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Glossary





Throughout this site are numerous words which will be unfamiliar to the average reader, this glossary is included with the intention of helping people to understand some of the terms used, and to therefore make the site more enjoyable.

A

A.G.O.
The American Guild of Organists. The A.G.O. is the professional association of organists in the U.S., founded in 1886. There are some 20,000 members. The A.G.O. web site has more details.

Action
The Action is the mechanism in the organ which transmits motion from the console to the appropriate part of the organ. For example, the Key Action is the mechanism which connects the manual keys with the pallet valve inside the wind chest.

B

Bellows
Leather or Rubber-cloth covered bellows were used in many reed organs to exhaust the air from the main reservoir, they were either foot-pumped, or operated by a handle on the side of the case. There are no bellows in the Apollo, though the term is often used to describe what is properly called the reservoir.

Blower
Instead of a bellows to supply the air (vacuum) the Apollo uses an electric blower. This actually sucks air, exhausting the reservoirs, but it is generally still referred to as a blower.

C

Chest
The Chest or "Wind Chest" is the part of the organ which contains the Pallet valves which let air flow through the reeds. The reeds therefore sit on the chest, which is sometime called the "Soundboard".

Chorus
A group of stops which belong to the same family of organ tone. The stops within the group are at different pitches which form what is known as a chorus. A small Diapason Chorus ideally contains Diapasons at 8', 4', and 2' pitches.

Cipher
A Cipher is a fault which causes a reed to speak when when no keys are pressed, generally this is due to a pallet valve which is not seating properly.

Combination Action
The mechanism which in some way, allows the organist to draw certain set stop combinations without drawing each stop manually. On the Apollo, this mechanism is in the form of brass pedals which draw set combinations of stops when pressed. Aslo referred to as "Composition Pedals", Audsley states this is a useless term as we do not "compose" our stops, but instead, combine them.

Compass
The range of a Keyboard or Pedalboard.

Composition Pedals See above

Console
The term console is used to describe all the parts of the organ which the organist directly uses when playing. The Apollo Console contains the 2 manuals, the Pedalboard, the Stops and the Composition pedals.

Coupler
Couplers never cease to confuse people who do not properly understand them. They are simple devices which come in several different types. Manual Couplers will link two manuals together. The Swell to Great coupler means that the Swell manual is "Coupled" (joined) to the Great manual. When the Great keys are played, the Swell keys will play also. Note that the coupler will only work in one direction - playing the Swell keys will not play the Great, - a coupler to do so would be labelled "Great to Swell". Octave couplers connect a Manual with the notes an octave above (on the same manual). The Swell Octave will play the notes an octave above those played manually when the swell manual is played. The Pedal Couplers "couple" or connect the Manual keys to the Pedal keys. Drawing the Great to Pedal will cause the Great keys to go down when the Pedal keys are played. Again, this mechanism will work in one direction only.

D

Diapason
The main "organ sound" of any organ. The Diapason reeds are of loud and full tone. They belong to the same family as the Principal reeds.

Division
A Division of an organ usually consists of a windchest and ranks (of pipes or reeds). The Great Division therefore consists of the Great Windchest, and the Great reeds which are controlled from the Great Manual. Divisions of the organ are sometimes referred to as seperate "Organs", for instance, the Swell Division may also be called the Swell Organ, both terms have the same meaning.

E

F

Flute Stop

A Flute Stop describes a rank of reeds which is trying to immitate a Flute stop on a pipe organ. True Flute Stops are only possible by the use of pipes, but reed organs have ranks of reeds which try to copy this quality of tone as far as is possible from a reed. Examples in the Apollo are the Swell Flute and Bourdon, and the Great Clarabella, the latter being the best specimen. Full Organ

This term is used to describe the sound of the organ with all the main chorus stops drawn.

G

Great

The name given to the main Department of the organ. The Great Department (sometimes referred to as the "Great Organ") contains all the main Chorus-work in the instrument.

H

I

J

K

Key

A balanced wooden lever which when depressed by the hands or feet, operates the organ action, and sounds a note.

L

M

Manual(s)

The proper term for the keyboard(s) played by the hands.

