Flue Pipe
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A flue pipe (also referred to as a ''labial'' pipe) is an
organ pipe An organ pipe is a sound-producing element of the pipe organ that resonates 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. A set of ...
that produces sound through the vibration of air molecules, in the same manner as a
recorder Recorder or The Recorder may refer to: Newspapers * ''Indianapolis Recorder'', a weekly newspaper * ''The Recorder'' (Massachusetts newspaper), a daily newspaper published in Greenfield, Massachusetts, US * ''The Recorder'' (Port Pirie), a news ...
or a
whistle A whistle is an instrument which produces sound from a stream of gas, most commonly air. It may be mouth-operated, or powered by air pressure, steam, or other means. Whistles vary in size from a small slide whistle or nose flute type to a larg ...
. Air under pressure (called ''wind'') is driven through a
flue A flue is a duct, pipe, or opening in a chimney for conveying exhaust gases from a fireplace, furnace, water heater, boiler, or generator to the outdoors. Historically the term flue meant the chimney itself. In the United States, they are ...
and against a sharp lip called a ''labium'', causing the column of air in the pipe to resonate at a frequency determined by the pipe length (see
wind instrument A wind instrument is a musical instrument that contains some type of resonator (usually a tube) in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece set at or near the end of the resonator. The pitc ...
). Thus, there are no moving parts in a flue pipe. This is in contrast to
reed pipe A reed pipe (also referred to as a ''lingual'' pipe) is an organ pipe that is sounded by a vibrating brass strip known as a ''reed''. Air under pressure (referred to as ''wind'') is directed towards the reed, which vibrates at a specific pitc ...
s, whose sound is driven by beating reeds, as in a
clarinet The clarinet is a musical instrument in the woodwind family. The instrument has a nearly cylindrical bore and a flared bell, and uses a single reed to produce sound. Clarinets comprise a family of instruments of differing sizes and pitches ...
. Flue pipes are common components of
pipe organ The pipe organ is a musical instrument that produces sound by driving pressurized air (called ''wind'') through the organ pipes selected from a keyboard. Because each pipe produces a single pitch, the pipes are provided in sets called ''ranks ...
s.


Stop

Flue pipes include all
stop Stop may refer to: Places * Stop, Kentucky, an unincorporated community in the United States * Stop (Rogatica), a village in Rogatica, Republika Srpska, Bosnia and Herzegovina Facilities * Bus stop * Truck stop, a type of rest stop for truck d ...
s of the "Principal", "Flute", and "String" classes, and some stops from the "Hybrid" class.


Construction

Flue pipes may be metallic or wooden. Metal pipes are usually circular in cross section; wooden pipes are usually square or rectangular, though triangular and round wooden pipes do exist. A flue pipe has two major parts, a foot and a resonator. The ''foot'' is the bottom portion of the pipe, usually conical. At its base is the ''toe hole'', through which wind enters it. The length of the foot does not affect the pipe's pitch, so organ builders vary the foot lengths of their flue pipes depending on other factors, including the desired shape of the pipes in the façade, the height of the rackboard in which the pipes are seated, and the weight of the completed pipe. The ''resonator'' supports the oscillations of air generated at the ''mouth'' of the pipe, a horizontal opening at the juncture of the resonator with the foot. The voicing, the length of the resonator, and the resonator's volume all determine the fundamental pitch of the flue pipe. The conical taper of the pipe determines the overblown pitch. If the pipe is metal, a ''tuning sleeve'' or ''tuning collar'' may be fixed at the top of the resonator and raised or lowered to vary its length, thereby adjusting the pitch produced. Between the foot and the resonator, the side of the pipe containing the mouth is flat. A plate of metal or wood called a ''languid'', fixed horizontally here, blocks the airway, except for a small slot called the ''windway'' alongside the mouth. This allows air to flow as a sheet of wind directed towards the pipe's mouth. Flat pieces of metal or wood called ''ears'' may be attached to the sides of the mouth for tuning purposes, and a horizontal dowel called a ''roller'' or ''beard'' may be affixed at the pipe to ensure prompt pipe speech.


