ORGAN TYPES AND COMPONENTS


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INTRODUCTION

The modern pipe organ is a time-honored musical instrument that makes use of mechanical, electrical, electronic, and/or pneumatic (air-driven) components. A BLOWER supplies air through WIND LINES and RESERVOIRS to WIND CHESTS, where air is kept at a certain pressure for use on demand. The wind chests contain valves that open or shut the air flow into the PIPES, which set atop holes in the chests. Once a pipe is sounded, it can be softened in effect only if it is part of an ENCLOSED division (contained in a box with louvers). The louvers may be closed, thereby softening the sounding pipes (like closing the door on a practice room) by closing the EXPRESSION PEDAL. An enclosed division is also known as an "expressive division," whereas an EXPOSED division (all sides are open) or an ENCASED division (only one side is open) are called "non-expressive divisions." If the pipe is part of an exposed or encased division, it cannot be made to sound louder or softer by the organist. But an exposed, encased, or enclosed division can be made louder or softer by adding or retiring stops, thereby increasing the number of pipes sounding per key depressed.

COMBINATIONS of stops may be pulled by hand, or may be set into memory and recalled through the use of the COMBINATION ACTION (including the THUMB PISTONS, TOE STUDS, SET BUTTON, and MULTI-LEVEL MEMORY).

The pipe organ consists of several major components:
  1. WIND SUPPLY--the blower, wind lines, and reservoirs that make a steady supply of pressurized air available for any pipe at any time.
  2. WIND CHESTS--wooden boxes upon which the pipes set, containing valves and other selection devices that control the air flow into the pipes.
  3. PIPE WORK--pipes of metal or wood of various sizes and shapes that produce tones of various pitches and tone qualities. Pipes are arranged in ranks (sets) of one pipe per key (61 pipes per manual rank, 32 per pedal rank). Ranks are grouped into 2, 3, or more divisions (Great, Swell, and Pedal, for example).
  4. CONSOLE--the control center of the organ, where the key and stop actions originate, where other assisting devices are controlled (the expression and crescendo pedals, for example), and where the combination action is housed.
  5. STOP ACTION--the means of selecting sets (ranks) of pipes from which an individual pipe will be sounded whenever a key is depressed (mechanical, electric assist, electric, or pneumatic). Stop tabs are lined up in a "stop rail" above the highest manual; stop knobs are located on the key jambs on either side of the manuals. A stop is "pulled" to activate the rank(s) with which it is associated, or "retired" to deactivate the rank(s).
  6. COMBINATION ACTION--a memory system allowing instant recall of various combinations of stops at the touch of a button (thumb pistons or toe studs).
  7. KEY ACTION--the means of connecting the key with the valve underneath the pipes (mechanical or "tracker" action, electric action, pneumatic action, or electro-pneumatic action).
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THE ORGAN CONSOLE

The CONSOLE is the control center of the organ. The organist pulls a STOP (a flute, for example) to potentially activate a RANK (set) of pipes that belongs to a particular DIVISION of the organ (the Great, Swell, or Pedal, for example). That division is played from a certain MANUAL (a keyboard for the hands) or from the PEDALS (a keyboard for the feet).

The single pipe that sounds middle-C from that rank will sound only if the stop for that rank is pulled AND the KEY middle-C on the appropriate manual is depressed. In other words, when the key is depressed, a valve underneath the pipe opens, allowing air into the pipe IF the appropriate stop has been pulled. The KEY ACTION (mechanical, electric, or electro-pneumatic) has some influence over the manner in which the pipe speaks. A pipe produces sound as a column of air vibrates (like a whistle--called a FLUE pipe) or as a reed vibrates (like a clarinet--called a REED pipe).

COMBINATIONS of stops may be pulled by hand, or may be set into memory and recalled through the use of the COMBINATION ACTION (including the THUMB PISTONS, TOE STUDS, SET BUTTON, and MULTI LEVEL MEMORY).
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Organ "Keyboards"--Manuals and Pedals
The piano has one keyboard. The small standard church organ has three--two manual keyboards of 61 keys each, called "manuals" for short, and a pedal keyboard of 32 keys, referred to as "the pedals." The first manual, the lower one closest to the performer, is "the Great," while the second manual, the upper one, is "the Swell." Each manual and the pedal keyboard corresponds to its respective "division" of the organ. A division consists of several ranks (sets) of pipes located within close proximity to one another in the organ case.

