Organ stop
An organ stop is a component of a 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 admits pressurized air (known as wind) to a set of organ pipe
Organ pipe
An organ pipe is a sound-producing element of the pipe organ that resonates at a specific pitch when pressurized air is driven through it. Each pipe is tuned to a specific note of the musical scale...

s. Its name comes from the fact that stops can be used selectively by the organist; some can be "on" (admitting the passage of air to certain pipes), while others can be "off" (stopping the passage of air to certain pipes).

The term can also refer to the control that operates this mechanism, commonly called a stop tab, stop knob, or drawknob.

The term is also sometimes used as a synonym for register, referring to rank(s) of pipes controlled by a single stop. Registration
Registration (organ)
Registration is the technique of choosing and combining the stops of a pipe organ in order to produce a particular sound. Registration can also refer to a particular combination of stops...

is the art of combining stops.


Organ pipes are physically organized within the organ according to note and 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...

, into sets. A set of pipes producing the same timbre for each note is called a rank, while each key on a pipe organ controls a note which may be sounded by different ranks of pipes, alone or in combination. The use of stops enables the organist to selectively turn off ("stop") certain ranks in order to produce different combinations of sounds, as opposed to hearing all sounds simultaneously. While nowadays one speaks of "drawing" a stop to select a particular rank, the earliest organs were constructed as blockwerk with all ranks 'on' by default.

The mechanism used to operate the stops varies widely, but the principle is the same: the stop control at the console allows the organist to select which ranks of pipes will sound when a key is pressed. When the organist desires a rank to sound, he or she operates the corresponding control at the console, allowing wind to flow to the pipes. Likewise, the organist can deny wind to the pipes by operating the same control in the opposite direction. Common stop controls include stop knobs, which move in and out of the console, and stop tabs, which toggle back and forth in position.

Some organs, particularly smaller historical organs from England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 or Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, feature divided registers, in which there are two stop knobs for certain ranks. One stop knob will control the upper portion of the keyboard, and the other will control the lower portion of the keyboard. This arrangement allows the upper portion of the keyboard to sound a different registration than the lower portion, which lends a greater versatility to smaller organs, especially those with only one manual
Manual (music)
A manual is a keyboard designed to be played with the hands on a pipe organ, harpsichord, clavichord, electronic organ, or synthesizer. The term "manual" is used with regard to any hand keyboard on these instruments to distinguish it from the pedalboard, which is a keyboard that the organist plays...


Methods of stop actuation

Over the course of the history of the pipe organ, there have been several different designs by which stops are actuated. In the longest-standing design, known as the slider chest, there is a strip of material (typically wood) called a slider which fits underneath a given rank of pipes. The slider has small holes drilled in it, one for each pipe in the rank. When the stop is set such that pipes are inactive, the holes are misaligned with the pipes, preventing the air from flowing up into the pipes above. When the stop is set such that the pipes are active, the slider moves over, aligning the holes with the pipes, allowing air to reach them. Because the slider chest was developed before the advent of electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

, it is inherently mechanical in nature. However, it has been adapted to operate with electricity as an actuating component.

Other common designs include the spring chest, the cone valve chest, and the Pitman chest.

Unification and Extension

The term unification refers to the practice of expanding the tonal resources of an organ without adding extra pipes. Borrowing or duplexing refers to one rank being made available from more than one stop knob. This allows the rank to be played at a different pitch or on a different manual. Extension refers to the addition of extra pipes to the high and/or low ends of a rank in order to allow that rank to be borrowed at a higher and/or lower pitch.

Borrowing between manuals occurs in English organs from about 1700, but extension of pipe ranks for the purpose of borrowing at different pitches is a relatively recent development.

Extension and unification were heavily used in theatre organ
Theatre organ
A theatre organ is a pipe organ originally designed specifically for imitation of an orchestra. New designs have tended to be around some of the sounds and blends unique to the instrument itself....

s to produce the maximum number of voices from a minimal number of pipes. Traditionally, less use has been made of extension in church organs and those designed for classical music, with authorities tending to regard borrowing in general and extension in particular as things to be avoided if possible, except in a few cases where space for pipes is limited, making extension and/or unification necessary.

