An Overview of Organs

How the Sound Is Produced

A Closer Look at the Pipes

Resources for Further Learning


It is impossible to talk about the organ without using alot of language that may be unfamiliar to you. This glossary should be helpful. If an unfamiliar word does not appear here, just send me the term to me and I'll add it to this list.


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Air Chamber
See the term wind chest.
1. Sight separations are made before notes in this style of playing. The organist decides the length of the separation and which notes to separate. An entire technique has evolved around this principle and is used in playing early organ music up through J.S. Bach and G.F. Handel.
2. Articulate can also describe a type of stop that has a clear attack point or chiff.
Attack Point
The moment at which the pipe begins to speak, when the key is pressed, is the attack point. Different kinds of pipes have a variety of attack points ranging from soft to strong and clear.
In older organs, before electricity, this was used to pump air into the reservoir. It was made of two wedge shaped pieces of wood joined by an expandable, fan-like piece of leather. Closing the bellows forced air into the Reservoir.

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Pipes that have a clear edge to the sound are often described as having "chiff." Any kind of pipe can have chiff but principals almost always have this clear attack point.
An electrical connection which, when charged, it magnetizes a piece of metal. This circuit is involved in the mechanism which opens the valves to allow pipes to speak in an electric action instrument.
Combination Action
The type of mechanism which controls the work of the pistons. One kind of mechanism is digital.
The unit that contains everything the organist needs to control the sound such as the manuals, pedalboard, pistons, etc. All this stuff together is the console. For a picture, see the overview page.
A coupler allows one division to be connected to another. This allows the stops of two divisions to be controlled by one manual or the pedals. For example, the Swell to Great coupler allows the Great manual to use stops from the Swell. There are also couplers which act within a division to play the stops at a different octave. For example, SW 4' is a coupler which will play the stops in the swell up an octave and at regular pitch at the same time.
Divisional Piston
It is a piston that affects only one division (See the next term). Each division on the organ will have sets of pistons that work only on that particular division.
The pipes are grouped into several separate sections called divisions. Each one has a name and is controlled through it's own manual or the pedalboard. There are several manual divisions and the most common are: Great, Swell, and Choir or Positive. There is only one Pedal division.
These turn the different kinds of pipe sounds on or off. Pulling the knob out turns the stop on and pushing it in turns it off. Some builders use stop tabs which flip up and down in place of drawknobs.

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Electric Key Action
In an electric key action, a wire, an electrical circuit and an electro magnet cause the valve below each pipe to open and close. When you press the key, you close an electrical contact. Electricity flows to the circuit which causes an electro-magnet to open and close the valves under each pipe. Electropneumatic action works in a similar way except that leather pouches are used in place of the magnet. These pouches create a vacumn which forces the valve to open.
This is a piece of metal which, when magnetized by an electrical circuit, attracts the valve below the pipe. The valve opens and air flows through the pipe, making the pipe speak.
Flue Pipe
This kind of pipe can be made of metal or wood. The sound is produced when the wind flows through the foot of the pipe and flows out the mouth (the hole in the front of the pipe). The air hits the lip of the pipe and causes the column of air to vibrate. The length of this column of air which, in turn, determines the pitch of the sound. The pipe's length determines the size of the air column. For a diagram of a flue pipe, see the sound characteristics page. Most of the pipes on the organ are flue pipes. The others are reed pipes. There are several types of flue pipes: Principals, Flutes, and Strings.
General Piston
This piston affects entire organ and is used to recall the organist's choice of stops and couplers from all divisions of the organ.

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Key Action
This is the mechanism the keyboard uses to used to control the pipe speech. It does this by controlling the air flow to the pipes. For more information, see How the Sound Is Produced. There are two kinds of key action: Mechanical Action and Electric Key Action.
1. In this style of organ playing, the notes flow smoothly from one to the next. Sometimes there are breaks between notes for musical phrases or to accentuate a note but the overall effect is smooth when compared to the articulate playing of the Baroque.
2. Legato can also refer to the kind of technique needed to play the notes smoothly.
This is the organ term for the keyboards.
Mechanical Action
The key is connected to trackers which eventually connect to the valves that open to admit air from the wind chest into the pipe. When you press the key, you are physically opening the valve in the wind chest. In mechanical action, there is one valve for each note on the keyboard. So, if the organ has 10 stops, there is one valve for all ten pipes which correspond to that note on the keyboard.
Memory Levels
In digitally controlled combination action, a memory level is like a file. Multiple level are essentially multiple files, allowing several different possibilities for one piston. See Solid State Combination Action.

