Allen Organ Company LLC MDS-26 User manual

MDS-26
Copyright © 1996 Allen Organ Company
All Rights Reserved
AOC P/N 033-0069

i
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.
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. The sections on
stop description and organ registration are intended for immediate use as well as for
future reference

ii
CAUTION
Do not plug the instrument into any current source other than 105-128 volts,
50/60 Hertz alternating current (AC). A verified grounded outlet is essential to
proper operation and protection of the instrument. Proper polarity should be
checked with an AC circuit analyzer before connecting the organ.
Do not change the cable plug or remove the ground pin or connect with a two-
pole adapter.
If you are in doubt about your electrical connection, consult your local electrician
or power company.
In churches where circuit breakers are turned off between worship services, the
circuit breaker affecting the organ console AC power should have a guard
installed to prevent its being accidentally switched off.
Read and comply with all instructions and labels that may be attached to the
instrument.
Warning: This equipment generates, uses, and can radiate radio frequency energy
and, if not installed and used in accordance with the instruction manual, may
cause interference to radio communications. It has been type tested and found to
comply with the limits for a Class B Computing Device in accordance with the
specifications in Subpart J of Part 15 of FCC Rules, which are designed to
provide reasonable protection against such interference in a residential
installation. Should this equipment cause interference to radio communications,
the user at his own expense will be required to take whatever measures may be
necessary to correct the interference. Whether this equipment actually causes the
interference to radio communications can be determined by turning the equipment
off and on. The user is encouraged to attempt to correct the interference by one or
more of the following measures:
Reorient the receiving antenna.
Relocate the organ with respect to the receiver.
Move the organ away from the receiver.
Plug the organ into a different electrical outlet, so that the organ and receiver are
on different branch circuits.
If necessary, the user should consult the dealer or an experienced radio technician
for additional suggestions.

iii
Contents
I. Description of Stops....................................................................................... 1
II. Solo Voices and Second Voices .................................................................... 8
III. Artistic Registration ....................................................................................... 9
IV. Transposer....................................................................................................13
V. Installation, Voicing, and Care of the Organ ...............................................14

1
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 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.
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.

2
Flute Voices
Open:
Harmonic Flute
Melodia
flute mutation stops
Stopped:
Gedackt
Bourdon
Quintadena
Rohrflöte
Voices of lesser harmonic development than Principal. Open
flutes somewhat imitative; stopped flutes 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:
Reed Voices
Chorus or Ensemble:
Trumpet
Posaune
Clairon
Solo:
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.

3
MDS-26 STOPLIST
Following is a discussion of individual stops and how they are generally used. Please
note that slight variations in specifications may be encountered.
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 defintion to a full pedal
combination, or as a solo Pedal trumpet.
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. (Optional board must be
added to implement MIDI.)

4
SWELL ORGAN:
Lieblichgedackt 16’ Softer stopped flute voice of delicacy and definition. Useful
where soft 16’ pitch is required.
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 8’ Soft string tone.
Viola Celeste 8’ String tone, slightly detuned, used with the Viola 8’ to create a
warm string celeste.
Celestes are created by using two sounds, one tuned slightly
sharp or flat of the other, creating a warm, undulating, “celestial”
effect. The combination of the Viola 8’ and Viola Celeste 8’
will create beautiful celeste sounds.
Spitzprinzipal 4’ Hybrid stop which is predominantly principal tone with a string
like 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.
Mixture 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 IV should
never be used without stops of lower pitches. The Mixture IV is
typically added to diapason or flute ensembles, or to a reed
chorus.

5
Basson 16’ Chorus reed tone at the 16’ pitch level, designed to supplement
the other chorus reeds. Also usable as a distinctive solo reed.
Trompette 8’ Chorus reed stop of rich harmonic develpoment. 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 Swell reed chorus. Particularly useful
as a solo voice.
Tremulant 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.
MIDI on Swell Opens MIDI channel to the Swell
Solo Organ Voices See separate section on Second Voices.
SWELL PERCUSSION VOICES
Celesta Delicate percussion sound similiar to a music box.
Harp Typical hand-plucked stringed Harp.
Handbells Typical English handbell sound.
GREAT ORGAN:
Diapason 8’ Foundation stop of the Great principal chorus, which consists of
the Diapason 8’, Octave 4’, and Superoctave 2’.
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.
Octave 4’ The 4’ member of the Great principal chorus.
Spitzflöte 4’ Partially stopped flute tone.

