The pipe organ is a musical instrument that makes sound by sending air (called wind) through pipes chosen by pressing keys on a keyboard. Each pipe creates one note and one pitch, so pipes are grouped into sets called ranks. All pipes in a rank have the same sound quality, loudness, and design, but they produce different pitches. Most pipe organs have many ranks with different pitches, sounds, and volumes. Players can use these ranks alone or together by using controls called stops.

A pipe organ has one or more keyboards (called manuals) played with the hands, and most have a pedalboard played with the feet. Each keyboard controls its own group of stops. The keyboards, pedalboard, and stops are found in the organ's console. The pipe organ has a steady air supply that keeps notes playing as long as the keys are pressed, unlike the piano or harpsichord, which stop making sound once the keys are released. Small portable pipe organs may have only a few pipes and one keyboard, while the largest can have over 33,000 pipes and seven keyboards. A list of famous and large pipe organs can be found at "List of pipe organs." A ranking of the largest pipe organs, based on the number of ranks and equipment controlled from one console, is published in "The Organ" magazine and "Vox Humana" journal.

The pipe organ's history began with the hydraulis, an instrument from Ancient Greece in the 3rd century BC, which used water pressure to create air. By the 6th or 7th century AD, bellows were used to supply air to organs in the Byzantine Empire. In 757, the Byzantine emperor Constantine V sent a pipe organ with large pipes as a gift to Pepin the Short, King of the Franks. Pepin's son, Charlemagne, asked for a similar organ for his chapel in Aachen in 812, which helped spread the pipe organ in Western European church music. In England, the first detailed record of an organ was from the 10th century in Winchester Cathedral. It had 400 pipes, needed two people to play it, and 70 people to blow air into it. Its sound could be heard across the city. By the 12th century, the organ became more complex and could create different sounds. By the 17th century, most of the sounds found on modern pipe organs had been developed. At that time, the pipe organ was the most complex man-made device until the telephone exchange was invented in the late 19th century.

Pipe organs are found in churches, synagogues, concert halls, schools, homes, and public buildings. They are used to play classical, sacred, secular, and popular music. In the early 20th century, pipe organs were placed in theaters to accompany silent films, in public halls for orchestral music, and in the homes of wealthy people. In the 21st century, there has been a renewed interest in installing pipe organs in concert halls. A large collection of music written for pipe organs has been created over 500 years.

History and development

The organ is one of the oldest musical instruments still used in European classical music. It is often said to have originated in ancient Greece. The earliest versions of the organ were built in Greece around 300 BC. The word "organ" comes from the Greek word órganon, which means a tool or instrument. This word was later used in Latin as organum, describing an instrument similar to a portable organ used in Roman games.

The Greek engineer Ctesibius of Alexandria is credited with inventing the first organ in the 3rd century BC. He created an instrument called the hydraulis, which used water pressure to send air through pipes. This instrument was played in Roman arenas. Later, around the 2nd century AD, the water system of the hydraulis was replaced with an inflated leather bag. By the 6th or 7th century AD, true bellows began to appear in the Eastern Roman Empire. In 1931, archaeologists found parts of a hydraulis from 228 AD in Aquincum, a Roman town near modern Budapest. A modern copy of this instrument produces pleasant sounds.

In the 9th century, a Persian writer named Ibn Khurradadhbih mentioned the urghun (organ) as a common instrument in the Eastern Roman (Byzantine) Empire. It was often played in Constantinople’s Hippodrome. A Syrian visitor described a pipe organ operated by two servants using bellows like those used by blacksmiths during a royal Christmas dinner in 911. In 757, the Byzantine emperor Constantine V sent a Western European pipe organ with large metal pipes as a gift to Pepin the Short, king of the Franks. Pepin’s son, Charlemagne, later requested a similar organ for his chapel in Aachen, starting its use in church music.

From 800 to the 1400s, organs became more advanced. Early versions included the portative and positive organs, which were small and portable. The portative organ was played with one hand on the keyboard and the other controlling the bellows. It was used for both religious and secular music. The positive organ was larger but still portable. By the 13th century, portative organs in medieval manuscripts showed keyboards with balanced keys, like those in the Cantigas de Santa Maria.

It is unclear exactly when large organs were first installed in Europe. A description by Wulfstan of Winchester from before the 13th century mentions an organ with bronze pipes. This suggests the organ was large and permanent. The first permanently installed organ was in 1361 in Halberstadt, Germany. This organ had a special keyboard layout and required ten men to operate its bellows. The organ was called "the king of instruments" by Guillaume de Machaut.

By the late 13th and 14th centuries, organs were used in major cathedrals like Notre Dame. Records show organists were hired to play during religious events. The organ was used for preludes, postludes, and interludes, not just for choir music. Earlier medieval organs had keyboards and casings but no pipes. Until the mid-15th century, organs lacked stop controls, which allowed individual pipe sets to be played. These controls evolved into modern stop actions.