THE GREAT DIVISION: This first and lower manual (located closer to the performer) controls the main division of the organ, referred to also as "the Great." The main principal chorus, often considered the "backbone" of the organ, is central to the Great division. This is usually a non-expressive division, meaning that its pipes are not contained in a box with louvers that can be opened and shut. In that case, volume can only be controlled by the addition and retirement of Great stops. However, some church organs are installed with most of the organ pipework--even the Great--contained in the swell box.

THE SWELL DIVISION: This second and higher manual (located just above the Great) controls a secondary division of the organ, referred to as "the Swell." A secondary, more flute-dominated chorus, and a fiery reed (trumpet) chorus are often characteristic of the Swell division. By definition, the Swell is an expressive division, meaning that its pipes are contained in a large box with louvers that can be opened and shut. An EXPRESSION PEDAL (also called the SWELL PEDAL) controls the position of these louvers. Volume can also be controlled by the addition and retirement of Swell stops.

THE PEDAL DIVISION: The pedal keyboard contains keys that correspond to the first 32 keys of the manual keyboard (C to g"). Middle c, therefore, is the right-most pedal c. While the basic pitch of the manuals is concert pitch ("eight-foot pitch"), the basic pitch of the Pedal division is one octave below ("sixteen-foot pitch"). The deep vibrations that can be felt and that are so typical of the large pipe organ are characteristic of the Pedal division.

At either side of the manual keyboards are wooden frames called KEY CHEEKS. The key cheeks for the lowest manual can be grasped by both hands for steadiness when playing pedal solos or exercises. Some organists prefer to rest the hands on the bench to either side of the body, resulting perhaps in a less stable position but a more relaxed appearance when playing pedal solos.
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The Expression ("Swell") Pedals and the Crescendo Pedal
The tilting pedals, located above the pedal keys, offer two completely different ways of affecting a crescendo or diminuendo. The difference between their functions should be understood thoroughly.

THE EXPRESSION ("SWELL") PEDALS control volume by opening and closing louvers. These louvers are the only opening of a large box containing a division of the organ. (On a 2-manual organ, this is the Swell division, but occasionally some ranks of the Great and Pedal divisions are contained in the Swell box. In addition, 3- and 4-manual organs often contain an enclosed Choir and/or Solo division.) As a rule the expression pedal it is located just above pedal (tenor) e and f. The normal position for the swell pedal of a pipe organ is fully open (the top of the pedal "to the metal," like the accelerator of a car) in order to sound in proper balance with the Great division. However, it can be closed quickly or slowly for expressive effects, or to adjust the balance between certain Great and Swell combinations.

On some electronic organs the swell pedal serves as a volume control for the entire organ--not just the Swell division. On others there may be a separate expression pedal that controls the Great and Pedal divisions. In both of these cases the expression pedals work like the volume control of a radio. If distortion occurs when these volume controls are fully open, its optimum position must be determined by trial and error every time the organ is played. However, a technician can regulate most electronic expression pedals to avoid distortion so that "full open" might approximate the "full open" volume of a pipe organ.

The expression pedal is most conveniently operated by the right foot, but the left can be used if the right foot is busy. Often the most dramatic crescendo effect occurs as the louvers first begin to open, so a smooth crescendo may require a very gradual opening at first, with some acceleration following. If a long crescendo or diminuendo is required while both feet are called upon alternately to play, place the free foot on the expression pedal and open or close it as smoothly as possible in small "installments."

THE CRESCENDO PEDAL controls volume by adding and retiring stops electronically in a pre-determined order. If the organ is so equipped, the crescendo pedal is located just to the right of the expression (swell) pedal, and is often raised slightly to help identify it "by feel." As the pedal is opened, the softest stops are added one by one, maintaining some balance between the divisions. When fully opened, nearly all the stops that contribute to the ensemble are added. As the pedal is closed, the stops are retired in reverse order. Only the stops that are physically drawn will remain sounding when the crescendo pedal is fully closed. The normal position for the crescendo pedal is fully closed (the top of the pedal pulled back towards you). Due to the organist's limited control in determining the stops that are brought into use with the crescendo pedal, and due to the infrequent use it finds in organ literature, the crescendo pedal is used far less often than the expression pedal. Some organs have no crescendo pedal at all.

