ABOUT THE INSTRUMENT

• The modern pipe organ consists of one or more
manuals (keyboards) and a pedal keyboard.
These control several hundred sets of pipes
called ranks.

• Each manual affects particular groupings of
ranks called a division or organ (a set of
approximately 61 pipes). The sets of ranks
within a division possess particular tone qualities
designed to complement each other. Certain
divisions are assigned to particular manuals and
are generally organized in the following ways
(according to the number of manuals):

• The various tone qualities of the ranks within a
division are controlled by stops, which allow the
pipes to sound. When a stop tab for stop knob) is
"on "it is "drawn."

• Most organ stops are listed by name and the
number of the pipe length, which determines
the sounding octave: 8' (unison), 4' (an octave
higher), 2' (two octaves higher), 16' (an octave
lower), 32' (two octaves lower, pedals only) and
64' (three octaves lower, pedals only).

• The following classes of tone qualities of the
ranks are found on most pipe organs:

>• Foundation Stops: These metallic-sounding
flute stops are usually included on every
organ. They are the most organ-like tone
quality found on the instrument.

>• Flute Stops: These produce a flute tone with
a strong fundamental and few upper partials.
They are the largest pipes on the organ.

>• String Stops: These are flute stops that are
stronger in the upper partials.

>• Hybrid Stops: These stops are combinations
of both the foundation and flute stops, or
flute and string stops.

>• Chorus Reed Stops: Although named for
specific instruments (oboe, trumpet), these
stops do not imitate them. They possess a
buzzy tone quality and are good in a solo or
ensemble context.

>• Solo Reed Stops: These solo stops are meant
to sound like the instruments for which they
are named (orchestral oboe, clarinet, French
horn, etc.).

• In addition to the above stops, the following
devices are intended to modify tone colors or
create new ones:

>• Mutation Stops: These stops are based on
partials in the harmonic series that are not
based on the octave. They reinforce partials
that sound at the 3rd, 5th, 7th and 9th.

>• Mixtures: These stops mix various ranks
together to sound simultaneously. The tone
qualities and pipe lengths may vary from
mixture to mixture or even within a mixture.
Because a combination of different pipe
lengths are employed, resulting pitches may
change depending on the octave played.

>• Tremulants: These produce an effect much
like the vibrato of the human voice.

>• Celesta Pipes: A pair of pipes (usually 8') in
which one is tuned slightly sharp to produce
a tremolo effect.

>• Double Pipes: Similar to the celesta pipes,
this double pipe is tuned so that one half of
the pipe is slightly flat and the other half is at
unison or slightly sharp.

>• The Swell Box: Pipes from a division, usually
the swell, are encased in a large box with a
movable shutter. When the shutters are
opened, more sound is allowed to exit the
box. It is operated by a foot pedal called a
shoe.

> The Crescendo: Also operated by a shoe, the
crescendo increases the volume by adding
stops as the shoe is depressed. When fully
depressed, all stops are sounding. This
device is good for adding accents and
highlights.

>• Couplers: Couplers link the stops of one
manual to another or the pedal stops to a
manual. Couplers vary according to the
number of manuals on the instrument.
The following couplers are common:

Swell to Choir, Swell to Great, Swell to Pedal,
Choir to Great, Choir to Pedal, Great to Pedal.

 GENERAL CHARACTERISTICS

• Pipe organs vary according to the design,

number of manuals, number of pipes, and tonal
qualities of the pipes. The design and building of
a pipe organ is an individual and personal art.

• Notes played on the organ will sustain for as long
as the key or pedal is depressed. There is no
sustain after the release of a note.

• Although they are not idiomatic for the
instrument, hand position skips and arpeggios

are possible when carefully scored or for special
effect.

• The dynamic contour throughout the range of
the pipe organ is static except through the
addition and subtraction of stops or the use of
the swell box and the crescendo. These devices
allow subtle accents, crescendos and
diminuendos not inherently possible on
the organ.