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Pallet or Pallet Valve
When air flows to the pipe, it goes through a hole in the wind chest beneath the pipe. The pallet valve closes this hole when the pipe is not being used. Pressing the key will open this valve. Pipe valve is also another term.
This is the structure on the floor which contains the pedals and mechanisms which link them to the rest of the organ.
Pipe Beard
Used only in flue pipes, this is a metal rod that extends in front of the mouth and is connected to the ears. Large pipes need this extra piece to focus the tone because the larger mouth in these pipes makes the tone unstable.
Pipe Toe
This is the bottom opening of the pipe which rests in a hole on the top of the wind chest. See this page for a diagram of a pipe.
A piston is one of the numbered thumb buttons or toe studs on the console which can memorize a combination of stops. The organist can choose the stops to use by turning them on and then set them on one of the numbered pistons. (Most organ consoles have a Set button on the lower left corner of the bottom manual which is used for this purpose.) Then, the organist can recall those stops at any time by pressing that piston. There are general and divisional pistons.
Pitch in music is the note that sounds. On the organ, pitch does not always correspond to the key which plays the pitch. For more information on pitch and organs, see the Pitch Levels page.
Pluck Point
In mechanical action, this is the point at which the tracker is pulling the valve open. The organist can actually feel this through the key. It is similar to the pluck point in a harpsichord, which the musician can also feel when pressing a key.
A principal is one family of sound. It is a flue pipe which is rather narrow for its length and produces a bright, clear sound. There are many kinds of principals.

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A rank is a row of pipes. The row always has all pipes of the same kind of sound. For example, all the pipes for a Spitzflute (one kind of flute sound) will be in the same row. Organs are often described by the number of ranks they have. A 60 rank instrument is a fairly large size while an 18 rank instrument is small. Practice organs can have anywhere from 3 to 9 ranks.
Reed Pipe
This pipe is alot like a single reed orchestral instrument. The wind flowing through the pipe vibrates a metal tongue, a strip of flat metal, against an open-faced shallot. This is not visible from the outside because these parts are contained in the boot, the bottom part of the pipe which rests on the wind chest. The sound is amplified by the resonator, the top, flared part of the pipe. Pitch is determined by the length of the tongue. They have a strong, penetrating tone. ( Ritchie and Stauffer ) For a diagram, see the sound characteristics page.
This is a storage container for the wind. The top part of the container is expandable, like a fan or accordian. Weights or springs are used on the expandable part to keep the air under pressure. If the wind going to the pipes is not under the same, constant pressure, the sound will waver and the note will warble.
These are a convenience item and each one has only one function. Pressing the stud reverses what the current status of the stud was. If it was off, it is now on and vice versa. An example is a 32' Bourdon. This turns that stop on or off. Other examples are Full Organ which turns on all stops of the organ without the knobs or tabs physically moving, and Great to Pedal which is a foot control of the coupler.
In mechanical action, the keys are directly in front of the pipes and wind chest so the connection between the key and valve follows straight lines and right angles. Sometimes the architecture and space available necessitate the placing of the pipes off to the side. Then the connection must follow straight lines at irregular angles.
The roller, a wooden rod, is used in this circumstance as its rotation can accommodate the irregular angles. It has two arms at each end. One is attached to the key (or pedal) and the other is attached to the valve directly, or
trackers which lead to the valve. The roller mechanism is frequently used in the pedal division and is only found in mechanical action instruments.