In order to operate either the swell or the crescendo pedal with optimum control, place the foot flat on the pedal and adjust its position with the entire foot, not just the toe. The operation of these pedals should be considered from the time you begin working out the pedaling of an organ piece. Practice operating these pedals as diligently as you would practice the notes, and allow the ear to guide the feet towards a musically satisfying result.
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Stop Action
The earliest organs (into the fifteenth century) had grown to the point that several pipes sounded whenever a key was depressed. It was the idea of "cutting off" or "stopping" selected pipes from sounding that resulted in the term "stop." In modern organs all stops are actually devices that select sets (ranks) of pipes from which an individual pipe will be sounded whenever a key is depressed. STOP TABS are lined up in a STOP RAIL, usually located above the highest manual. STOP KNOBS (and occasionally stop tabs) are are located on the STOP JAMBS on either side of the manuals. A stop is "pulled" to activate the rank(s) with which it is associated, or "retired" to deactivate the rank(s). Like key actions, there are several types of stop action:

MECHANICAL stop actions use stop knobs or levers only (not stop tabs). When the stop knob is pulled, a mechanical linkage between the console and the windchest brings a rank of pipes into potential action. Like mechanical key action, this is the oldest type, and offers a more "honest" form of contact between the organist and the music. However, mechanical stop actions are difficult to control by most types of combination action (see below). They also require a reasonably close proximity between console and pipework.

ELECTRIC ASSIST stop actions use electric motors on the windchest to help move the stop action. The connection between stop knob or stop tab and the windchest is electric, so the console can be separated from the pipework.

ELECTRIC stop actions replace all mechanical stop action parts with electrical contacts and magnetic valves. The console can be located away from the pipework. Lighted rocker tabs, found in some electronic organs, would be included in this category.
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Key Action
When a key is depressed, a valve opens underneath a particular pipe. The means of connecting the key with that valve or "pallet" is called the key action. Most organs are designed with some form of the following types of key action:

MECHANICAL (“TRACKER") key action, the oldest type, features a mechanical connection from the key to the valve (or "pallet"). This action is usually designed with lengths of wooden "trackers" and roller bars to distribute the action to the proper pipe. Since the organist is opening the pallet through a truly mechanical connection, he enjoys a small amount of control over the way the pipe begins to speak. This is one important benefit of tracker key action. The console must be located close to the pipework, however, for the key action to remain tight and responsive. (Shorter trackers make possible a more responsive action.) But this is rarely the best position for hearing the organ as the choir, congregation, or audience would hear it.

DIRECT ELECTRIC key action utilizes electrical key contacts and magnetic pipe valves. Since the action is not mechanical, any control over the pipe speech is sacrificed. In fact, the magnetic valve opens even more abruptly than with a tracker or electro pneumatic action, resulting in a somewhat harsh initial attack as each pipe sounds. The console may be placed any distance from the pipework without affecting the responsiveness of the action, allowing for more favorable console placement. Direct electric actions are less expensive to produce than mechanical or electro-pneumatic actions. Electronic organs always use electric key action.

ELECTRO-PNEUMATIC key action combines air pressure and electrical circuits in the connection between key and pipe valve. The organist has no contol over pipe speech, but the harsh initial attack of the direct electric key action is minimized in an electro pneumatic key action. As in organs with direct electric key action, the console may be separated from the pipework. Electro pneumatic key actions tend to be more difficult to maintain than either of the other two types.
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Pistons (Pre-sets) and the Combination Action
The art of organ registration (the selection and combination of organ stops, or "registers") has been facilitated greatly by the invention of mechanical, pneumatic, electrical, and now solid state combination actions. In the era of organ performance prior to this, the organist was required to make all stop changes by hand, or to recruit one or more registration assistants. Obviously, this inflicted a great limitation on the types and number of changes in organ sound that were possible in the course of a performance--even with the help of an assistant. In modern times many organs are built with a combination action, making possible the setting or "memorization" of any combination of stops, and the possibility of recalling that combination by pressing a single THUMB PISTON or TOE STUD. Of course, the combination action is used to facilitate stop-changing. It should not be used for stop changes that can be made just as easily by hand--a basic skill required of every organist.

