Pitch

For more about the pitch of organ stops, see Organ stop: Pitch and length.

The pitch produced by an organ pipe 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
Octave
In music, an octave is the interval between one musical pitch and another with half or double its frequency. The octave relationship is a natural phenomenon that has been referred to as the "basic miracle of music", the use of which is "common in most musical systems"...

 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 foot (0.6096 m) long. A closed (stopped) pipe produces a sound one octave lower than an open pipe. For example, the lowest Gedackt
Gedackt
Gedackt is the name of a family of stops in pipe organ building. They are one of the most common types of organ flue pipe. The name is a German word, meaning "capped" or "covered".- History :...

 / closed C pipe (2 octaves below middle C) will be 4 feet (1.2 m) long.

The nomenclature of a rank of open pipes (for example an "8 foot" (8 feet (2.4 m)) Open diapason) refers to the length of the longest pipe in the rank. Thus the longest pipe, (C, two octaves below middle C
Middle C
C or Do is the first note of the fixed-Do solfège scale. Its enharmonic is B.-Middle C:Middle C is designated C4 in scientific pitch notation because of the note's position as the fourth C key on a standard 88-key piano keyboard...

) is 8 feet (2.4 m) long. An 8 ft (2.4 m) stop sounds at unison pitch, like a piano. In a rank of stopped pipes, the lowest pipe is 4 feet (1.2 m) in length but sounds at unison pitch, so it is known as an 8' stop.

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 recorder
Recorder
The recorder is a woodwind musical instrument of the family known as fipple flutes or internal duct flutes—whistle-like instruments which include the tin whistle. The recorder is end-blown and the mouth of the instrument is constricted by a wooden plug, known as a block or fipple...

 or a whistle
Whistle
A whistle or call is a simple aerophone, an instrument which produces sound from a stream of forced air. It may be mouth-operated, or powered by air pressure, steam, or other means...

. Wind from the "flue", or windway is driven over an open window and against a sharp lip called a Labium. By Bernoulli's principle
Bernoulli's principle
In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy...

 this produces a lower pressure region just below the window . When the vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

 under the window is large enough, the airstream is pulled under the Labium lip. Then the process works in reverse, with a low pressure region forming over the Labium which pulls the airstream to the other side again. This 'fluttering' airflow creates high and low pressure waves within the pipe's air column. A high and a low pressure wave form a single "cycle" of the pipe's tone. (See Wind Instrument
Wind instrument
A wind instrument is a musical instrument that contains some type of resonator , in which a column of air is set into vibration by the player blowing into a mouthpiece set at the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of...

.)

Flue pipes generally belong to one of three tonal families: flutes, diapasons (or principals), and strings. The basic "foundation" (from the French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 term fonds) sound of an organ is composed of varying combinations of these three tonal groups, depending upon the particular organ and the literature being played.

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
Organ flue pipe scaling
The subject of this article is technical in nature and requires an understanding of organ terminology. This is in the process of being rectified. Many of the terms used here are defined in the pipe organ article....

, and the resulting measurements are referred to as the scale of the pipe. Ranks of all three tonal families can be either open or stopped, although flutes are by far the most common of the three to be stopped.

Reed pipes

The sound of a reed pipe is produced by a beating reed: wind is directed towards a curved piece of brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...

 (the reed). A partial vacuum is created by higher velocity air flowing under the Reed which causes it to be pulled closed against a hard surface called the shallot. This shuts off the vacuum and allows the Reed to spring open again. A tuned resonator
Resonator
A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical...

 extends above this assembly and reinforces the sound produced. The principle is the same as that of the orchestral clarinet
Clarinet
The clarinet is a musical instrument of woodwind type. The name derives from adding the suffix -et to the Italian word clarino , as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed...

. The pitch of a reed pipe is determined primarily by the length of the reed but the cubic volume of air in the resonator supports that frequency. Most Reed pipes have a slide to adjust the vibrating length of the Reed to fine tune it. Because of the precision required in the making of the vibrating reed,resonator pipe and its accompanying parts, reed pipes are more complicated to manufacture than flue pipes.

By altering any of several parameters (including the shape and cubic 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 krumhorn
Crumhorn
The crumhorn is a musical instrument of the woodwind family, most commonly used during the Renaissance period. In modern times, there has been a revival of interest in Early Music, and crumhorns are being played again....

 or the regal
Regal (musical instrument)
The regal was a small portable organ, furnished with beating reeds and having two bellows. The instrument enjoyed its greatest popularity during the Renaissance. The name was also sometimes given to the reed stops of a pipe organ, and more especially the vox humana stop.The sound of the regal was...

. Because the resonator is partially stopped/closed by the Reed, odd-numbered partials/harmonics are dominant (in the hollow tones of Krumhorn and Clarinet stops, for example). If the resonator pipe expands outward to conical, the geometry allows the production of both even- and odd-numbered partials, resulting in the fuller tones of Trumpet and Oboe stops.

Diaphone pipes

The diaphone is a unique and uncommon organ pipe. Invented by Robert Hope-Jones
Robert Hope-Jones
Robert Hope-Jones , is considered to be the inventor of the theatre organ in the early 20th century...

 around 1900, it has characteristics of both flue pipes and reed pipes. The pipe speaks through a resonator, much like a reed pipe, but a spring-loaded pallet instigates the vibration instead of a reed. Possessing a powerful bass groundtone, the pipe is generally made of wood and can be voiced at various wind pressures. The diaphone is usually found at 16′ and 32′ pitches, however there are a few examples of 8′ diaphones. There are two 32' Diaphones in Philadelphia's Wanamaker Organ
Wanamaker Organ
The Wanamaker Grand Court Organ, in Philadelphia, Pennsylvania, is the largest operational pipe organ in the world, located within a spacious 7-story court at Macy's Center City . The largest organ by some measures is the Boardwalk Hall Auditorium Organ...

, and a full-length 64′ Diaphone-Dulzian is installed in the Boardwalk Hall Auditorium Organ in Atlantic City.

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. Wurlitzer
Wurlitzer
The Rudolph Wurlitzer Company, usually referred to simply as Wurlitzer, was an American company that produced stringed instruments, woodwinds, brass instruments, theatre organs, band organs, orchestrions, electronic organs, electric pianos and jukeboxes....

 built a version of the diaphonic horn for their theater organs at 32′ and 16′ pitches with huge wooden resonators as extensions of its Diaphonic diapason, and at 16′ with metal resonators as an extension of its smaller-scale Open diapason. The Austin Organ Company
Austin Organs, Inc.
Austin Organs, Inc. is a manufacturer of pipe organs based in Hartford, Connecticut. The company is one of the oldest continuously-operating organ manufacturers in the United States...

 also developed a metal diaphone at 16′ pitch known as a Magnaton. Due to its penetrating tone, the diaphone has also been used in foghorn
Foghorn
A foghorn or fog signal or fog bell is a device that uses sound to warn vehicles of hazards or boats of the presence of other vehicles in foggy conditions. The term is most often used in relation to marine transport...

s and fire signals.
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