From the Builder
Discussions about building a special organ for Duke
University's Memorial Chapel began some twelve years ago. Since the room is
relatively small, the milder sound of the early Italian organ was considered a
most suitable complement to the large Flentrop and Aeolian organs in the main
part of the Chapel. Mean-tone tuning, customary for organs before the 18th
century, would also offer a wider scope of unusual musical opportunities. To
avoid diminishing even further the limited seating space, the new organ would
be placed in a "swallow's nest" loft made by the organbuilder to
match the organ case. A contract was signed in the spring of 1991, actual
construction began in the Brombaugh shop in the summer of 1995, and the organ
was installed in the Memorial Chapel during the summer of 1997. The result is a
new organ--consisting of 21 ranks, 23 stops, and some 923 pipes--that may very
well be the only modern example of its type in the Western Hemisphere.
The early Renaissance organs in southern Europe seldom made
the aggressive sounds that became common later in France and Germany. These
organs were remarkably simple compared to their northern cousins, but
(especially in Tuscany) they made a wonderful, sweet sound. Instruments in
Italy seldom had more than one manual keyboard, and the limited pedals, if
present at all, assisted only in playing occasional bass notes.
Nonetheless, these bass pipes could be quite large, as one
can still see in the 24' front
pipes of the Epistle organ in the
Basilica of San Petronio in Bologna. This remarkable instrument, made in 1475
by the renowned Tuscan builder Lorenzo da Prato, has only about a thousand
pipes, but the sound carries softly throughout the immense church. One of the
very few remaining organs from the 15th century, it underwent a minor
renovation in 1532 to accommodate retuning in mean-tone
style="mso-spacerun: yes"> temperament. The San Petronio organ--as
well as similar ones by Domenico di Lorenzo in Lucca and Florence, and by Giovanni Piffero in Siena--was the primary inspiration for the Principal chorus and two flute stops (4' and 22/3') on the main (Great) division of the Memorial Chapel organ. The Italian pipes are modeled specifically after extant examples from 1480, 1551, and 1612.
The Italian Principal chorus, referred to as the ripieno,
comprises several sets of narrow cylindrical metal pipes, of which the visible
front pipes are the largest. The lowest rank of façade pipes (Principale
8') extends from two octaves below middle c to two octaves above it. Additional
stops in the ripieno sound either an octave or a fifth higher in successively
higher registers and can be added separately in various combinations. The
smallest pipe of the highest rank, producing a pitch sounding four octaves
above middle c, is only 11/2≤ long, approaching the upper limit of normal
human hearing. Consequently, the usual Italian practice was to "break
back" the highest pitches to an octave below to avoid pipes that would be
too small for practical use. The Memorial Chapel organ includes a tiratutti
pedal to engage the entire Principal chorus at once, a device that appeared on
some Italian instruments by the turn of the 18th century.
In addition to the Principal chorus and the flutes in the
main division, another stop called a Cornettina (seen in later Venetian organs)
has been included. Containing a tierce, or third-sounding rank, it can be used
for solo melodies in the manner of similar treble stops found in contemporary
French, Germanic, and Iberian organs.
The Great also has two non-Italian flute stops (16' and 8')
and a German Trumpet 8' to expand the organ's versatility when playing
literature of other national schools. The Trumpet is divisible between bass and
treble, following a common historic convention in some instruments. The
division is found historically at various points near the middle of the
keyboard, but most commonly between b and c' or between c' and c#' (the latter
a consistent feature in Iberian organs). The Memorial Chapel organ features a lever that will allow the organist
to select either dividing point.
To make the organ still more flexible for playing a variety
of non-Italian music, a second manual division (in the style of a small north
German Brustwerk) adds four more stops. Of special interest is the Querpfeiff
2', inspired by an unusual overblowing flute stop with a similar name in the
Schnitger organ of the Jakobikirche in Hamburg.
The Brustwerk manual has the conventional bass "short
octave" format that was customary in keyboard instruments throughout
Europe before the 18th century. That is, the keys that would appear to be E,
F#, and G# in the lowest octave actually play C, D, and E respectively. The
Great keyboard is similar, except the apparent F# and G# keys in the bottom
octave are "split" to make those pitches available as well as the
D and E (an arrangement referred to as a "broken
octave"). The keys on both manuals reflect the shorter dimensions found in
early instruments.
The Pedal keyboard, however, has a different layout,
assuming a format often used by the renowned 17th-century north German builder
Arp Schnitger. This keyboard includes F# and G# in the bass octave but (like
the manuals) not C# and D#. The Pedal plays three of the Great stops by
transmission but has no pipes of its own.