Here are the components of the combination action. Learn how the system works by trying it on your instrument:

1. THUMB PISTONS. Most organs have several buttons underneath the manuals that are labeled with numbers. These THUMB PISTONS are your contact point with the combination action. When pressed, each of these pistons recalls the combination of stops that it was most recently called upon to remember. These are called GENERAL PISTONS ("generals"), because they memorize and recall stops on all divisions. Generals are usually located to the far left or to the center underneath one manual or the other. LOCAL PISTONS ("locals") memorize and recall only the stops on one division. The Swell locals are located underneath the Swell, those for the Great are found underneath the Great, and those for the Pedal are usually on TOE STUDS to the right of the crescendo or expression pedals. However, toe studs more often function as duplicates of the general thumb pistons, offering the choice of using the feet when the hands are too busy to reach a thumb piston. Most organs have USER-ADJUSTABLE pistons, where new combinations may be set on pistons by the performer as desired. Some organs, mostly older electronic organs, are equipped only with FACTORY PRE-SETS, meaning that the combinations recalled by the pistons are pre-set at the factory, and cannot be changed by the performer. In this case, you will not find a SET BUTTON (usually labeled with an "S", and usually the lower left-most thumb piston) and any attempts at resetting a piston will be futile. Still other organs, particularly very small ones and many organs with mechanical key and/or stop actions, have no combination action at all. In this case, any registration change must be made by hand either by the performer or with the help of a registration assistant.

2. SET BUTTON. The function of the set button is best learned by using it. Press the CANCEL button. Choose the following stops: Pedal Principal 16' and Octave 8'; Swell Trompette 8'; Great Principal 8' and Octave 4'. Press the SET button and hold it in while you press general piston 3. Now release both. See if your combination is set correctly by retiring all stops, or by pressing the CANCEL (marked by the number "0") button. Any indication that a piston or stop is selected should be blank. Play a chord and see that nothing is playing. Now recall your combination by pressing piston 3 without pressing the set button. The stops you chose should now be selected. Play a chord on the Swell--you should hear the 8' Trompette. You should hear your Principal 8' and Octave 4' on the Great, with Pedal 16' and 8' stops to balance. If not, perhaps you didn't hold in the set button, or didn't retire the stops, or have pressed some piston other than the one that was set. Try it again if you were not successful the first time.

On most instruments, the piston allows the organist to see what was set on it. However, on some organs there is no way to identify the stops that were drawn and set on any piston other than by using trial and error, your ear and your memory. Let's refer back to what was set for piston 3, and set a slightly bigger combination on piston 4. Remember the stops we set on piston 3 (check yourself by looking in the paragraph above) and draw them again. Now add to that combination on the Swell: Prestant 4' and Nazard 2 2/3'; on the Great: Super Octave 2'; and on the Pedal: Great to Pedal. Press the SET button and hold it in while you press piston 4. Check yourself: retire all stops, recall the combination by pressing piston 4 and playing a chord. Is the combination on each manual a bit bigger than that of piston 3? Try it by pressing piston 3 and by playing a chord, then while holding the chord pressing piston 4. Now cancel, draw all the stops used for piston 4, and add a stop that will give the Great a little more brilliance. Set the new combination on piston 5 and check yourself in the same manner as before, but expecting an increase of brilliance in the Great and the Pedal only (the Swell has not been changed from piston 4 to piston 5). Now turn off the organ, wait a few seconds, and turn it back on. Check your pistons, and note that they survived the power outage. Organs are designed to remember the combinations even after being powered down.

3. MULTI-LEVEL MEMORY. Press the thumb piston called "M[emory] 2." Clear all stops and press piston 3. Do you hear the Swell Trompette 8'? Probably not. Piston 3--and all of the others--remembers the combination you set on memory 1 (which is in force when the memory 2 piston is disengaged) and some other combination for memory 2. We say that the organ has a multi-level memory, or two memories. Frequently a standard buildup, much like our progression from piston 3 through piston 5, will be set and kept on one memory, reserving the other(s) for customized combinations. The computer age has made possible anywhere from two to literally hundreds of memories on a single organ. Multiply the number of memories by the number of (general) thumb pistons, and you have the total number of possible combinations that can be set. If an organ has 6 pistons and 2 memories, it has 12 combinations total. If there are 15 pistons and 4 memories, 60 combinations are possible. 10 pistons and 8 memories yield 80 combinations. At the Salt Lake Tabernacle, with so many staff and guest organists, there is great need for many combinations. The organ has 20 pistons and 255 memories. How many combinations are possible? (5,100)

