Hammond Model A, Manual, Page: 56 / 298

ACOUSTICS
THE PART THEY PLAY IN HAMMOND ORGAN INSTALLATIONS
INSTALLATIONS IN GENERAL:
The proper installation of a Hammond organ requires the careful observance of
four primary rules:
1. The organ should furnish AMPLE POWER.
2. The sound energy from the organ should be EVENLY DISTRIBUTED.
3. The console and tone cabinets should be so located in relation to each other and
to the audience, choir, soloist, etc., that a PROPER TONAL BALANCE is
accomplished.
4. The organ tone should be PROPERLY REVERBERATED.
The observance of these rules with due consideration to the particular use for which
the instrument is required will insure the best possible installation in any type of
enclosure. These rules will be discussed in detail in the following pages.
POWER
There are so many factors which have a bearing on the amount of power or sound
energy necessary for best musical results in a given enclosure that an accurate
formula for determining the required power in all cases would be too cumbersome for
everyday use. Experience has shown that it is very seldom that too many tone
cabinets are specified. Therefore, if there is doubt as to the sufficiency of tone
cabinets for any installation it is reasonably safe to double this amount. This will
greatly improve the musical quality of the instrument and eliminate overloading of
the speakers. Some of the factors which have a bearing on the amount of tone cabinet
equipment required in any enclosure are the size and shape of the enclosure,
placement of tone cabinets, amount and location of sound-absorbing materials
including persons present in the enclosure. The use for which the organ is desired
also has a bearing on requirements; for example, an organ to be used primarily to
support congregational singing would require more tone cabinets than one that is to
be used mainly for accompaniment of soloists or light entertainment.
The following conditions in an enclosure, therefore, usually indicate that more than
an average installation may be required:
1. When the area of the boundaries of the enclosure is great in proportion to the
volume of the enclosure. Thus, an enclosure of irregular shape having numerous
alcoves, etc.,would require more tone cabinets than one of cubical shape.
2. When the tone cabinets are located in a position where considerable sound
absorption takes place before the music reaches the listener. A poorly designed or
constructed organ chamber is an example.
3. When acoustical correction materials are used on walls or ceiling, when heavy
drapes are present and carpets are used for floor covering.
4. When seating capacity is high for the size of the enclosure. For practical
purposes an open window is considered as an area of 100 percent absorption of sound.
A single person absorbs about as much sound as four square feet of open window.
Therefore, an audience of 1,000 people will have the effect on music volume of an
open window area of 4,000 square feet as compared with the volume heard when the
enclosure is empty. To offset this absorption, a disproportionately greater amount
of tone cabinet equipment must be used.
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