Pitch and length

The pitch produced by an organ pipe is a function of its length. Longer pipes produce lower pitched notes, while shorter pipes are higher in tone. An organ stop utilizes a set (rank) of pipes of graduated lengths to produce the range of notes needed. Stops having ranks of pipes that are sized and tuned to sound the pitch normally associated with the keys (i.e. the pitch of same keys on a piano
The piano is a musical instrument played by means of a keyboard. It is one of the most popular instruments in the world. Widely used in classical and jazz music for solo performances, ensemble use, chamber music and accompaniment, the piano is also very popular as an aid to composing and rehearsal...

) are called "unison stops". Other stops use pipework which is longer or shorter than that of unison ranks to speak at a fixed interval above or below unison pitch. ("octave pitch" or "mutation pitch")

The pitch of a rank of pipes is denoted by a number on the stop knob. A stop which speaks at unison pitch, or "native pitch" is known as an 8' stop. This nomenclature refers to the approximate length of the longest pipe in a rank of open pipes
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...

. In a rank of stopped pipes
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...

, the lowest pipe is about 4 feet in length, but because it sounds a unison pitch, it is also known as an 8' stop.

The octave sounded by a given pipe is inversely proportional to its length ("1/2 the length = double the pitch"), meaning that a 4' stop speaks exactly one octave higher than an 8' stop. Likewise, a 2' stop speaks exactly one octave higher than a 4' stop. Conversely, a 16' stop speaks exactly one octave below an 8' stop; and a 32′ stop speaks exactly one octave below a 16' stop. Octave pitch lengths used in actual organs include 64', 32', 16', 8', 4', 2', 1', and 1/2'.



Ranks that do not speak at the unison or some octave of the unison pitch are called mutation stops (or, sometimes "aliquots"). They are rarely used on their own; rather, they are combined with unison stops to create different tone colors. A typical and distinctive sound of the organ is the cornet, composed of a flute and ranks making up its first four overtones, sounding 8', 4', 2 2/3', 2', and 1 3/5'.

The sounding length of a mutation stop gives the answer as to what pitch the rank sounds. For example, a stop labeled 2 2/3' (or one third of 8') sounds at three times the frequency, that is, the interval
Interval (music)
In music theory, an interval is a combination of two notes, or the ratio between their frequencies. Two-note combinations are also called dyads...

 of a twelfth above unison pitch. The third harmonic (twelfth, quint or nazard) is the most common pitch, followed by the fifth (17th or tierce) and sixth (larigot) but there are much rarer examples from higher in the series, such as the "septième" and "none".

Mutations usually sound at pitches in the harmonic series
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...

 of the fundamental and, except where they are derived from unit ranks, are always tuned pure
Just intonation
In music, just intonation is any musical tuning in which the frequencies of notes are related by ratios of small whole numbers. Any interval tuned in this way is called a just interval. The two notes in any just interval are members of the same harmonic series...

. In some organs, lower pitches are used to create difference tones
Combination tone
A combination tone, also called a sum tone or a difference tone , can be any of at least three similar psychoacoustic phenomena. When two tones are played simultaneously, a listener can sometimes perceive an additional tone whose frequency is a sum or difference of the two frequencies...

 e.g. Quintbass 10 2/3'. Such 'helper ranks" that sound at the fifth just above or fourth below the fundamental (e.g. Bourdon 16'), can create the impression of a stop an octave lower than the fundamental (i.e. Bourdon 32'), saving the space and money otherwise needed for larger bass pipes.


Certain stops called mixtures
Mixture (music)
A mixture is an organ stop, usually of principal tone quality, that contains multiple ranks of pipes. It is designed to be drawn with a combination of stops that forms a complete chorus . The mixture sounds the upper harmonics of each note of the keyboard...

contain multiple ranks of pipes sounding at consecutive octaves and fifths (and in some cases, thirds) above unison pitch. The number of ranks in a mixture is denoted by a Roman numeral on the stop knob; for example, a stop labeled "Mixture V" would contain five pipes for every note. So for every key pressed, five different pipes sound (all controlled by the same stop).


