Winnetka Congregational Church, Winnetka, IL
Op. 18 is a 3-manual organ of 47 stops placed on the central axis of the reconfigured chancel of the 1936 church building. This placement allows the organ and choir to speak clearly into the main seating area. The organ is entirely encased in painted solid poplar casework. Its basic shape was inspired by the 1774 David Tannenberg organ at Holy Trinity Lutheran Church in Lancaster, Pennsylvania, an historic colonial building. The decorative pipe shades of butternut were designed by Kathryn Sparks and carved by Martin Pasi and Maurine Pasi. The case assumes the vital tonal function of blending and focusing the sound of the pipes, while also protecting them from dust.
The key desk and bench are made of white oak. The manual natural keys are covered with cow bone, the pedal naturals are oak, the sharps for the manuals are ebony and those for the pedals are cocobolo. The stop knobs are arranged in vertical jambs to either side of the keyboards. The stop knobs and toe pistons are Pau Ferro and the key cheeks are inlaid with bone and ebony.
The façade clearly represents the tonal structure of the organ. The pipes of the Great are at the center of the case while those of the Pedal division are placed on windchests divided on either side at impost level. The Swell is at the top center of the case, with its pipes enclosed behind expression shutters, rather like large Venetian blinds, just behind the case (façade) pipes. The Positive is cantilevered above the console in front of the Great in its own smaller case. This allows its sounds to project more intensely into the room, giving it a heightened presence to the listener. The twelve largest wood pipes of the Subbass 32’ stand on separate chests in the side balconies of the chancel.
The key action is entirely mechanical, the organist’s fingers directly opening the valves beneath the pipes through a system of levers and thin wood connections called trackers. This ancient system gives the organist intimate control over the speech and release characteristics of the pipes, for a sensitive control of musical phrasing and articulation, and through careful design and construction promises longevity measured in centuries. This is a so-called suspended key action, in which the keys are hinged at the rear and literally hang from the valves, or pallets, in the wind chests, which promotes a light and very responsive touch.
The stop action is electric, a solid-state combination action with sixty levels of memory providing for recall of numerous stop combinations. This state-of-the-art technology allows the player maximum flexibility in controlling the many tonal colors of the instrument.
The organ draws its principal tonal inspiration from the great North German organs of the 17th and 18th centuries, leavening its resources with several stops inspired by 19th and 20th century models. This enhances its flexibility in choral accompaniment and interpreting 19th century and later solo organ literature. Enclosing the pipes of the Swell division behind expression shutters affords the organist a more subtle range of dynamic control.
The four major families of organ tone, principal, flute, string and reed, are all well represented in the new organ. The principals are the foundation stops of any fine organ, a sound unique to the pipe organ. The tonal essence of the organ springs from the intense and vocal quality of the four façade Principals, with their clear, articulate speech under sensitive control of the mechanical key action. On each keyboard full choruses of principals (octave, quinte, sesquialtera, mixture, scharf), representing the higher harmonics of the sound, are developed above these façade pipes.
Flutes are represented in many forms and pitches (Bourdon, Gedackt, Spitzflöte, Rohrflöte, Waldflöte, Nasard, Gemshorn, Tierce, Harmonic Flute), the names reflecting both the shape of the pipes (stopped, tapered, stopped with chimneys) and their tonal function. On the Swell the family of flutes at the first five pitches of the natural harmonic series form a bold and yet sweet cornet registration.
On the Swell the Viola and its companion Celeste provide colorful string sound useful in choral accompaniment and Romantic organ literature, while the Salicional on the Positive adds a new and gentle color to that division.
The organ’s reed stops are quite varied, from the strong Trumpets and Posaune (Trombone), to the sweeter Oboe and Bassoon, and the Krummhorn and Dulcian, ancient forms of clarinet. The Vox Humana has very short resonators, and emulates the human voice. All but the Swell reeds are inspired by stops in the baroque organs of North Germany, especially those built by Arp Schnitger, who worked in the Hamburg area from about 1670-1720. The full and yet focused sounds of the Trumpet and Posaune are particularly representative of Schnitger’s work. The Swell reeds are inspired by similar stops in French classic and romantic organs, the piquant Oboe being modeled after 19th-century stops by the French master builder, Aristide Cavaillé-Coll.
All of the pipes, metal and wood, flue and reed, were made in the Pasi shop, from the casting of the tin/lead metal alloys through to the completed pipes. The majority of the metal pipes are made of 98% lead, with trace impurities of copper, bismuth and antimony, which help stiffen the metal. The string stops and Swell Octave 4’ are made of 90% tin, and the Octaves 2’ and mixtures are of 28% tin. The higher percentage of tin encourages a brighter sound. To enhance the intensity of the pipes’ sound, the metal is hammered following casting, which tightens its molecular structure. The Subbass 32’/16’ and the lowest 12 pipes of the Swell Quintaton are made of poplar, the only wood pipes in the organ.
The organ is tuned in the Kellner/Bach unequal temperament, which favors the keys nearer c major, and yet remains harmonious through all keys.
An electric centrifugal blower supplies wind to the organ, which is stored and regulated in two wedge-shaped bellows measuring 84 inches by 40 inches located on the ceiling of the choir room below the organ. This wind system imparts a gentle flexibility to the organ’s sound, allowing the pipes to sound more like a choir of human voices than an impassive machine.
Two special stops frequently found in Baroque organs lend a festive air to the organ. The Zimbelstern (Bell Star) has eight small bells struck in a repeating sequence. The Vogelgesang (Bird Song) is a single pipe placed upside down with its end submerged in a cup of water. It makes the sound of chirping birds when drawn.
The staff of Pasi Organbuilders constructed and installed the organ over a period of two years.