The pipe organ
I have collected information about the development and use of the instrument under the heading The History of the Pipe Organ.
I would like to present the specification and characteristics of pipe organs I know in order to aid the visitors of my web site to find the appropriate instrument and choose the most suitable concert.
Pipe organ, the “queen” of musical instruments
This “title” is duly attributed to this instrument since its sound is unmatched. What makes this characteristic sound quality? Here comes a little introduction to the operation of the pipe organ.
Imagine an orchestra. Many musicians play different musical instruments under the direction of the conductor. In organ music, the conductor is the organist and the different instruments are represented by the organ pipes. We can choose which “instrument” to play with the help of the registers (stops). We draw the stop “Flute” and the organ sounds like a flute. But there is a broad range of other instruments to choose from like trumpet, bassoon or viol. We might want to play all these simultaneously, just like an orchestra.
Organ pipes produce sound. Sound production requires air pressure. Our parents, grandparents may have been the ones who stood next to the organ and operated the bellows to blow wind to the pipes. Today, this mechanism is electrical. The engine admits wind to the windchest. From here, a system of valves allows air to flow into the pipes. Valves ensure that only those pipes will produce a sound which the organist wishes. The windchest, the valve system and the pipes are located in the casing.
The size of pipes varies from a few millimeters to several meters in length. Based on the way sound is produced by them, we distinguish between flue pipes and reed pipes. 85% of the pipes of an organ consist of flue pipes. Flue pipes work like flutes. They can be open, closed, conical, cylindrical, semi-closed etc. They are made of metal (tin/lead alloy or copper) or wood (the shape of wooden pipes is rectangular). Flue pipes include stops like principal, flute, octave, mixture, cymbal, salicional gamba, etc. Reed pipes are sounded by a vibrating brass strip called reed. Characteristic stops of reed pipes are trompete, oboe, regal vox humana, etc. The pitch of a stop is a function of length and is indicated by the length of the pipe: 8', 4', 2 2/3'.
The pipe organ cannot be imagined without the console. It consists of the manual or manuals (depending on how many manuals the instrument has) and the pedalboard. The collection of ranks controlled by a particular manual is called a division (Werke in German). Imagine that they are separate small organs which can be operated simultaneously. Some common English names of the best known divisions are:
Great Organ, Positive, Brustwerk, Oberwerk, Swell Organ, Pedal Organ.
The stop tabs are also located on the console. They are either plates or knobs made of wood, bone or plastic. The name and length are written on the stop. The roller crescendo and the pedal necessary for operating the swell shutters are also part of the console. Other pedals or the pistons aid the organist to operate certain stops (couplers) with the foot. Certain modern-day organs have an adjustable combination system which allows the operation of certain stops to be programmed. The action connects the console with the windchest. It can be mechanical, pneumatic and electric, depending on how the valve system is operated.
On of the most frequently asked question is how many pipes an organ has. The answer is not always evident since an organ may consist of several thousand of pipes. Let's calculate: an organ should have 85 times as many pipes as the number of stops. There is at least one pipe per stop belonging to each key of the manual. The manual has 58 keys, the pedalboard contains 30. An average organ has 20-40, smaller ones have 10-20 stops. But there are quite large organs with 80, 100, 150 and 200 stops. So how many pipes does a pipe organ have? Good luck with your calculations!
Organ Glossary
flue pipe: the air column is vibrated by wind driven through the windway and against the upper lip.
electric action: the valves are opened by an electro-magnet.
bellows: it produces constant wind and blows it into the windchest. It used to be operated by hand.
roller crescendo: an equipment which allows for pre-programmed dynamic changes.
console: the organist handles the keyboard and the pedalboard from here. It contains the stop knobs, the roller crescendo and all the combinations.
couplers: it connects the different manuals.
foot: it indicates the picth of the stop. The deepest pipe of the 8-foot stop is 8 feet (2.38 m) long and produces the sound C.
manual: keyboard encompassing 4-5 octaves (C-a''').
mechanical action: The keys are directly linked to the valves operating the different pipes by drawstop rods and roller arms.
scale: the proportion of the size (length and diameter) of the pipes. It determines the tone of the pipes.
reed pipe: the air column is vibrated by a reed, a flexible metal plate.
organ case: it contains the pipes, the windchests, the valve system and the motor.
pedalboard: keys played with the foot encompassing 2-2 ½ octaves (C-f’).
pneumatic action: keys, the windchest and the pipes are connected by a system of tubes.
swell shutters: this structure is operated by pedals, making possible the constant change of the dynamics.
register/stop: rank of pipes controlled by a single stop.
registration: the combination of different stops.
adjustable or Setzer combination system: it makes quick regsiter change possible, can be pre-programmed.
valve system: a system between the windchest and the pipes, it controls the wind driven to the pipes.
windchest: its main task is to collect the air under the pipes and direct the wind to the pipes. Each keyboard and pedal is linked to at least one windchest. Two major forms are the key-channel chest and the stop channel chest.
tracker action: the system connecting the keyboard with the windchest.