Allen Organ Company LLC MDS-30 LDS User manual

LDS
MDS-30
Copyright © 1994 Allen Organ Company
All Rights Reserved
AOC P/N 033-0083

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ALLEN ORGAN COMPANY
For more than fifty years--practically the entire history of electronic organs--the
Allen Organ Company has sought to build the finest organs that technology would
allow.
In 1939, Allen built and marketed the world’s first purely electronic oscillator
organ. The tone generators for this first instrument used two hundred forty-four
vacuum tubes, contained about five thousand components, and weighed nearly
three hundred pounds. Even with all this equipment, the specification included
relatively few stops.
By 1959, Allen had replaced vacuum tubes in the oscillator organs with transistors.
Thousands of transistorized instruments were built, including some of the largest,
most sophisticated oscillator organs.
Only a radical technological breakthrough could improve upon the fine
performance of Allen’s solid-state oscillator organs. Such a breakthrough came in
conjunction with the U.S. Space Program in the form of highly advanced digital
microcircuits.
Your MDS organ is the product of years of refinement in digital techniques by
Allen engineers. It represents the apex of computer technology applied to exacting
musical tasks. The result is an instrument of remarkably advanced tone quality and
performance.

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Congratulations on the purchase of your new Allen Digital Computer Organ!
You have acquired the most advanced electronic organ ever built, one that
harnesses a modern computer to create and control beautiful organ tones.
Familiarize yourself with the instrument by reading through this booklet. We call
your attention particularly to sections on Transposer, Console Controller™,
Second Voicing, and MIDI Guide, since these elements are important to realizing
the full potential of the instrument.
The sections on stop description and organ registration are intended for immediate
use as well as for future reference. Because the Allen Digital Computer Organ
offers limitless tonal possibilities, plus authentic tone quality, these subjects can
now be more readily explored than ever before.

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Contents
I. Description of Stops.......................................................................................1
II. Artistic Registration.....................................................................................11
III. Transposer....................................................................................................16
IV. Capture Combination Action.......................................................................17
V. Installation, Voicing, and Care of the Organ...............................................18

MDS-30 LDS 1 Section I
DESCRIPTION OF STOPS
PITCH FOOTAGE
The number appearing on each stop along with its name indicates the “pitch” or
“register” of the particular stop. It is characteristic of the organ that notes of
different pitches may be sounded from a single playing key. When this sound
corresponds to the actual pitch of the playing key, the note (or stop) is referred to
as being of 8’ pitch; therefore, when an 8’ stop is selected and middle C is
depressed, the pitch heard will be middle C. If it sounds an octave higher, it is
called 4’ or octave pitch. If it sounds two octaves higher, it is called 2’ pitch, while
a stop sounding three octaves higher is at 1’ pitch. Likewise, a 16’ stop sounds an
octave lower, and a 32’ stop sounds two octaves lower.
Stops of 32’, 16’, 8’, 4’, 2’, and 1’ pitch all have octave relationships, that is, these
“even numbered” stops all sound octaves of whatever key is depressed. Pitches
other than octaves are also used in organ playing. Their footage number always
contains a fraction, and they are referred to as mutations. Among these are the
Nasard and Quinte 2-2/3’, Tierce 1-3/5’, and Quintflöte 1-1/3’. Because they
introduce unusual pitch relationships with respect to the fundamental (8’) tone,
they are most effective when combined with other stops, and are used either in solo
passages or in small ensembles of flutes (see explanation of Cornet in Section II).
TONAL FAMILIES
Organ tones divide into two main categories: flues and reeds. In a pipe organ, flue
pipes are those in which the sound is set in motion by wind striking directly on the
edge of the mouth of the pipe. Flues include principal tones, flute tones, and string
tones. Compound stops and hybrid stops are “variations” within these three
families.
The term “imitative” means that the organ stop imitates the sound of the
corresponding orchestral instrument; for example, an imitative “Viola 8’” would be
a stop voiced to sound like an orchestral viola.