Pipe ranks have particular names, which depend on a number of factors ranging from the physical and tone attributes of the pipes in that rank, to the country and era in which the organ was manufactured, to the pipes' physical location within the organ. Each stop knob is labeled with the name of the rank it controls. In general, that label gives the organist two vital pieces of information about the rank of pipes in question:
  • Which octave of pitches the rank is natively tuned to
  • Which tone quality the rank possesses (for example trumpet, flute, etc.)

This is an example of a typical pipe organ stoplist, showing both common stop names and conventional formatting (flue pipe
Flue pipe
A flue pipe is an organ pipe that produces sound through the vibration of air molecules, in the same manner as a recorder or a whistle. Air under pressure is driven down a flue and against a sharp lip called a Labium, causing the column of air in the pipe to resonate at a frequency determined by...

s listed in black, reed pipe
Reed pipe
A reed pipe is an organ pipe that is sounded by a vibrating brass strip known as a reed. Air under pressure is directed towards the reed, which vibrates at a specific pitch. This is in contrast to flue pipes, which contain no moving parts and produce sound solely through the vibration of air...

s listed in red):

Classifications of stops

All audio examples are provided courtesy of the Encyclopedia of Organ Stops, by Edward Stauff.

Stop names are indicative of the tone made by the rank(s) of pipes they control. Organ pipes fall into five broad categories:
  • Principal (or Diapason)
    Listen to example
    Principal stops are non-imitative; that is, their sound does not attempt to imitate that of a particular instrument. The Principal sound is the one sound which is unique to the pipe organ; it is the sound which comes to mind in the context of traditional church music (such as hymns). While spellings and names vary by language and era, here are some common examples:
    • Principal (also Diapason, Open Diapason, or Montre)
    • Octave
    • Super Octave (also Doublette or Fifteenth)
    • Twelfth (sometimes in the Flute category)
    • Mixture (also Fourniture, Plein Jeu, Cymbal, or Sharp followed by a Roman Numeral; example: Mixture III, or Fourniture IV-VI)
  • Flute
    Listen to example
    Flute stops attempt to imitate (to one degree or another) the sound of flute-class woodwind instruments, such as the transverse flute
    Transverse flute
    A transverse flute or side-blown flute is a flute which is held horizontally when played. The player blows "across" the embouchure hole, in a direction perpendicular to the flute's body length....

     and piccolo
    The piccolo is a half-size flute, and a member of the woodwind family of musical instruments. The piccolo has the same fingerings as its larger sibling, the standard transverse flute, but the sound it produces is an octave higher than written...

    . Common examples:
    • Flute (or Flöte)
    • Traverse Flute (or Transverse Flute)
    • Stopped Diapason (or Stopped Flute) — despite its name, the Stopped Diapason is a flute-class stop
    • Bourdon
    • Gedeckt (or Gedackt)
    • Piccolo
    • Rohrflöte (or Chimney Flute)
    • Cor de Nuit (or Night Horn / Nachthorn)
    • Flautino
    • Spill Flote
    • Spitz Flote
    • Flach Flote
    • Twelfth (sometimes in the Principal category)
    • Sifflet (or Sifflöte)
    • Octavin (or Flûte Octaviante)
    • Nazard
    • Tierce
    • Flûte d'Amour
    • Melodia
    • Flûte Harmonique (or Harmonic Flute)
    • Sub Bass (or Subbass or Sousbasse)
    • Major Bass
  • String
    Listen to example
    String stops attempt to imitate (to one degree or another) the sound of stringed instruments, such as the violin
    The violin is a string instrument, usually with four strings tuned in perfect fifths. It is the smallest, highest-pitched member of the violin family of string instruments, which includes the viola and cello....

     and cello
    The cello is a bowed string instrument with four strings tuned in perfect fifths. It is a member of the violin family of musical instruments, which also includes the violin, viola, and double bass. Old forms of the instrument in the Baroque era are baryton and viol .A person who plays a cello is...