Actuation

When wind is driven into the foot of the pipe, a sheet of wind is focused by the windway across the mouth to strike just above the edge of the upper lip. This creates a
Bernoulli effect In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy. The principle is named after the Swiss mathemat ...
, or "siphon effect", causing a low
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
area to be created just below the mouth. When this low pressure area reaches a critical stage, it pulls the airstream past the edge of the mouth, filling the vacuum. This alternately pressurizes the inside and outside of the opening, pressurizing and rarefying the air in the pipe's resonator. The column of air in the resonator thus vibrates at a frequency determined by the pipe's dimensions. Mainstone, John (1999), "The physics of the organ," in Thistlethwaite, Nicholas and Webber, Geoffrey (eds.), '' The Cambridge Companion to the Organ'' (Cambridge: Cambridge University Press), p. 31–41. See
Wind Instrument A wind instrument is a musical instrument that contains some type of resonator (usually a tube) in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece set at or near the end of the resonator. The pitc ...
.


Tonal groups

Flue pipes generally belong to one of three tonal families: ''flutes'', ''diapasons'' (or ''principals''), and ''strings''. The basic "foundation" (from the French term ) sound of an organ is composed of varying combinations of these three tonal groups, depending upon the particular organ and the
repertory A repertory theatre is a theatre in which a resident company presents works from a specified repertoire, usually in alternation or rotation. United Kingdom Annie Horniman founded the first modern repertory theatre in Manchester after withdrawing ...
being played. The end of the pipe opposite the mouth may be either open or closed (also known as Gedackt or ''stopped''). A closed pipe sounds an octave lower than an open pipe of the same length. Also, an open pipe produces a tone in which both the even-numbered and the odd-numbered partials are present, while a stopped pipe 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.


Flutes

In the system of
organ flue pipe scaling Scaling is the ratio of an organ pipe's diameter to its length. The scaling of a pipe is a major influence on its timbre. Reed pipes are scaled according to different formulas than for flue pipes. In general, the larger the diameter of a given pi ...
, "flutes" are generally the widest flue pipes and produce the tone with the most
fundamental Fundamental may refer to: * Foundation of reality * Fundamental frequency, as in music or phonetics, often referred to as simply a "fundamental" * Fundamentalism, the belief in, and usually the strict adherence to, the simple or "fundamental" idea ...
and the least
harmonics A harmonic is a wave with a frequency that is a positive integer multiple of the '' fundamental frequency'', the frequency of the original periodic signal, such as a sinusoidal wave. The original signal is also called the ''1st harmonic'', ...
among flue pipes. They are so named because they sound like a
flute The flute is a family of classical music instrument in the woodwind group. Like all woodwinds, flutes are aerophones, meaning they make sound by vibrating a column of air. However, unlike woodwind instruments with reeds, a flute is a reedless ...
instrument; though most flute stops are not intended to imitate a specific kind of flute, such as the modern orchestral instrument, they produce similar sounds. A stopped flute, such as the ' (
German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
for "covered"), produces a more muffled sound, while an open flute, such as the ' (German for "forest flute"), produces a rounder, open sound. The ' ( French for "harmonic flute"), whose use the great 19th-century French organ builder Aristide Cavaillé-Coll advocated, is a metal flute pipe of double length with a hole punched in the center, which causes the pipe to speak at its first partial with a very round, intense sound. Cavaillé-Coll used the names ' and ' for the 4-foot and 2-foot harmonic flutes, respectively. The ' (German for "pipe flute", or more commonly "chimney flute" in English) is a stopped flute rank with a small pipe or chimney built into the cap.