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This is the proportion of the width of a pipe to its length. Tone quality of the pipe will change as the proportion changes.
This is a long wooden slat which has holes in it that correspond to a rows of holes in the top of the wind chest. It is used in a slider wind chest (see the next term).
Slider Chest
This type of wind chest uses a slider to block the holes in the wind chest and prevent the pipes from speaking. For a more detailed description, see How the Sound Is Produced.
Speaking Pipes, Pipe Speech
This is organ slang that means the pipe is making a sound.
Solid State Combination Action
This is a new technology that allows the memory of the pistons to be digitally memorized. There are multiple digital memory banks available up to 128 levels, depending on what the builder has installed. This means all the pistons can be "re-memorized" on multiple levels. For example, if the organ has 10 General Pistons and 32 levels of memory, there are 32 possibilities for GP #1, GP#2, and so on. The total possibilities for the general pistons are 32 x 10 or 320. These memory levels affect all pistons, generals and divisional pistons.
When notes are played short and detached, they are staccato.
1. The knob or tab which is used to turn a type of sound on or off (see Drawknobs).
2. A type of sound available on the organ. It usually has one pipe per note, although some kinds of sounds use several pipes for one note on the keyboard. Many stops on an organ result in many possibilities for tonal color and volume. There are several families, or groups, of sounds: Reeds, Principals, Flutes, and Strings.
Stop Action
This mechanism turns the stops on and off through the use of drawknobs on the sides of the console or stop tabs above the manuals. In turning a stop on, a barrier between the pipes and wind chest is moved aside so that air can flow to the pipe when its corresponding key is pressed. For more detailed information, see How the Sound Is Produced.
Stop Tabs
See Drawknobs.
Swell Pedal or Swell Shoe
A pedal on the console that controls the opening and closing of the swell shades.
Swell Shades
Slats which look like Venetian blinds that can be opened and closed through a foot pedal called the swell shoe. This allows volume control because pipes behind the blinds will get louder as the shades are opened. The shades are normally in front of the division called the swell. They can also be placed in front of the solo and choir divisions if the organ has these divisions.

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Technique in playing an instrument refers to all the physical movements and mental knowledge needed to play the instrument. All of these things are factual knowledge and can be taught to anyone. This is in contrast to artistry, which cannot be taught. Good technique is important because it helps the musician to express his or her artistic ideas. Organ repertoire uses two main types of technique: Legato and Articulated Playing.
Thumb Pistons
Just below the keys of each manual are small buttons. The numbered ones are pistons. The others have various functions and are reversibles. The thumb is used to press them which is how they got their name.
Tone is the color of the sound. The organ has a wide variety of sounds available. The difference in the sound colors of the stops makes this variety possible.
Toe Studs
These are the large buttons on the console near the pedals that control several mechanisms on the organ. On the right, there are a group of divisional toe pistons that only memorize stops for the pedal division. The group on the left is the general pistons which affect all stops and couplers on the organ. These are repeats of the thumb generals below the manuals. The last kind of toe studs you will see are called reversibles. These are usually spread out across the bottom of the console, above the generals and pedal divisionals. These are a convenience item and has only one function per stud.
1. Another name for mechanical action.
2. A tracker is also a long thin piece of wood used in mechanical action instruments to open the valve (See next term).
These open or close to admit air to the pipe. Their movement is controlled through the keys on the keyboard. Pressing a key down pulls the valve open. Each key has a spring underneath it so that the key returns to the "up" position, allowing the valve to close.
Voicing, Voiced
All pipes in a organ are altered after the organ is installed because acoustics of the room affect the organ's sound. Tonal color, volume, and stability of sound are affected by these alterations. For example, an unusually loud pipe that sticks out above the rest is softened until its volume matches the other pipes of that stop. Pipe organs are intentionally voiced for the following characteristics: Each note will sound slightly different in character, and the overall volume will increase as the notes go up the scale.
Wind Chest
The pipes sit atop this plain wooden box. When a stop is on, air flows from the reservoir into the box. When notes are played, it uses the air from this box to make the pipes speak.

An Overview of Organs

How the Sound Is Produced

A Closer Look at the Pipes

Resources for Further Learning

This site is part of the Organ Education Project.
© Copyright 1996-2001 by Marya J. Fancey