4. COMBINATION LOCK-OUT. Some combination actions include a device to help protect your combinations from accidental (or not accidental) loss of your pre-set combinations. This may be a keyed lock (many pipe organs use this type), or a button with the word "lock" or something similar. If you need to set combinations on the keyed-lock type and the key is missing, the organist should be able to provide you with one. If not, write to the organ manufacturer for replacement keys (most locks use theby the same manufacturer use a standard key). When the key is turned, the combination action can be re-set. When the key is turned back and can be taken out, the combination action is locked in and no pistons can be set.
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Reversibles
Although they appear identical to thumb pistons and toe studs, "reversibles" serve an entirely mechanical function independent from the combination action. The oft-used Great to Pedal reversible can serve to illustrate. When it is depressed the first time, the Great to Pedal coupler is drawn (in most cases the drawknob or stop tab actually moves into "on" position). When depressed the second time, the action is "reversed," retiring the coupler back into "off" position. Depressing a Great to Pedal reversible repeatedly simply brings the drawknob or stop tab in and out or up and down.

The Great to Pedal reversible is especially useful in maintaining a balance between manual and pedal. If you are playing on the Great, your pedal combination might include Subbass 16', Swell to Pedal, and Great to Pedal. If you change manuals from Great to Swell, balance can be achieved simply by depressing the Great to Pedal reversible, which retires the Great to Pedal, and leaves only the Subbass 16' and the Swell to Pedal. As you return to the Great, you depress the reversible again and the Great to Pedal coupler is drawn. Of course, the coupler can also be drawn or retired by hand--without use of the reversible.

Although the Great to Pedal is the most common reversible, there are others. The "Sforzando" or "Tutti" reversible, often marked "SFZ" or "T", brings on all stops that contribute to the ensemble--essentially full organ. The Sforzando reversible is usually designed to add the final crowning glory to the fully open crescendo pedal. The combination that is brought into action by the Sforzando reversible can usually be adjusted by a technician. If it is too shrill to be usable, work with your technician. First try having the organ tuned (or at least the higher-pitched stops and the reeds). If it is still too shrill, see if a supercoupler or a very high pitched stop can be eliminated from the Sforzando reversible.

The Great to Pedal and Sforzando are the only reversibles common to small organs. Larger instruments may include reversibles for the Swell to Pedal and other couplers, as well as other important stops or devices.
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Adjustable Bench
Due to the great variation in leg length from person to person, some means of adjusting bench height is required if several organists are to share a single bench. Most organ benches are cut to an average length, meaning that only those with medium-length legs will be able to play with a proper position at the organ. Those with longer legs will have to lean back to lift their feet up when moving from key to key. Lower back pain is a common complaint of taller organists who do not have an adjustable bench. Some relief can be achieved for taller organists by sliding one or two 1" x 4" boards underneath each bench leg. This will bring the distance from the top of the bench to the pedal key surface more in line with the length of the leg from the knee to the heel.

Those with shorter legs will tend to slide forward on the bench to reach pedal keys. This results in serious organ playing problems. It is impossible to balance when an organist must slide forward. Some very short organists, in order to avoid slipping forward onto the pedals, have to dedicate one foot to supporting the body by pressing against the pedalboard framework. Such extreme measures result in choppy, one-footed pedal technique. Short-legged organists who do not have to slide so far forward often avoid playing the heels because they must press the leg into the bench--and even raise the body upward--to get the heel down far enough to play the key.

Ideally an adjustable bench should be purchased when several organists of various heights play a single instrument. If this is impossible (they cost approximately $1000), each leg of the bench should be cut down at least 3/4", then special bench risers or four finished 1" x 4" boards should be provided to bring the bench back up to standard height or 3/4" higher for taller organists.
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THE ELECTRONIC ORGAN

The pipe organ produces sound by directing a steady supply of air through specially-designed pipes. It requires one pipe per key, 61 pipes per manual rank, and approximately 9 ranks for the smallest church organ. At $10,000 to $20,000 or more per rank, a pipe organ becomes a major investment. Due to the great initial expense of such an instrument, attempts have been made to economize wherever possible. With the advent of electronics came the idea of substituting an electronically-produced tone for the tone of a sounding pipe. In recent years, a side-benefit of the rise of the computer has been the capacity to "digitally sample" pipe sound (to approximate it through digital reproduction of the wave form).

The most advanced electronic organ today is still, at best, an electronic substitute for the true pipe organ sound. But the increased accessibility offered through lower initial cost, smaller size, and relatively easy transportability has resulted in their placement in numerous homes, churches, colleges, and even some concert halls.
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