MDS-30 LDS 2 Section I
Principal Voices
Principal
Diapason
Octave
Superoctave
Quinte
Characteristic organ tone, not imitative of orchestral
instruments. Usually present at many pitch levels, as well
as in all divisions. Rich, warm, and harmonically well
developed.
Flute Voices
Open Types:
Harmonic Flute
Melodia
Flute mutation stops
Stopped Types:
Gedackt
Bourdon
Quintadena
Rohrflöte
Voices of lesser harmonic development than principals.
Open types somewhat imitative; stopped types not.
Present at all pitch levels and in all divisions.
String Voices
Salicional
Viola
Voix Céleste
Mildly imitative voices of brighter harmonic development
than principal. Usually appear at 8’ pitch.
Compound Voices
Mixture
Cornet
Voices produced by more than one rank sounding
simultaneously.
Hybrid Voices
Gemshorn
Erzähler
Spitzflöte
Voices that combine the tonal characteristic of two
families of sound, e.g., flutes and principals, or strings and
principals.
In reed pipes, a metal tongue vibrates against an opening in the side of a metal tube
called a shallot. The characteristic sounds of different reeds are produced through
resonators of different shapes. The family of reeds subdivides as follows:

MDS-30 LDS 3 Section I
Reed Voices
Chorus or Ensemble types:
Trumpet
Posaune
Clairon
Solo types:
Hautbois
Clarinet
Krummhorn
Voices of great harmonic development; some imitative,
others not.
The Allen Digital Computer Organ provides authentic examples of various types of
voices as listed above. Some of these are protected by copyrights owned by the
Allen Organ Company. The voices are stored in memory devices, each having
affixed to it a copyright notice; e.g., © 1992 AOCO, © 1993 AOCO, etc., pursuant
to Title 17 of the United States Code, Section 101 et seq.
Following is a discussion of individual stops and how they are generally used.
Please note that slight variations in specifications may be encountered.

MDS-30 LDS 4 Section I
MDS-30 LDS STOPLIST
PEDAL ORGAN
Contre Violone 32’ Rich string tone at the bottom of the Pedal
division.
Diapason 16’ The 16’ member of the Pedal principal chorus.
Strongest pedal flue stop.
Bourdon 16’ Stopped flute tone of weight and solidity.
Lieblichgedackt 16’ Softer stopped flute of delicacy and definition.
(Swell expression) Useful where a soft 16’ pitch is required.
Octave 8’ 8’ member of the Pedal principal chorus.
Gedacktflöte 8’ Stopped flute tone of 8’ pitch, useful in adding
clarity to a pedal line in combination with the
Bourdon 16’ or Lieblichgedackt 16’.
Choralbass 4’ Pedal 4’ principal tone.
Mixture IV Compound stop of principal tones. One pedal
produces four distinct pitches at octave and fifth
relationships to the pedal being pressed. Used to
crown the Pedal principal chorus.
Posaune 16’
(Swell Expression) A strong Pedal reed that lends strength and “snarl” to the Pedal line.
Trompete 8’ Clear Pedal reed useful in adding definition to a
full Pedal combination, or as a solo Pedal trumpet.

MDS-30 LDS 5 Section I
SWELL ORGAN
Gedackt 8’ Stopped flute tone of moderate harmonic
development. Provides the 8’ member of the Swell
flute chorus and is useful by itself or with other
flutes and mutations in creating solo voices.
Viola Celeste II (8’) Two string tones, one slightly detuned from the
other, that create a warm string celeste.
Spitzprinzipal 4’ Hybrid stop which is predominantly principal tone
with a stringlike edge.
Koppelflöte 4’ Distinctive stopped flute voice that works well in
ensembles of flutes or strings, or as a solo voice.
Nasat 2-2/3’ Flute mutation that sounds one octave and a fifth
above the keys played. Always used with other
stops (usually beginning with 8’) for coloration.
Blockflöte 2’ A delicate, clear open flute at 2’ pitch.
Terz 1-3/5’ Flute mutation that causes the pitch to sound a
seventeenth (two octaves and a third) higher than
played. Used with 8’ stops or flute ensembles.
Fourniture IV Compound stop, or mixture comprised of principal
tones. Each note played produces four distinct
pitches at octave and fifth relationships to the key
being pressed. The mixture should never be used
without stops of lower pitches. The Fourniture IV
is typically added to diapason or flute ensembles,
or to a reed chorus.
Basson 16’ Chorus reed tone at the 16’ pitch level, designed to
supplement and undergird the other chorus reeds.
Also usable as a distinctive solo reed.