6
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.
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.
Swell to Great Intermanual coupler connecting all Swell stops to the Great
manual.
MIDI on Great Opens MIDI channel to Great.
Classic Voicing Gt-Pd See separate section on Second Voicing.
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 Swell stop, such as Trompette or
Basson, 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 I.B.
of the Console Controller™ Guide in this manual for more
information about alternate tunings.

7
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 Organ Off Used to switch off the Main Speakers.
Antiphonal Organ On This control switches on the Antiphonal speakers.
EXPRESSION PEDALS
The MDS-26 features three expression pedals. The pedal on the left expresses the Great
and Pedal divisions, while the center expression pedal affects the Swell. The one on the
far right is the Crescendo Pedal.
CRESCENDO PEDAL
One master Crescendo, for all divisions, gradually adds stops as this pedal is opened.
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 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.
RECALL PISTON
The “R” Piston, when activated, will recall the last combination set prior to using any
general or divisional piston.

8
SOLO VOICES AND SECOND VOICES
SOLO ORGAN VOICES
In addition to the comprehensive stop specification of the MDS-26, there are a variety of
solo stops that can be accessed from the Swell manual using the Solo Organ Voices.
These second voices are accessed from stop tablets in the Swell division. The stopnames
are printed on the stop tablets in red superscript as follows: Tuba Mirabilis, Open Flute,
Clarinet, and Cor Anglais. The Solo Organ Voices are activated by first depressing the
Solo Organ Voices stop tablet and then selecting the desired stop in the Swell division.
SWELL
Tuba Mirabilis 8’ An unusually brass-like and intensely loud Tuba. A brilliant
fanfare stop.
Open Flute 8’ an open wood or metal Flute of 8’ manual pitch.
Clarinet 8’ An imitative reed stop of 8’ pitch.
Cor Anglais 8’ An imitative reed stop of 8’ pitch sounding like its orchestral
counterpart.
CLASSIC SECOND VOICES
The characteristics of several stops in the Great and Pedal divisions can be changed using
the Classical Voicing Gt-Pd control. As in the Swell division, the second voices in the
Great and Pedal divisions are accessed from stop tablets. Certain stop tablets in the Great
and Pedal have two stopnames, one engraved in black, the other in red. Standard
specification stops are shown in black; Classic Second Voices are shown in red. Classical
Second Voices are accessed by first depressing the Classical Voicing Gt-Pd stop tablet
and then selecting the desired stops in the Great and Pedal divisions.
GREAT
Principal 8’ Foundation stop of 8’ pitch.
Holzgedackt 8’ A stopped wooden Flute of 8’ pitch.
Harmonic Flute 4’ A 4’ Flute of metal or wood construction.
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 with out
stops of lower pitches. It is typically added to Diapason or
Flute ensembles after the Mixture IV.
Carillon Suggests the sounding of small bells.
PEDAL
Sub Bass 16’ Principal stopped Bass of the organ.
Oktav 8’ Foundation stop of Diapason tone quality.

9
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 stops must 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 since the solo and accompaniment are under separate
expression.

10
SUGGESTED SOLO REGISTRATIONS
CHIMES SOLO
Swell: Viola 8’, Viola Celeste 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’
Great: Rohrflöte 8’, or Flute Celeste II (8’)
Pedal: Lieblichgedackt 16’, Gedacktflöte 8’
Play solo on Swell.
FLUTE SOLO
Swell: Gedackt 8’, or Solo Organ Voices, Open Flute (Koppelflöte 4’)
Great: Flute Celeste II (8’)
Pedal: Lieblichgedackt 16’
Play solo on Swell
TRUMPET SOLO
Swell: Trompette 8’, or Solo Organ Voices, Tuba Mirabilis (Gedackt 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.
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.