Mechanical Action

A mechanical action is one where the stops and manuals are linked directly to the reeds and pallets by mechanical linkages.This type of action is more commonly referred to as "tracker action".

N

O

Open (Diapason)

The term "Open" is prefixed to the stop name "Diapason" to indicate a rank of pipes which are open at their ends. This term obviously only applies to pipe organs, though the stop label is adopted in the Apollo. The tone of an Open Diapason is normal Diapason tone, the alternative being a stopped Diapason (sometimes, Stop Diapason, or Stop't Diapason) which is actually not of the Diapason family, but instead, a Flute Stop.

Organo Pleno

An alternative term to "Full Organ".

P

Pallet

The valve which opens when a key is pressed which admits wind (vacuum) to the reed(s) operated by the given key.

Pedal Clavier

Pedal Clavier, Pedalboard, or pedals. All terms which describe the keyboard which is played by the feet.

Principal

A Diapason stop pitched an octave higher, (4').

R

Rank

A term for describing a "set" of reeds, generally this set will extend the entire compass of the Manula or Pedalboard, and is controlled by a Stop. The term "stop" is sometime used instead, but it is generally clear whether it is the actual stop knob which is being referred to, or a rank of reeds.

Reed

Generally this referres to a piece of brass which vibrates when air is drawn across it. This is obviously the whole principle of reed organs. It is common though for the term 'Reed' to cover not only the brass tongue which makes the sound, but also the Reed Frame in which it sits. The term "Reeds" when in the context of organ registration, referres to those stops which are made to speak by a vibrating Reed rather than a Flue Pipe, obviously this only directly applies to pipe organs. Reed Frame

The brass frame in which the vibrating tongue sits. (see above)

Registration

Registration is the art manipulating and combining stops so as to produce the desired effect. Different registrations might be used to play different styles of music.

Reservoir

The Reservoir is the part of the organ where wind is stored and kept under pressure before it enters the Wind Chest. The Apollo has two reservoirs, one for the Great and Pedal Organs, and a seperate Swell reservoir. The reservoirs themselves are covered in rubber cloth, they are forced open by large springs. When the motor is turned on, the reservoirs collapse as the air is exhausted, and a constant vacuum is kept by the tension of the reservoir springs.

S

Soundboard

The Soundboard is generally the same thing as the wind chest. Thought whilst the Wind Chest describes the entire box which contains the Pallet Valves, the Soundboard may be seen more as the top portion of the Chest only, its job not being to store wind (vacuum) but instead to couple the vibrations made by the reeds to the surrounding air.

Specification

The details about the design of an organ. Usually comprising the list of stops and accessories, and any other important points which should be noted. With pipe organs, often pipes-scales (measurements) will be given.

Stop(s)

Also called Drawstop, Stop-knob, Register (or Stop register), Tab-stop, Stop-key. Whatever its name, this referres to the control the organist uses to turn 'on' and 'off' the desired Ranks. It can aslo refer to the rank of reeds associated with a stop. br>
String

Another family of organ tone. These Stops are so called because they produce a broadly similar sound to stringed instruments. Examples in the Apollo are the Swell Gamba, and Great Violone.

Sub-Octave

A Coupler which causes the notes one Octave below to be automatically played on the same Manual.

Super-Coupler

A Coupler which causes the notes one octave above to be automatically played on the same Manual.

Sticker

A thin wooden rod which is pushed by part of the action. Stickers are used to connect the Manual keys to the Pallet Valves on both Swell and Great Manuals in the Apollo.

Swell

The name given to the second Department of the Organ. The Swell Department (sometimes referred to as the "Swell Organ") contains the secondary Chorus-work as well as primary reeds etc... The Swell Reeds are contained in a box (Swell box) which is opened and closed by menas of the Swell Pedal. This effectively makes the sound "swell".

Swell Box See above

T

Tracker

A thin wooden rod which is pulled by part of the action. Trackers in pipe organ can be many feet in length where motion has to be transferred from the console to the Pallet Valves. Organs built with Mechanical Actions are said to have "Tracker Actions".

Tremulant

A Stop which engages a mechanism which interrupts the wind supply to the Wind Chest, causing a regular vibrating effect.







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