MDS-30 LDS 6 Section I
Trompette 8’ Chorus reed stop of rich harmonic development.
Can also be used as a solo voice.
Clairon 4’ A bright 4’ chorus reed. Combines with the
Basson 16’ and Trompette 8’ to form the full Swell
reed chorus. Also usable as a solo voice.
Tremulant (on rocker tablet) Use of this stop provides a vibrato effect, natural in
the human voice and wind instruments, when used
with the stops in the Swell division.
Swell Percussion Voices
(on rocker tablet) See separate scction on Second Voicing (page 13).
SWELL PERCUSSION VOICES
Celesta Delicate percussion sound similar to a music box
Harp Typical hand-plucked stringed Harp
Handbells Typical English handbell sound
GREAT ORGAN
Lieblichgedackt 16’ Softer stopped flute of delicacy and definition.
(Swell expression) Useful where a soft 16’ pitch is required.
Diapason 8’ Foundation stop of the Great principal chorus.
Rohrflöte 8’ Full-bodied, partially stopped flute tone.
Flute Celeste II (8’)
(Swell Expression) Two soft flute tones, one slightly detuned from the other to create a warm celeste.

MDS-30 LDS 7 Section I
Octave 4’ The 4’ member of the Great principal chorus,
which consists of the Diapason 8’, Octave 4’, and
Superoctave 2’.
Spitzflöte 4’ Partially stopped flute tone.
Superoctave 2’ An open metal stop that produces foundation tone
at the 2’ pitch level.
Waldflöte 2’ Open flute tone at 2’ pitch level.
Mixture IV A compound stop of principal tones. Four notes in
octave and fifth relationships sound together when
a single key is depressed. As pitches progress
upward, they “break” back to the next lower octave
or fifth. Used to cap the Great principal chorus,
adding brilliance and pitch definition throughout
the entire compass.
Cymbale III Compound stop of principal tones. One key
produces three distinct pitches at octave and fifth
relationships to the key being pressed. The
Cymbale III should never be used without stops of
lower pitches. It is typically added to Diapason or
Flute ensembles after the Mixture IV.
Krummhorn 8’
The tone quality of the shawm, a medieval ancestor of the clarinet, is the basis for this light,
bright, nasal reed. It can be used alone as a solo or
combined with light flues for a somewhat rounder
reed solo effect.
Chimes Typical Tubular Chimes.
Tremulant Same as Tremulant in Swell, but affects stops in
the Great and Pedal, except for the bottom octave
in both divisions.

MDS-30 LDS 8 Section I
COUPLERS
Great to Pedal Connects all Great stops to the Pedal.
Swell to Pedal Connects all Swell stops to the Pedal.
MIDI on Pedal Opens MIDI channel to the Pedal.
Swell to Great Intermanual coupler connecting all Swell stops to
the Great manual.
MIDI on Great Opens MIDI channel to Great.
MIDI on Swell Opens MIDI channel to the Swell.
GENERALS
Bass Coupler When this coupler is used, the lowest note played
on the Great manual will automatically key the
appropriate Pedal note, playing those stops that
have been drawn in the Pedal division as well as
those in the Great division.
Melody Coupler When used with an appropriate solo stop, such as a
Swell reed or Solo Organ Voice, this feature will
automatically key the highest note played on the
Great, allowing accentuation of the melody.
Alternate Tuning On When activated, the organ’s tuning will change to
the alternate tuning selected from the Console
Controller™. See section II.A. of the Console
Controller™ and MIDI Guide in this manual for
more information about alternate tunings.

