Cavaillé-Coll Nameplate

Aristide Cavaillé-Coll
Disposition II
Chest Placement, Manual Order, and Couplers

Chest Placement | Manual Order | Couplers | Review Quiz

Chest Placement

As a part of the organ's working mechanism, a Barker machine is not visible. Another innovation of the nineteenth century French organ does make a difference in the appearance of an organ:
Cavaillé-Coll removed the Positif division from the gallery rail and placed it behind the Grand orgue in the main case.
In Cavaillé-Coll's new organs the Positif no longer formed a separate visible component in the organ's visual design. When he was asked to rebuild an existing instrument, he often removed the Positif chest from its existing case and put it in the main case, leaving the old case empty of all but the façade pipes. His main goal, then, was not altering the appearance of the organ. If it had been, he could have just removed the old Positif case when he rebuilt an organ. He had a different goal - - changing how the Positif worked within an instrument.

In its older position, its stops had less power but more presence than those of the Grand Orgue. The sound of the Positif was lighter by virtue of the higher pitch level of its Montre, the fundamental principal stop. The other stops of the Plein jeu were designed in relation to this lighter fundamental stop.195 In spite of their relatively light weight, however, the stops of the French Classical Positif division had a strong impact on the listener in another way. They were placed closer to the listener, on the "audience" side of the gallery, so that their sound was heard directly, not diffused and reflected from walls and ceiling. This immediacy of sound meant that the Positif was not entirely subservient to the Grand Orgue. Instead, it was an independent division with its own strong character that enabled it to work with the Grand Orgue as a partner. The two divisions made equal contributions to the sound palette of the French Classical organ.

In the Cavaillé-Coll organ, instead of standing apart from the Grand Orgue, the Positif now occupied a physical position within the main case, usually behind the Grand Orgue chest. In that position, it no longer spoke with its former immediacy. Because its stoplist had changed only a little, it now spoke both more quietly and further away than the Grand Orgue. In its contribution to the sound palette of the Cavaillé-Coll organ, it was not a partner, but a junior officer, if you will. If you look at the three manual divisions of the typical Cavaillé-Coll organ, you will see that the Positif was still secondary in importance. It still had the foundation stops of the past, and the addition of a string, a harmonic flute and a trumpet allowed it to maintain a range of tone colors that paralleled that of the Grand Orgue. Now, however, its contribution to the sound of the instrument as a whole is best described as "preparatory." Its new function was to act as an intermediate sound level between the Récit and the Grand Orgue.

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Manual Order

The new role of the Positif was seen not only in the installation of its chest behind the Grand Orgue, but in another change Cavaillé-Coll made in the keydesk of his organs.
Cavaillé-Coll placed the Positif manual above the Grand Orgue, moving the Grand Orgue keyboard to the lowest position.

In the French Classical Organ the Positif keyboard was placed below that of the Grand Orgue, just as the Rückpositiv keyboard was below the Hauptwerk in a German instrument. In all such traditions, the division itself was placed behind the player so that it provided a contrast to the primary division in terms of volume, pitch level, and presence. Musical reasons, then, dictated putting the Positif behind the player. Furthermore, in all organ-building traditions where a division was placed behind the player, the keyboard for that division was placed below the keyboard of the primary division. The keyboard occupied that place for practical or technical reasons.

The practical reason for placing the manual in the lowest position was the path the trackers had to follow in order to run from the key to the windchest. In the diagram to the left, the green lines go from the top keyboard to the Récit chest, the blue lines from the keys to the Grand Orgue chest, and the red lines from the keys to the Positif chest. The trackers (and stickers) that go from the Positif keyboard to the Positif windchest run from the keys to the floor, then under the pedals and the bench before making another turn and leading into the Positif windchest. The trackers to the Grand Orgue go from the ends of the keys to a pallet box at the rear of the Grand Orgue chest, and other trackers run to the Récit between the two halves of the Grand Orgue chest. There is no crossing of trackers, so that both building and maintaining the action is simplified.

Cavaillé-Coll could have moved the Positif division behind the Grand Orgue and not moved the position of the keyboard. Using Barker machines for the Grand Orgue (such a large division that it needed the assistance) meant that running trackers to that chest no longer required a straight line. In fact, he could have used any one of a number of devices to run trackers from the lower keyboard to a chest behind the Grand Orgue without creating any conflict in the key action. His reason for moving the keyboard to a position above the Grand Orgue manual was related both to the musical function of the three divisions and to a different technical matter altogether: inter-manual couplers.

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Manual Couplers

Cavaillé-Coll's Récit was a greatly enlarged division compared to its French Classical ancestor, and the musical roles it filled had multipled along with the number of stops it contained. Its enclosure in a swell box meant that it had taken over the functions of the echo division, which Cavaillé-Coll no longer built. The Récit remained the third most important manual division, and its new stops and enclosure meant it could be used in a new way that took advantage of this configuration.

In a Cavaillé-Coll Récit, as in its predecessor the English Swell, the inclusion of a Trompette in the swell enclosure meant that the power of the reed stop could be dampened by closing the shutters. Then, even while the organist was playing music on the reed, the shutters could be opened, producing a crescendo and allowing the full sound of the reed to be heard. You've become accustomed to hearing this effect, and, in fact, you probably heard it in most of the organ music you encountered before you started studying the instrument and playing music written before 1850. In the first half of the nineteenth century, though, the controlled crescendo was a new concept in organ music. It must have been startling and exciting to the organists and composers of the day when they first heard it, and those very people who wrote and played music on Cavaillé-Coll's instruments made this particular sound and effect an integral part of their music.

The effect of a controlled crescendo using the swell enclosure was enhanced by the inclusion of inter-manual couplers that allowed each manual to be played by the ones below it. If all the couplers were engaged,

  • the Récit keyboard then played the Récit division,
  • the Positif keyboard played both the Récit and the Positif,
  • and the Grand Orgue keyboard, the lowest manual, played all three manual divisions.
The crescendo inherent in this arrangement of coupled manuals could be enhanced by using the swell shutters and the ventils194 in a standard way. Without moving his or her hands from the keyboards the organist could move through several dynamic levels.

Just as a closing example of how this all fit together in a Cavaillé-Coll organ -- the stoplists, the order of manuals, and the ventils, imagine a situation where these stops are drawn:

  • Récit foundations and reeds (fonds et anches).
  • Positif foundations (fonds), with reeds prepared (anches préparées).
  • Grand Orgue foundations (fonds), with reeds prepared (anches préparées).
If the player begins with the swell shutters closed, he or she would be able to produce this crescendo without touching the stop controls while playing.
  1. Begin on the Récit alone.
  2. Move to the Positif with Récit coupled.
  3. Move to the Grand Orgue with both Positif and Récit coupled.
  4. Open the swell shades on the Récit.
  5. Add the reeds of the Positif.
  6. Add the reeds of the Grand Orgue.
This new musical effect was available to organists for the first time around the middle of the nineteenth century, and it was an effect that could be accomplished only because Cavaillé-Coll
  • revised the stoplist of the traditional French organ,
  • placed the Récit division in a swell enclosure,
  • moved the Positif chest behind the Grand Orgue,
  • changed the order of manuals in the keydesk,
  • and made it easier to play with manuals coupled by using a Barker machine.

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© 2000 AD James H. Cook