MIL-DTL-24223/4B(SH)
Degree of enclosure: Except for the opening required for acoustic radiation, the enclosure shall conform with
the totally enclosed requirements of MIL-STD-108. The opening for acoustic radiation shall be covered with mesh
or perforated metal not less than 0.032 inch thick. Mesh openings or perforations shall not be larger than 5/64 inch.
Where required for servicing internal assemblies, the mesh shall be removable.
Enclosure construction: Wire connections shall be closed lugs on a threaded terminal. For unsheltered, topside,
shipboard application. The enclosure shall contain required driver(s) and terminal board (if required); the
transformer enclosure shall contain the transformer assemblies and terminal board (if required). The enclosure shall
be provided with a removable cover (or horn assembly) to give access to all interior parts and the enclosure
mounting holes. The enclosure horn shall be secured by means of screws engaging in tapped holes provided in the
enclosure. Removing the cover shall not involve disturbance of incoming cables and terminal tubes. Part mounting
fasteners shall be secured so as not to require demounting of the enclosure for part replacement. Parts shall be
mounted so that their terminal markings are visible with the enclosure cover removed.
Coatings: Aluminum and aluminum alloy parts shall be pretreated and painted. The pretreatment shall be
either anodized in accordance with MIL-A-8625, or chemically pretreated in accordance with MIL-DTL-5541. It
shall then be primed with a single coat of a material conforming to TT-P-645 and a single top coat of enamel
conforming to MIL-DTL-15090 class 2, or coated with a polyester powder (equivalent to the weather and corrosion
resistance of polyester triglycidyl isocyanurate (TGIC)) rated for use in marine environments, designed to last longer
than the active loudspeaker element. The color shall be haze gray, color No. 26270, in accordance with Fed. Std.
595C.
Cable entrance: Entrance shall be as shown on FIGURE 1. The cable entrance hole shall accommodate a
stuffing tube, size 2, of ASTM F1836M, which shall accommodate one cable of type DSGA-4 of MIL-DTL-
24643/15.
Transformer and terminal block: The transformer and terminal block shall be enclosed in a watertight
enclosure.
Rotational base: Loudspeaker shall be designed for mast or deck mounting. The loudspeaker shall have a
rotatable base, enabling the sound to be transmitted in any direction in the horizontal plane.
Speaker drivers: The loudspeaker shall not exceed 16 driver units.
PERFORMANCE REQUIREMENTS:
Power input: Volt-ampere input specified in TABLE I shall provide at least sound pressure output, indicated in
TABLE I.
Sound pressure output: Sound pressure output shall be measured at the distance identified in TABLE I.
TABLE I. On-axis sound pressure output.
Decibel (dB) 1/ Output in Warble Band (Hertz)
Type
Distance
800 to
1,250 to
2,000 to
3,200 to
250 VA
(FT)
320 to 500
500 to 800
1,250
2,000
3,200
5,000
LS-397()/SIC
30
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108
113
114
114
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NOTE:
1/
dB re 0.0002 dynes/cm2 at the distance specified.
Sound pressure distribution:
2