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Glossary Of Organ Terms

Acoustics
The acoustics of a room are important to the success of a church organ for 2 reasons:
1. Congregational singing flourishes if the room is "live" (has no carpet or other absorbent material). A church organ is successful if it is associated with a singing congregation.
2. An organ depends on the room in which it is placed to supply resonance.
Borrowing, Duplexing, Unification
All 3 terms mean the same thing. A rank of pipes is ordinarily playable from only one keyboard unless the builder makes provisions to play that rank from a second keyboard or at a second pitch. For instance, a Great voice can be borrowed to play in the Pedal, or an 8' unison voice can be borrowed to play an octave higher at 4'. It is preferable to have independent pipes for each stop rather than to borrow.
Since borrowing is easier done with electric action than with tracker action, its overuse has contributed to the poor reputation of some electric action organs.
The term Duplexing was first used by builders who were able to make a rank of pipes play at two -- and thus duple -- pitches. The term Unification originated with builders who put all of the pipes into one spatial unit rather than separating them into Great, Positif, Pedal, etc. spaces. (See Werkprinzip)
Case, console, keydesk
A case is a wooden enclosure around the pipes which helps to blend and project the sound. The console is the cabinet with the keys and stop controls. It may be called a keydesk, particularly if it is attached to the pipe case.
Chest
A wooden box, containing wind, on which the pipes stand. Types of chests are differentiated according to the type of valves and stop action controlling admission of wind to the pipes.
There are three main types of chests:
Slider chest The usual tracker-action chest in which valves are connected directly to the keys with mechanical linkage (trackers) and stop action drawknobs are connected to sliders, which are thin boards extending the length of the chest and which must be in a certain position to allow wind to pass from the valves to the pipes. Slider chests in electric action organs use electromagnets or electro-pneumatic mechanisms to operate the key valves and sliders.
All-electric (electro-mechanical) chest A type of chest in which electromagnets move the valves which admit wind to the pipes.
Electro-pneumatic chest The type most frequently used from about 1900 until the present except for mechanical-action instruments. Each pipe, except for Mixtures, has an individual valve operated by a small leather-covered pneumatic motor, called a "pneumatic". Operation of the pneumatic is regulated by a small valve operated by a small electromagnet. Stop action is achieved by controlling current to the magnet or by controlling wind between the small valve and the pneumatic.
In addition there is the Pitman chest. A type of electro-pneumatic chest. Technically, the pitmans are small leather valves in the stop action which control wind leading to the pipe pouch pneumatics.
Each type of chest has its advantages and disadvantages. Both successful and unsuccessful instruments have been built using each type.
Combination Action
The system of presets, consisting of pistons (thumb buttons), memory unit, and drawknobs or stopkeys, by which the organist can draw on a predetermined combination of stops by pressing a piston. Older memory units were all-mechanical or a combination of electro-pneumatic and electro-mechanical relays. Modern memory units use solid-state electronics.
For a mechanical-action (tracker) organ to have a combination action, it generally must have electric-action stop controls. The sliders in that case have an electro-pneumatic or an electric motor which can be triggered by an electric signal from the stop controls.
Couplers
Console devices, similar to stop controls, of two types:
Intermanual coupler allows a keyboard to play the pipes of a second department. Example: Great to Pedal coupler allows the Pedal keyboard to play the stops of the Great department.
Intramanual coupler allows the stops on a keyboard to be played at a second pitch. Example: Swell to Swell 16' allows the stops on the Swell to be played from the Swell keyboard at a pitch one octave lower than normal. Swell to Swell 4' allows them to be played an octave higher than normal. Swell Unison Off, or Swell Original Pitch Off, keeps the stops from playing at their normal pitch.
Leather
Three main functions:
1. heavy fixed leather for valve facings;
2. heavy flexible leather for airtight joints in bellows;
3. thin flexible leather for small pneumatic motors.
All organs, including those with tracker action, use leather in some way.
The thin leather used on small pneumatic motors has a poor reputation for longevity. The life span depends on the tanning process and on the way the leather is employed by the organbuilder. Leather tanned before World War II is likely to last 50-100 years. Longevity is increased by coating the leather with silicone preservative. Plastic substitutes for leather are inferior.
Metal for pipes
Tin/lead alloy is the most frequently used metal. It is stable and easy to work. A high percentage of tin is associated with bright tone, and a high percentage of lead with dark tone. When metal with 40% to 60% tin cools after having been cast, the surface is spotted (spotted metal, s.m.). Because tin/lead is heavy, expensive, and soft, bass pipes are often made of copper, zinc, aluminum, or wood. Tin/lead is too soft for large, long pipes.