MDS-30 LDS 9 Section I
Tremulants Full When activated along with one or more of the
organ’s tremulants, this control causes the
tremulants to become much deeper in their
oscillation than normal classical tremulants.
Useful for Gospel music, etc. Also known as
“Vibrato.”
Reverb Engages reverberation system.
(Activated using toggle switch
in Console Controller™ drawer)
Main Off Used in conjunction with the Antiphonal Organ
On tablet. This control disables the Main speakers.
Antiphonal Organ On Causes the organ to speak from the Antiphonal
speakers. The organ will speak from both
Antiphonal and Main divisions unless the Main
Off is also added.
EXPRESSION PEDALS
There are three expression pedals on the MDS-30 LDS. The one on the far right is
the Crescendo pedal (see below). The pedal on the left expresses the Great and
Pedal divisions, while the center expression pedal affects the Swell.
CRESCENDO PEDAL
One Crescendo, for all divisions, gradually adds stops as the pedal is depressed.
Indicator lights show the relative position of the pedal. Crescendo B is a secondary
Crescendo that can be programmed by the organist. Indiscriminate use of the
Crescendo pedal, in lieu of careful registration, should be avoided.
TUTTI I & II
The Tutti I and II are settings of full organ registration. Tutti II is a fuller
registration than Tutti I, most noticeably in the Pedal division. The Tuttis are

MDS-30 LDS 10 Section I
turned on by using manual pistons located beneath the Swell manual directly above
the Cancel button. The pistons are reversible, meaning that pressing them will turn
the corresponding Tutti on or off. The Cancel button will also turn off the Tuttis.
Pressing Tutti II will cancel Tutti I. Red signal lights, appropriately labeled and
located on the right side of the console to the left of the expression indicators, turn
on when Tutti I or II is in operation. A second set of Tuttis can be programmed by
the organist. Like the Crescendo, indiscriminate use of these devices should be
avoided.
SECOND VOICING
In addition to the comprehensive stop specification of the MDS-30-LDS, there are
a variety of percussion stops that can be accessed from the Swell manual using the
Swell Percussion Voices. The second voices are accessed from drawknobs in the
Swell division. The stopnames are printed on the drawknobs in red superscript as
follows: Handbells, Harp, and Celesta. The Swell Percussion Voices are activated
by first moving the Swell Percussion Voices rocker tablet to the “on” position, and
then drawing the desired stop in the Swell division.
CELESTES
Celestes are created by using two sounds, one tuned slightly sharp or flat of the
other, creating a warm, undulating, “celestial” effect. Drawing the Viola Celeste II
(8’) in the Swell Division or the Flute Celeste II (8’) in the Great division will both
create beautiful celeste sounds.

MDS-30 LDS 11 Section II
ARTISTIC REGISTRATION
Organ registrations fall into two broad categories: solo combinations and ensembles.
A solo combination is one in which a melody is played on one keyboard, the
accompaniment on another keyboard, and the pedal often provides a light bass line.
Almost any stop or combination of stops will sound good as a solo voice. A contrasting
tone quality should be chosen for the accompaniment, so that the accompaniment is
softer than the solo voice. The Pedal needs to provide a foundation for the sound without
covering it.
Most 8’ reed stops make interesting solo voices. The addition of a 4’ flute or a flute
mutation (e.g., Nasat or Terz) to a reed such as the Trompette colors the sound further
and increases its volume slightly. Adding an 8’ flute to a reed will add body to the
sound.
Flutes can be used alone or in combinations as solo voices. One special combination of
flutes that creates an appealing and historically significant solo combination is the Cornet
(pronounced kor-NAY). The Cornet is created by using the following Swell stops:
Gedackt 8’, Koppelflöte 4’, Nasat 2-2/3’, Blockflöte 2’, and Terz 1-3/5’. This solo
combination was used widely in Baroque organ music, but it is just as appropriate for
some modern music. Useful variations of the Cornet may be achieved by eliminating the
4’, the 2’, or both.
When choosing stops for a solo voice, it is not always necessary to include an 8’ stop; for
example, since the 4’ flute has a tone quality different from that of the 8’ flute, the 4’
flute can be used as an independent solo voice. By playing the solo an octave lower than
written, the notes will sound at the correct pitch. In similar fashion, a 16’ stop can be
selected and the notes played an octave higher than written. Tonal variety will be gained,
because each stop has its own tone color.
For accompaniment, the most desirable voices are the 8’ flutes or strings on each manual.
Celestes often make effective accompaniments. The correct choice depends on the
volume of the solo tone (a soft solo voice requires the softest accompanimental stop), the
element of contrast, and the location of the solo stop. A bright, harmonically rich solo
reed, for example, can be accompanied by either a string or flute, but the flute will often
contribute greater interest because of its greater contrast.
Try to seek a “natural” balance of volume between solo and accompaniment. This will
be especially easy to accomplish if the solo and accompaniment are under separate
expression.