Diapasons

''Diapasons'' or ''principals'' represent the characteristic sound of the pipe organ. They are not intended to imitate any other instrument or sound. They are medium-scaled and are often prominently featured in the façades of pipe organs, often painted and decorated. Diapasons appear throughout the entire range of the instrument, from 32′ pitch to 1′ pitch (not including
mixtures In chemistry, a mixture is a material made up of two or more different chemical substances which are not chemically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the ...
), a range of nine octaves. A stop of diapason type may or may not actually be labelled "Diapason". The "Diapason" label is most commonly used in English and American-style organs, whereas the same type of stop is known as a "Prinzipal" or "Principal" on German-style organs, and for French organs they would typically be called "Montre" (literally on "Display" - i.e. the pipes at the front of the organ case) or "Prestant" ("standing in front" - Latin ). Furthermore, diapasons at pitches higher than 8′ pitch (pronounced 8 foot, referring to the length of the resonator part of the longest pipe of the stop) are often labelled with other names. For example, on English-style organs, the stops called Principal and Fifteenth sound one octave and two octave pitches respectively above the 8′ Diapason; on German-style organs, the name Octav is used to indicate the stop an octave above the 8′ Prinzipal, and similarly for French instruments, the names Octave and Doublette for 4′ and 2′ pitches respectively are commonly used. In Italian organs, the 8′ and sometime the 16′ pitches are called "Principale" and form the foundation of the entire organ. One characteristic of the classic Italian organ (starting from the 16th century on) is the separated "Ripieno". The "Ripieno" includes many Diapason stops, all separate, in contrast to the German and French style "Fourniture" and "Mixtur". The 4′ pitch is called "Ottava" and all the others are named after the harmonic they produce. They can go up to the "Quadragesima Terza" (43rd), a pipe of ′ pitch.


Strings

''String pipes'' are the smallest-scaled (narrowest) flue pipes. They produce a bright sound that is low in fundamentals and rich in upper partials. String stops are generally named after bowed
string instruments String instruments, stringed instruments, or chordophones are musical instruments that produce sound from vibrating strings when a performer plays or sounds the strings in some manner. Musicians play some string instruments by plucking the Str ...
such as the Violoncelle, the
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, the Geigen (from the German , for
violin The violin, sometimes known as a ''fiddle'', is a wooden chordophone (string instrument) in the violin family. Most violins have a hollow wooden body. It is the smallest and thus highest-pitched instrument (soprano) in the family in regular ...
), and the
Viol The viol (), viola da gamba (), or informally gamba, is any one of a family of bowed, fretted, and stringed instruments with hollow wooden bodies and pegboxes where the tension on the strings can be increased or decreased to adjust the pitc ...
. One of the most famous organs with a String Division is the
Wanamaker Organ The Wanamaker Grand Court Organ, located in Philadelphia, Pennsylvania (United States of America) is the largest fully-functioning pipe organ in the world, based on the number of playing pipes, the number of ranks and its weight. (The Boardwalk H ...
.


Undulating stops

Often, an organ will feature two similarly-voiced stops, one tuned slightly sharp or flat of the other. When these stops are played together, a unique undulating effect results due to alternating constructive and destructive interference (
beat frequency In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, ''perceived'' as a periodic variation in volume whose rate is the difference of the two frequencies. With tuning instruments that can produce ...
). Examples include the ''Voix céleste'' (French for ''celestial voice''), typically tuned slightly sharp, and the ''Unda maris'' (
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
for ''sea waves''), typically tuned slightly flat. String stops are most commonly used as undulating stops, though some builders have made undulating flute stops (notably Ernest M. Skinner's Flute celeste). Rare outside Italy is an undulating diapason, as in the Italian "Voce Umana" (not to be confused with the Vox Humana, which is a soft reed stop with a short resonator).


Labial reeds

Some flue pipes are designed to produce the sounds of reed pipes or to imitate the sounds of orchestral instruments which are approximated by reed pipes. The sound is generally more mellow and sweet than that of a true reed pipe. Examples include the Saxophone, the Muted horn, the Clarinet flute, and the Echo oboe.


Tonal characteristics

The diameter of a flue pipe directly affects its tone. When comparing pipes of otherwise identical shape and size, a wide pipe will tend to produce a flute tone, a medium pipe a diapason tone, and a narrow pipe a string tone. These relationships are referred to as the scale of the pipe: i.e., wide-scaled, normal-scaled, or narrow-scaled. As a pipe's scale increases, more fundamental will be present, and fewer partials will be present in the tone. Thus, the tone becomes richer and fuller as the pipe's diameter widens from string scale to principal scale to flute scale. The material out of which the pipe is constructed also has much to do with the pipe's final sound. While recent scientific studies have shown that the nature of the metal used in making the pipe has little or no effect on the final sound, organ builders agree that a tin/lead alloy, for example, creates a very different tone than does zinc or copper metals or spotted or frosted alloys.


References


External links


Encyclopedia of Organ Stops
{{DEFAULTSORT:Flue Pipe Organ stops Pipe organ components