During the Renaissance and Baroque periods, organs developed more varied sounds. Builders created stops that mimicked instruments like the krummhorn and viola da gamba. Organ makers like Arp Schnitger and Gottfried Silbermann created instruments with precise key actions and rich tones. In the Netherlands, organs became large with multiple sections and cornets. In northern Germany, organs had more divisions and independent pedal sections. These styles were later called Werkprinzip by 20th-century scholars.

In France, Italy, Spain, and Portugal, organ styles also evolved, reflecting local traditions and artistic influences.

Construction

A pipe organ has one or more sets of pipes, a wind system, and one or more keyboards. The pipes make sound when pressurized air from the wind system passes through them. An action connects the keyboards to the pipes. Stops let the organist choose which sets of pipes play at a certain time. The organist uses the stops and keyboards from the console.

Organ pipes are made of wood or metal and make sound when air under pressure is directed through them. One pipe makes one musical note, so many pipes are needed to cover all the notes in a scale. Longer pipes make lower notes, while shorter pipes make higher notes. The sound quality and loudness of a pipe depend on how much air reaches it and how it is built and adjusted by the organ builder. Once a pipe is playing, its loudness cannot be changed easily.

Organ pipes are grouped into two types: flue pipes and reed pipes. Flue pipes make sound by air passing through a narrow opening, like a recorder. Reed pipes make sound using a vibrating reed, like a clarinet or saxophone.

Pipes are organized into ranks. A rank is a group of pipes that all have the same sound quality but different pitches (one for each key on the keyboard). Ranks are attached to a windchest, which holds the pipes. Stops control whether air reaches a rank. For a pipe to play, the stop for its rank must be turned on, and the key for its note must be pressed. Ranks are grouped into divisions, each usually played from its own keyboard and acting like a separate instrument.

An organ has two actions: the keys and the stops. The key action lets air into the pipes when a key is pressed. The stop action lets a rank of pipes play when a stop is turned on. Actions can be mechanical, pneumatic, or electrical, or a mix of these. The key action and stop action work separately, allowing different types of systems to be used together.

A mechanical key action uses rods and levers to connect the keys to the windchests. When the organist presses a key, a rod called a tracker pulls open a valve, letting air into the pipe.

In a mechanical stop action, each stop controls a valve for an entire rank of pipes. When the organist selects a stop, the valve allows air to reach the pipes. Early stop controls were draw stop knobs, which the organist pulled to turn them on. This led to the phrase "to pull out all the stops." Modern stop controls are switches or magnetic valves operated by tabs.

Tracker action has been used for a long time. Before a valve opens, wind pressure tightens the spring that holds the valve closed. Once the valve opens, the spring tension is the only force felt by the organist, creating a sudden lightness when the key is pressed.

A later type of action is the tubular-pneumatic action, which uses air pressure in metal tubes to control valves. This allowed for a lighter touch and more flexibility in where the console could be placed, up to about 50 feet away. This type was used in the late 1800s and early 1900s but is rarely used today.

A newer type is the electric action, which uses low-voltage electricity to control the keys and stops. Electricity can work indirectly by controlling air pressure valves (pneumatics) or directly using electromagnets. In direct electric actions, an electromagnet moves a disc to open a valve. Electric actions allow the console to be placed far from the rest of the organ and can be moved easily. Stops can be controlled by switches, tabs, or tilting panels.

Computers now allow the console and windchests to be connected using thin cables instead of many wires. These cables use complex communication methods, similar to how musical instruments like MIDI devices work.

The wind system includes parts that create, store, and deliver air to the pipes. Pipe organs use about 0.10 psi of air pressure, which is measured using a U-shaped tube filled with water. The difference in water levels in the tube shows the pressure. Some old organs used less pressure, while large modern organs may use up to 100 inches of water pressure.

Before electric blowers, someone called a calcant had to manually operate bellows to provide air. Later, bellows were powered by water, steam, or gasoline engines. By the 1860s, turbines connected to electric motors replaced bellows, letting organists practice regularly. Most modern and old organs now use electric blowers, though some can still be operated manually. Air is stored in regulators to keep pressure steady until the action allows it to flow into the pipes.

Each stop usually controls one rank of pipes, though some stops, like mixtures or undulating stops such as the Voix céleste, control multiple ranks. The name of a stop often describes its sound and purpose.

Repertoire

The development of organ music has grown along with the instrument itself, creating unique styles of music in different countries. Since organs are often found in churches and synagogues, much of the organ repertoire includes sacred music. This sacred music includes pieces that support singing (like choral anthems, hymns, and liturgical parts) and pieces that are played alone (such as chorale preludes and hymn versets used alternately). The secular (non-religious) organ repertoire includes preludes, fugues, sonatas, organ symphonies, suites, and copies of orchestral music.