MDS-30 LDS 12 Section II
SUGGESTED SOLO REGISTRATIONS
CHIMES SOLO
Swell: Viola Celeste II (8’)
Great: Chimes
Pedal: Lieblichgedackt 16’, Swell to Pedal
Play solo on Great.
SWELL SOLO COMBINATION
Swell: Gedackt 8’, Koppelflöte 4’, Nasat 2-2/3’, Blockflöte 2’, Terz 1-3/5’ (Tremulant
optional)
Great: Rohrflöte 8’; alternatively, Flute Celeste II (8’)
Pedal: Lieblichgedackt 16’, Gedacktflöte 8’
Play solo on Swell.
FLUTE SOLO
Swell: Gedackt 8’
Great: Flute Celeste II (8’)
Pedal: Lieblichgedackt 16’
Play solo on Swell.
TRUMPET SOLO
Swell: Trompette 8’
Great: Diapason 8’, Octave 4’, Superoctave 2’, Mixture IV, Classic Voicing Gt-Pd
Pedal: Diapason 16’, Octave 8’, Choralbass 4’, Mixture IV
Play solo on Swell.
These few combinations demonstrate basic techniques of solo registration. In
creating registrations of your own, remember these three simple rules:
1. Seek tonal contrast between solo and accompaniment.
2. Be sure the solo is louder than the accompaniment.
3. Choose a solo whose character is appropriate to the specific piece.

MDS-30 LDS 13 Section II
ENSEMBLE REGISTRATIONS
Ensemble registrations involve groups of stops that are played together, usually, but not
always, with both hands on one keyboard. They are characterized by compatibility of
tone, clarity, and occasionally power. Such registrations are used in hymn singing, choir
accompaniments, and much of the contrapuntal organ literature.
Volumes have been written on the subject of ensemble registration. Following is a
summary of the major points.
Ensembles are created by combining stops. Two factors are always to be considered:
tone quality and pitch. Ensembles begin with a few stops at the 8’ and/or 4’ pitch and
expand “outward” in pitch as they build up. New pitches are usually added in preference
to another 8’ stop.
Ensembles are generally divided into three tonal groupings or “choruses”:
The principal chorus is the most fully developed with
representation in various divisions of the organ and at every
pitch from 16’ (Diapason) to high mixtures. The principal
chorus is sometimes called the narrow-scale flue chorus, a
reference to the relative thinness of principal pipes in relation
to their length.
The flute chorus is also well represented with a diversity of
stops at various pitches. Generally speaking, the flute chorus
is composed of less harmonically developed tones, and is
smoother and of lesser volume than the principal chorus. The
flute chorus is sometimes called the wide-scale flue chorus,
owing to the generally “fatter” look of flute pipes as
compared to principals.
The reed chorus includes those reed tones designed to be used
in the ensemble buildup. Not all reed voices are ensemble
tones. An Hautbois, for example, is usually a solo stop. The
various Trumpets, Clairons, Bassons, etc., are usually
ensemble voices that add brilliance, power, and incisiveness
to the sound. If you have questions as to whether a specific
reed is a solo or ensemble stop, refer to the stoplist in the
preceding section.