The type of metal is not as influential in tone quality as might be supposed. Sound is produced by the column of air oscillating in a pipe, not by vibration of the metal. The pipe itself contains and shapes the column of air. Care in design and voicing is more important than type of metal. Successful organs have employed every type of metal, just as have unsuccessful organs.
Mutations (Nazard 2 2/3', Blockflute 2', Tierce 1 3/5', Larigot 1 1/3', etc.)
Mutations are mildly-voiced stops which are added to a basic 8' stop to "mutate" or color its tone. For example, adding a Nazard 2 2/3' and a Tierce 1 3/5' to a Gedeckt 8' produces an Oboe-like tone.
Names of departments (divisions)
Portatif An organ small enough to be carried in a procession, thus portable.
Positif An organ too heavy to be portable.
Great, Hauptwerk ("main work" in German), Grande ("great" in French). Historically, a church's second organ, which was larger than the Positif. Thus, when 2 organs were combined into one instrument with 2 manual keyboards, the departments were called Great and Positif.
Swell A fairly complete department enclosed behind louvers which can be opened and closed from the console by the organist. Useful for accompanying.
Choir The English term for a small organ (Positif) which was used near the altar with the choir. The word may also be a corruption of the word "Chair", which was the English term for the Positif when it was placed behind the organist's bench or chair. The modern Choir organ is not as important to accompanying choir singers as is the Swell.
Names of stops
Bombarde French for an antique double reed instrument similar to a bassoon.
Cromorne Reed stop similar to but brighter than a Clarinet. German: Krummhorn.
Fagot German for "bassoon". Italian: Fagotto.
Floete German spelling of "flute".
Fourniture A Mixture (see below).
Gedackt, Gedeckt German for "stopped". A pipe with an air-tight cap or stopper at the top. It is only half as long as an open pipe of the same pitch, and it produces only odd-numbered harmonics.
Hautbois French for "oboe". Literally, "high wood".
Mixture Several ranks of small scale high pitched pipes playing together as one voice or stop which crowns the Principal chorus.
Nachthorn German for "night horn". A large scale flute stop, usually made of open, not stoppered, pipes. French for Night Horn: Cor de Nuit.
Plein Jeu French for "full ensemble". A Mixture.
Posaune German for "trombone".
Rohr- German for "tube" or "chimney". A Rohrfloete is a capped pipe with a little chimney soldered in the cap. The chimney emphasizes a particular overtone in the sound. A Rohrfloete does not roar.
Scharf A high pitched Mixture.
Sesquialtera A stop consisting of two ranks of pipes. One rank sounds the 2 2/3' pitch; the other sounds 1 3/5'. When combined with an 8' stopped flute, it creates a sound similar to that of an oboe.
Spitz- German for "pointed". A Spitzfloete is a tapered open pipe whose diameter is smaller at the top than at the mouth, thus making it appear to be pointed. A Spitzflute does not spit.
Organbuilder, functions of
Designer and musician: designs a musical instrument to serve the church's needs and wishes.
Contractor: builds a product meeting the design specifications. Does not make design decisions. The role of an organbuilder is different from that of other persons with whom a church deals, in that he designs and builds and is responsible for both. For this reason, securing bids for organs is not practical, as comparable bids would be possible only if detailed specifications for the organ were available to all prospective builders.
Pipes, types of by family
Principal (Principal, Diapason, Octave, Super Octave, Fifteenth, Montre, Prestant): medium scale open flue pipe blown strongly enough to develop a medium strong tone with a balanced blend of harmonics. Basic organ tone.
Open Flute (Harmonic Flute, Nachthorn, Waldflute, Blockflute): large scale open flue pipe. Darker, rounder tone than Principal.
Stopped (Gedeckt, Rohrflute, Koppelflute, Spillflute, Stopped Diapason, Bourdon): flue pipe of any scale with a cap or stopper at the top. A stopped pipe is physically half the length of an open pipe of equivalent pitch and is therefore often used instead of an open pipe for the lowest pitches where ever height is limited.
String (Viola, Salicional, Gamba, Dulciana, Celeste): small scale flue pipe. Brighter tone than Principal.
Reed (Trumpet, Oboe, Hautbois, Schalmei, Cromorne, Posaune, Bombarde, Bassoon): different in construction from flue pipes; produces tone by means of a brass reed which vibrates against a brass mouthpiece or shallot, just as a Clarinet or Saxophone does.
Pitch Designation
The number on the stop control indicates the length of the lowest, longest pipe in the rank, and that length determines the pitch of the rank. For example, if the stop control reads Principal 8', it means that the first pipe in the rank, low C, is actually 8' long. 8' ranks play normal pitch, the same as a piano. 4' ranks sound an octave higher, 16' ranks sound an octave lower, etc.