The tuning system used in the Memorial Chapel organ is
mean-tone, the accepted standard for keyboard instruments in Europe during the
16th and 17th centuries. The most distinctive feature of 1/4-comma mean-tone
temperament is that the eight usable major thirds (plus two enharmonic ones)
are tuned absolutely pure, that is, without the audible "beats" that
characterize all intervals (except the octave) in modern equal temperament. For
long-established acoustical reasons, every practical tuning system involves a
certain quid pro quo. In this case, tuning some pure intervals creates other
unusable intervals, thus permitting only a limited constellation of keys
(corresponding to those commonly used in the repertoire at the time).
To allow composers and keyboard players to venture beyond
the usual limitations of mean-tone tuning, a few historic organs had more than
twelve notes per octave, extending the range of tolerable keys. This transient
system usually required double (split) keys for Eb and G# so that one could
also play the enharmonic notes D# and Ab. To ameliorate this rather curious
(and at times awkward) keyboard design for the player, we developed an unusual
(but not unprecedented) mechanical system for the Memorial Chapel organ so that
one can switch between the enharmonic pitches Eb and D# or G# and Ab on all
keyboards by means of two levers.
The organ case and loft for the Memorial Chapel instrument
follow basic Renaissance architectural styles. The upper case, containing the
pipes of the main division, is based on ancient Italian cases like the one in
the Church of San Bernardino in Verona as well as others found in some Tuscan
churches. The layout of the front pipes follows a conventional pattern seen,
for example, in the organ at Santa Maria della Scala in Siena. The façade
pipes are made of an alloy that is over 98% tin, and the pipe mouths are gilded
with 23-carat gold leaf.
Within the case, all the pipes rest on windchests. Although
most historic Italian organ builders used an unusual construction known as a
"spring chest," the more conventional European type, the "slider
chest," was occasionally found in Italy as well. The Memorial Chapel organ
employs slider chests, but the stops operating the Italian registers (located
on the left side of the keydesk) are fashioned after the ancient spring chest
levers.
The wind system includes one large wedge bellows and a small
electrical blower (the latter a minor concession to modernity). The wind
pressure is only 47 mm, considerably lower than was common for northern
European organs. The simple tremulant (after Schnitger) is adjustable in its
intensity. Components of the wind system, as well as the largest bass pipes,
are placed in a chamber behind the organ case, accessible by means of a spiral
staircase not visible to the audience or congregation.
--John Brombaugh
GREAT (Man. I)
16' style='mso-tab-count:1'> Bourdon
8' style='mso-tab-count:1'> Principale
8'
style='mso-tab-count:1'> Voce
umana (discant)
8' style='mso-tab-count:1'> Rohrflöte
4'
style='mso-tab-count:1'> Octave
(discant/full)
4'
style='mso-tab-count:1'> Flauto
in VIII
22/3' style='mso-tab-count:1'> Flauto in XII
2' style='mso-tab-count:1'> Fifteenth
11/3' style='mso-tab-count:1'> Nineteenth
1' style='mso-tab-count:1'> Twenty-second
2/3' style='mso-tab-count:1'> Twenty-sixth
1/2' style='mso-tab-count:1'> Twenty-ninth
1/3',
1/4' Thirty-third
& Thirty-sixth
style='mso-tab-count:1'> III
style='mso-tab-count:1'> Cornettina
22/3, 2', 13/5' [includes Flauto in XII]
8'
style='mso-tab-count:1'> Trumpet
(bass)
8'
style='mso-tab-count:1'> Trumpet
(discant)
BRUSTWERK (Man. II)
8'
style='mso-tab-count:1'> Oak
Gedackt
4'
style='mso-tab-count:1'> Oak
Flute
2' style='mso-tab-count:1'> Querpfeiff
8' style='mso-tab-count:1'> Regal
PEDAL (from Great)
16' style='mso-tab-count:1'> Bourdon
8' style='mso-tab-count:1'> Principale
8' style='mso-tab-count:1'> Trumpet
Great/Pedal coupler
Tremulant (adjustable)
Tiratutti pedal (ripieno)
Eb/D# and G#/Ab levers
b/c'-c'/c#' knob (Man. I)
Great: CDE-c''' (broken octave)
Brustwerk: CDEFGA-c''' (short octave)
Pedal: CDE-d' (after Schnitger)
Mechanical key action (suspended)
Mechanical stop action
Wind pressure: 47 mm
Pitch: one semitone below a' at 440 Hz
Temperament: 1/4 comma mean-tone