MDS-30 LDS 14 Section II
The Swell reed chorus of Basson 16’, Trompette 8’, and Clairon 4’ represents an entity
important to French organ music and the full ensemble of the organ. These stops create a
“blaze” of richly harmonic sounds that tops off both flue choruses.
Another special ensemble combination important in French music is the Cornet, which
was discussed in the section on Solo Registration. This combination can be used with the
chorus reeds and mutations to create the “Grand Jeu.” The Cornet is also useful in
Romantic ensembles to add weight and thickness to the sound.
Here are typical ensemble combinations for the Swell and Great manuals:
Great
1. Rohrflöte 8’, Spitzflöte 4’
2. Rohrflöte 8’, Spitzflöte 4’, Waldflöte 2’
3. Diapason 8’, Octave 4’
4. Diapason 8’, Octave 4’, Superoctave 2’
5. Diapason 8’, Octave 4’, Superoctave 2’, Mixture IV
6. Diapason 8’, Rohrflöte 8’, Octave 4’, Spitzflöte 4’, Superoctave 2’, Waldflöte 2, Mixture IV
Swell
1. Gedackt 8’, Flute Celeste II (8’)
2. Gedackt 8’, Koppelflöte 4’
3. Gedackt 8’, Koppelflöte 4’, Blockflöte 2’
4. Gedackt 8’, Spitzprinzipal 4’, Koppelflöte 4’, Blockflöte 2’
5. Gedackt 8’, Spitzprinzipal 4’, Koppelflöte 4’, Blockflöte 2’, Fourniture IV
6. Gedackt 8’, Spitzprinzipal 4’, Koppelflöte 4’, Blockflöte 2’, Fourniture IV, Trompette 8’
The use of the Swell to Great coupler allows these separate ensembles to be combined on
the Great manual. It is also possible to combine some of these ensembles within the
same division; for example, the #2 and #4 registrations suggested above for use on the
Great combine to form a nice round hymn combination.
The Pedal ensemble is created in much the same way as the manual ensembles, starting at
16’ pitch instead of 8’. Be careful that the volume of the pedals is not greater than that of
the manuals. Although the manual to pedal couplers are useful in bringing clarity to the
pedal line, especially on softer registrations, avoid the temptation to rely constantly on
one or two 16’ stops and a coupler. Please note that the softest stops and flute mutations
are normally not used with ensembles.

MDS-30 LDS 15 Section II
FULL ORGAN
Due to the immense capabilities of the Allen Digital Computer Organ, every stop
and coupler on the instrument could be used simultaneously without distortion, if
the organ is adjusted properly. In good registration practice, however, the organist
would not haphazardly put on every stop on the instrument. For best results, listen
and include only those stops that really contribute to the fullness and brilliance of
the ensemble. Eliminate soft stops and solo stops that make no purposeful
contribution.
This short treatment barely scratches the surface of the fascinating subject of organ
registration. For those interested in gaining further insight into this vital area of
organ playing, we recommend the following texts:
Audsley, George Ashdown. Organ Stops and their Artistic Registration.
Hialeah, FL: C.P.P. Belwin, 1985.
Irwin, Stevens. Dictionary of Pipe Organ Stops. 2nd ed.
New York: Macmillan Books, 1983.

MDS-30 LDS 16 Section III
TRANSPOSER
The vast capability of the computer makes it possible to perform the sometimes
difficult task of transposing while allowing the organist to play in the notated key.
Operation of the Transposer is controlled by the Transposer knob, found inside the
Console Controller™ drawer. Neutral (no transposition) position for the knob is
marked “N.” To shift the music to a higher key, move the knob counter-clockwise
one or more half-steps. The key can be raised a maximum of five half-steps, in
half-step increments. To shift to a lower key, move the Transposer knob clockwise
from “N.” The key can be lowered a total of seven half-steps.
A RED INDICATOR LIGHT COMES ON WHENEVER THE TRANSPOSER
KNOB IS MOVED FROM THE “N” POSITION.
WHY TRANSPOSE?
Because the range of a given song will not always suit the vocal range of a
particular singer. By adjusting the key upward or downward, whichever is
appropriate, the piece can be sung more comfortably and effectively.
2. Because some instruments are non-concert pitch. A trumpet in Bb, for example,
can play the same music as the organist, if the Transposer knob is set two
half-steps lower.
3. Because hymn singing can sometimes be improved by a more favorable key
selection. Hymn singing can also be enhanced by playing the hymn in its original
key, playing a short modulation at the end of the stanza that leads into the key
one-half step above the key in which the hymn is written, then turning the
Transposer up a half-step for the next stanza. In this way, the organist can play the
next stanza in its original key, and it will sound one-half step higher. If the hymn
is already in a fairly high key, it may be preferable to play the first few stanzas
with the Transposer set down one-half or one whole step, then modulate up to the
original key for the final stanza. The use of modulation with the aid of the
Transposer can create a climactic effect for the final stanza of a hymn.