Rank, Stop, and Voice
A rank is a set of pipes, one for each note on the keyboard, all speaking with the same tone color. A rank of pipes produces one voice. The number of ranks, stops, and voices is the same except where there are multirank voices, such as Mixtures, in which one stop controls several ranks which play together to produce one voice. The Roman numeral with the name of a Mixture tells the number of ranks in that voice or stop.
The word "Stop" may be used to indicate either a voice itself or the console device used to turn the voice on and off. The term has an interesting history. The first organs did not have stop controls. That is, all of the ranks played all of the time, and there was no means of varying loudness or tone color. In about the 14th century, as organs grew larger, mechanical devices were introduced to turn off -- to "stop" -- some of the voices.
Rectifier
The electrical unit which supplies 12 volt d.c. for the organ action.
Scale
The word "scale" in the organ world usually refers to the diameter of a pipe or to the system of measuring diameters.
Regarding diameter:
Although a loud pipe or a loud organ may be called "large scaled", the fact is that scale can be determined only by actually measuring the pipes with calipers and rulers. In general, a large diameter pipe produces a round tone with few harmonics, or it can be blown harder to produce a strong tone with more harmonics. A small diameter pipe produces a brighter tone and cannot be blown as hard as can a large diameter pipe.
Regarding systems of measuring pipe diameters:
The builder either specifies the diameter of the first pipe of a rank and then gives a proportion by which succeeding pipe diameters are determined, or he gives the diameter of each C pipe (every 12th pipe) in a rank. In either case, the pipe maker computes the diameters of the remaining pipes.
Planning scales, along with voicing, is the very heart of the organbuilder's art.
Solid-State
This term actually refers to transistors, which are electronic elements which have no moving or gaseous components and are thus "solid-state". It has come to be equated with an organ's combination action, but the fact of the matter is that solid-state electronics is used in many different ways in modern organs.
Solid-state electronic components -- transistors and diodes -- are also used for relay and stop switching in electric-action organs and for control of slider motors in mechanical action organs.
To convert an old console to solid-state requires 2 separate units, a solid-state combination action and a solid-state switching system that interfaces the key and stop signals between the console and the chests. Conversion may also require replacing the stopkey actuators.
Temperature, effects of
All the pipes of an organ should be at the same temperature when they are played if they are to sound the correct pitch. The temperature should be the same as that at which they were tuned. Although the organ sounds out of tune when the temperature is different from when it was tuned—sharp if warmer, flat if cooler—all the pipes of the organ return to normal pitch when the temperature returns to normal.
If an organ is located in a building that has a heating/cooling system, it is important that the system be designed so that all parts of the organ receive air of the same temperature. It is best if the supply registers are higher than the highest part of the organ and return-air registers are lower than the lowest part. If one part of an organ receives heated/cooled air more slowly than the rest of the organ, a special ventilation blower should be installed to speed air movement to that remote section.
It is not necessary that an organ be heated or cooled all of the time. It is only important that air around the organ be brought to a normal temperature before the organ is played for public use if it is wished for the organ to be in tune.
The pitch of a pipe varies with temperature. Since it is the column of air in a pipe which oscillates, and since warmer air, being less dense, oscillates at a quicker rate, a warmer pipe speaks at a higher pitch than one which is cooler.
Historic European church buildings have no heating/cooling system because the range of temperature, summer through winter, is not as great as it is in the middle of the North American continent. Most North American buildings do have heating and cooling, and organs in American buildings consequently have more tuning problems.
Voicing
The techniques by which the parts of a pipe are adjusted to cause the pipe to speak.
The art of deciding the proper musical character (loudness, tone color, attack) of each rank of pipes and of adjusting the pipes to achieve the desired character.
Werkprinzip
The principle by which the departments ("Werk" in German) of an organ are arranged into distinct, characteristic locations. The Hauptwerk ("Haupt-" = head) is high and in the center, the Brustwerk ("Brust-" = breast) is below the Hauptwerk, the Rueckpositiv ("Rueck-" = back) is placed behind the organist, and the Pedal is split into 2 parts on each side. If there is another department at the very top of the case, it may be called a Kronwerk ("Kron-" = crown).
Where heating/cooling systems are a fact of life, as in the U.S., temperature differences at the different elevations require modifications of the Werkprinzip.
Wind
In talking about organs, the term "wind" refers to compressed air used to blow pipes. Wind is generated by a motor-driven centrifugal blower. Most church organs have a blower of from 1/4 to 3 horsepower.
The wind pressure is regulated by one or more wind pressure regulators (reservoirs, bellows). Constant wind pressure is required for pipes, as the pitch and loudness of each pipe is proportional to the wind pressure.

Revised 10/7/97

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