    . Common examples:
    • Viola
    • Gamba (or Viola da Gamba)
    • Vox Celeste (or Voix Céleste)
    • Violina
    • Dulciana
    • Cello
  • Reed
    Listen to example
    Reed stops attempt to imitate (to one degree or another) the sound of brass instrument
    Brass instrument
    A brass instrument is a musical instrument whose sound is produced by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips...

    s, such as the trumpet
    The trumpet is the musical instrument with the highest register in the brass family. Trumpets are among the oldest musical instruments, dating back to at least 1500 BCE. They are played by blowing air through closed lips, producing a "buzzing" sound which starts a standing wave vibration in the air...

     and tuba
    The tuba is the largest and lowest-pitched brass instrument. Sound is produced by vibrating or "buzzing" the lips into a large cupped mouthpiece. It is one of the most recent additions to the modern symphony orchestra, first appearing in the mid-19th century, when it largely replaced the...

    , and reed instruments such as the 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...

    , oboe
    The oboe is a double reed musical instrument of the woodwind family. In English, prior to 1770, the instrument was called "hautbois" , "hoboy", or "French hoboy". The spelling "oboe" was adopted into English ca...

    , and human voice
    Human voice
    The human voice consists of sound made by a human being using the vocal folds for talking, singing, laughing, crying, screaming, etc. Its frequency ranges from about 60 to 7000 Hz. The human voice is specifically that part of human sound production in which the vocal folds are the primary...

    . Common examples:
    • Trumpet (or Trompete, Trompette, Trompette en chamade or fanfare trumpet)
    • Trombone (or Posaune)
    • Tuba
    • Oboe (or Hautbois)
    • Cromorne (or Krummhorn)
    • Vox Humana (or Voix Humaine)
    • Bombarde
    • Ophicleide
    • Posaune
    • Clarinet
    • Cornopean
  • Hybrid
    Listen to example of String + Principal
    Hybrid stops contain one rank of pipes which attempts to combine the tones of two other classifications of stops, such as Principal + String, String + Flute, or Principal + Flute. Common examples:
    • Geigen (or Geigen Diapason", Geigen Principal, or Violin Diapason)
    • Salicional
      combination of String + Principal
    • Erzähler
    • Gemshorn
      combination of Flute + Principal

Notable organ stops

  • The loudest organ stop in the world is the Grand Ophicleide located in the Right Pedal division of the Boardwalk Hall Auditorium Organ. It stands on 100″ wind pressure. Rumor has it that the former organ curator always warned the stagehands when the Grand Ophicleide was going to be used, because of the sheer volume.
  • The mixture stop with the largest numbers of pipes, called Ple, can be found in Santanyí (Majorca), Spain. It has twenty-two ranks in the left hands and twenty-five in the right.
  • There are only two true and complete, non digital, acoustic and down to the sub-sub-contra-C, 64' stops in the world. The Contra-Trombone 64′ in the Sydney Town Hall Grand Organ
    Sydney Town Hall Grand Organ
    The Sydney Town Hall Grand Organ is a large pipe organ built by English firm William Hill & Son in 1890. It is located in the Centennial Hall of Sydney Town Hall in Sydney, New South Wales, Australia....

     (click here for a sound sample), and the Diaphone-Dulzian 64′ in the Boardwalk Hall Auditorium Organ (click here for a sound sample). More organs have a 64′ stop in their stoplist, but nearly all of these are either acoustic imitations-(32′ combined with a 21 1/3 extension creating a 64′ impression)- or else a sound sample of a higher-pitched stop electronically altered to sound 1+ octaves lower. The Boardwalk Hall Auditorium Organ is capable of creating a resultant 128' stop by combining its 64' and 42 2/3' stops.
    • These sound samples start with the 16' CCC then goes down 2 octaves to the 64' CCCCC.
  • Some other organs also have a part of the lowest 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"...

    , usually the top 3 or 4 pipes.
  • There are Percussion (tuned and untuned) stops and it is unknown if they are in the Flute, Principal, String, Reed, or Hybrid category.

Further reading

  • Stevens Irwin Dictionary of Pipe Organ Stops
  • George Ashdown Audsley Organ Stops and Their Artistic Registration

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.