11
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 Section I.
The Swell Reed chorus of Basson 16’ and Trompette 8’ 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 top 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’, Superoctave 2’

12
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’, Sptizflöte 4’, Superoctave 2’, Mixture IV
Swell
1. Gedackt 8’, Viola 8’
2. Gedackt 8’, Viola 8’ Koppelflöte 4’
3. Gedackt 8’, Viola 8’ Koppelflöte 4’, Blockflöte 2’
4. Gedackt 8’, Viola 8’ Spitzprinzipal 4’, Koppelflöte 4’, Blockflöte 2’
5. Gedackt 8’, Viola 8’ Spitzprinzipal 4’, Koppelflöte 4’, Blockflöte 2’, Mixture IV
6. Gedackt 8’, Viola 8’ Spitzprinzipal 4’, Koppelflöte 4’, Blockflöte 2’, Mixture IV,
Trompette 8’
The use of the Swell to Great coupler allows these separate ensembles to be combined on
the Great manual. For example, the #5 Great and #3 Swell registrations coupled together
and played 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.
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.

13
TRANSPOSER
Vast computer capability 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 which is located underneath the left side of the console. Neutral (no
transposition) position for the knob is marked “z.” To shift the music to a higher key,
move the knob counter-clockwise. The key can be raised a maximum of five half-steps.
To shift to a lower key, move the Transposer knob clockwise from “z.” 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 “z” POSITION.
WHY TRANSPOSE?
1. Because the range of a song will not always suit the vocal range of a particular singer.
By adjusting the transposer, 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, and then
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. 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.

14
INSTALLATION, VOICING, AND CARE OF THE ORGAN
INSTALLATION
Wherever your MDS organ may be situated, careful installation is a prerequisite to
successful results. Your Allen representative is well qualified to guide you in planning
for this.
Factory assistance in planning the installation is also available and may, in fact, be sought
by your Allen Organ representative.
VOICING
The MDS organ enjoys unprecedented accuracy in the scaling and voicing of each note
of every stop. This musical breakthrough is an inherent part of the engineering design of
the instrument. Final adjustments in scaling and voicing involve controls within the
console and are best left to an expert. These adjustments are normally a part of
installation and, once done, should not require changes, unless the instrument is moved to
a new location.
Bass frequency projection is strongly affected by tone cabinet location. Although none
of the tone cabinets should be moved once the installation has been completed, extra care
should be exercised to prevent inadvertent movement of the bass tone cabinets.
REVERBERATION
The Digital Reverberation System provides the spatial ambiance of a large reverberant
auditorium. Although most effective in poor acoustic environments, it even enhances the
tones in optimal acoustic settings. The Digital Reverb is on all the time.
Adjustments to the Digital Reverberation System must be made by your service
technician or sales representative.

15
BATTERY BACKUP SYSTEM
The memory for the capture system on your MDS organ is sustained by a Lithium battery.
This allows capture settings and related items to be retained in memory when the organ is
switched off or unplugged. Under normal circumstances, the Lithium battery should last for
several years. A built-in warning system will alert you when the battery becomes weak and
needs to be replaced. The green power light will flash for about ten seconds after the organ is
switched on if the battery is in need of replacement.
Should the battery in your MDS organ require replacement, contact your local Allen
authorized service representative.
CARE OF THE ORGAN
Your Allen Digital Computer Organ constitutes a major advance in long-term
maintenance-free operation. There are no regular maintenance procedures required and,
therefore, no periodic maintenance schedules to be observed.
Reasonable care will keep the instrument looking beautiful for years to come. The wood
surfaces may be cleaned using a soft cloth dampened with lukewarm water. A mild
solution of lukewarm water and dish detergent may be used to remove fingerprints, etc.
Polish dry with a soft cloth.
Do not use wax, sprays or oils on the finish. Satin finished surfaces will take on a semi-
gloss appearance when waxed and will eventually become yellowed.
Keys and stop tablets should be cleaned in the following manner: Use two clean cloths.
Immerse one in clear, lukewarm water and wring it thoroughly damp dry. Loosen the dirt
with this cloth, then polish immediately with the dry cloth. Do not use soap or detergent
on keys or stop tablets.
You have purchased a remarkable organ that not only faithfully reproduces the organ
traditions of the past but also anticipates the innovations of the future. Should you have
questions that are not addressed in this manual, please do not hesitate to contact your
local Allen Organ representative. Welcome to the family of satisfied Allen Organ
owners!