MIL-DTL-24223/2B(SH)
PHYSICAL REQUIREMENTS:
Description: Type LS-387()/SIC, LS-388()/SIC, LS-535()/SIC, and LS-536()/SIC loudspeakers shall be
designed for bulkhead mounting. Each loudspeaker enclosure shall contain a single drive unit and a line
transformer.
Dimensions and weight: See FIGURE 1.
Reflecting horn: A double reflecting horn is required (this is to protect the diaphragm and limit horn depth). If
a single assembly reentrant horn is used, a mechanical swage process shall be used to connect the spider to the
reentry horn. Removing the top horn enclosure shall not involve disturbance of internal wiring and/or components.
Drainage: External and internal water drainage shall be provided for mounting angles from straight down to
45 degrees above horizontal. The reflector horn shall have a drain hole.
Degree of enclosure: Except for the opening required for acoustic radiation, the enclosure shall conform with
the totally enclosed requirements of MIL-STD-108.
Enclosure construction: The enclosure shall contain required driver(s), terminal board, switch, and transformer
assemblies. 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 cover (or horn assembly) 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: The loudspeakers shall be designed to admit cable through the enclosure via two stuffing tubes.
The stuffing tubes and plug will be in accordance with size 2 of ASTM F1836M. One stuffing tube shall be
plugged. Stuffing tubes shall be supplied as a part of the enclosure.
Magnet structure: Magnet structures for loudspeaker units used in the LS-535()/SIC and LS-536()/SIC shall be
of special design to limit the amount of stray magnetic field surrounding the structure.
Special marking for LS-535()/SIC and LS-536()/SIC loudspeakers: An instruction plate shall be provided on
the front of these loudspeakers to indicate the correct mounting position to minimize stray magnetic field below the
loudspeaker. The instruction plate shall be in accordance with MIL-DTL-15024 Types A, B, F, or H; attachment
shall be by mounting screws.
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.
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