Many countries in the Western tradition have contributed to the organ repertoire, but France and Germany have created especially large amounts of organ music. The Netherlands, England, and the United States also have extensive organ music collections.

Important examples of organ music include:
– Johann Sebastian Bach’s works (by Haussmann, c. 1748)
– César Franck (by Rongier, 1888) at the organ in Saint Clotilde, Paris
– Camille Saint-Saëns (by Nadar), who included a famous organ part in his Symphony No. 3, sometimes called the Organ Symphony
– Olivier Messiaen (1986), who created new and unique styles of organ music

Before the Baroque era, keyboard music was often written to be played on any keyboard instrument, not just the organ. Because of this, much of the organ’s music from the Renaissance period is the same as that of the harpsichord. Earlier keyboard music is found in manuscripts that include compositions from different regions. The oldest of these is the Robertsbridge Codex, from about 1360. The Buxheimer Orgelbuch, from around 1470, includes music by the English composer John Dunstaple. The earliest Italian organ music is in the Faenza Codex, from 1420.

During the Renaissance, Dutch composers like Jan Pieterszoon Sweelinck wrote fantasias and psalm settings. Sweelinck created complex keyboard patterns that influenced later composers. The Italian composer Claudio Merulo wrote in the styles of the toccata, canzona, and ricercar. In Spain, Antonio de Cabezón began a long period of Spanish organ music that ended with Juan Cabanilles.

In the early Baroque period, German organ music was highly interwoven. Sacred music was based on chorales, with composers like Samuel Scheidt and Heinrich Scheidemann writing chorale preludes, fantasias, and motets. Near the end of the Baroque era, chorale preludes and partitas combined to form the chorale partita, developed by Georg Böhm, Johann Pachelbel, and Dieterich Buxtehude. The main free-form piece of this time was the praeludium, as seen in the works of Matthias Weckmann, Nicolaus Bruhns, Böhm, and Buxtehude. Johann Sebastian Bach’s music combined all national styles in his large preludes, fugues, and chorale-based works. George Frideric Handel composed the first organ concertos.

In France, organ music developed during the Baroque era through composers like Jean Titelouze, François Couperin, and Nicolas de Grigny. French organs of the 17th and early 18th centuries were standardized, leading to a set of common ways to play them. Music by French and Italian composers like Girolamo Frescobaldi was written for use during the Mass. Very little secular organ music was written in France and Italy during the Baroque period; most was for religious use. In England, composers like John Blow and John Stanley wrote multi-part works for religious use called voluntaries until the 19th century.

Organ music was rarely written during the Classical era because composers preferred the piano, which could create dynamic changes. In Germany, Felix Mendelssohn’s six sonatas (published in 1845) started a renewed interest in organ music. French composers like César Franck, Alexandre Guilmant, and Charles-Marie Widor, inspired by new Cavaillé-Coll organs, expanded organ music into the symphonic style. This development continued with Louis Vierne and Charles Tournemire. Widor and Vierne wrote large, multi-movement works called organ symphonies, such as Widor’s Symphony No. 6 and Vierne’s Symphony No. 3. Max Reger and Sigfrid Karg-Elert used the capabilities of large Romantic-era organs in their symphonic works.

In the 19th and 20th centuries, organs were built in concert halls and other secular venues, allowing them to be used in orchestras, as in Saint-Saëns’ Symphony No. 3 (called the Organ Symphony). The organ often plays a solo part, as in Joseph Jongen’s Symphonie Concertante for Organ and Orchestra, Francis Poulenc’s Concerto for Organ, Strings, and Tympani, and Frigyes Hidas’ Organ Concerto.

Other composers who used the organ in orchestral music include Gustav Holst, Richard Strauss, Ottorino Respighi, Gustav Mahler, Anton Bruckner, and Ralph Vaughan Williams. As concert hall organs could mimic orchestras, copies of orchestral music became part of the organ repertoire. With the rise of silent films, theatre organs were installed in theatres to accompany movies.

In the 20th century, both sacred and secular organ music continued to develop through composers like Marcel Dupré, Maurice Duruflé, and Herbert Howells. Others, such as Olivier Messiaen, György Ligeti, Jehan Alain, Jean Langlais, Gerd Zacher, and Petr Eben, wrote post-tonal (non-traditional) organ music. Messiaen’s work redefined how the organ is played and registered.

Albert Schweitzer studied the music of Johann Sebastian Bach and influenced the Organ Reform movement.

Film composer Hans Zimmer used a pipe organ prominently in his score for Interstellar. The final recording was made in London’s Temple Church on a 1926 four-manual Harrison and Harrison organ.