Horizontal 1/3 Octave Polars
Architectural Specifications:
The loudspeaker shall consist of a 200 mm (8 in) low frequency
transducer, 25 mm (1 in) high frequency transducer, and frequency
dividing network installed in a ported enclosure. The low frequency
voice coil shall be 32 mm (1-1/4 in) in diameter.
Performance specifications of a typical production unit shall be as
follows: Measured sensitivity (SPL at 1 m [3.3 ft] with 2.83V input,
averaged from 500 Hz to 1.5 kHz) shall be at least 92 dB-SPL. Usable
frequency response shall extend from 60 Hz to 16 kHz (10 dB below
rated sensitivity, in half-space, with no external equalization). Nominal
impedance shall be 8 ohms. The frequency dividing network shall have
a crossover frequency of 2.8 kHz. Rated power capacity shall be at least
175 watts continuous program power, defined as 3 dB above a test signal
of filtered random noise conforming to international standard IEC268-5
(shaped pink noise with a peak-to-average ratio of 6 dB), for 100
continuous hours duration.
The system shall be protected against damage from occassional
overpowering via full range series lamps that limits the power to the net-
work and transducers. The high frequency transducer shall be horn-
loaded to more evenly cover a nominal 90° horizontal by 90° vertical
area.
The enclosure shall be constructed of high-impact polystyrene for
protection against the elements in outdoor applications, and for
paintability. The grille shall be completely zinc-coated for resistance
against rusting, shall be bake-painted black, and shall be secured via
screws to keep it in place when facing downward.
The low frequency transducer shall have a polypropelene cone and a
butyl rubber surround which shall extend seamlessly over the edge of
the speaker frame for protection against the elements. The high
frequency transducer shall be constructed of polycarbonate, reinforced
with a titanium film for additional weather resistance. The system shall
withstand Mil Spec 810 testing with specified time durations for
exposure to the following environments with no effect on its acoustical
performance or structural integrity: salt spray (method 509.3),
temperature -19°C to 49°C (method 501.3 and 502.3), 95% humidity
(method 507.3) and ultra-violet (method 505.3). The system shall have a
IEC 529 splashproof rating of IP-34.
For theft deterrence, the installation access area shall be hidden
behind a snap-out cover, and the access area shall be on the front of the
loudspeaker for ease of installation and adjustment. The loudspeaker
shall be rotatable over a minimum of ±35° in all directions via a ball-
type mounting system. The ball mechanism shall be internal to the
cabinet to allow low-profile mounting and better stability via a short
moment arm. The logo shall be rotatable for proper orientation when
the loudspeaker is mounted horizontally or vertically.
The external wiring connectors shall be spring loaded and gold
plated, and shall accept bare wire, single or dual banana-type
connectors with 19 mm (3/4 in) spacing. Overall cabinet dimensions
shall be no greater than 380 mm (15.0 in) high by 280 mm (11.0 in)
wide by 220 mm (8.6 in) deep and shall weigh no more than 5.5 kg (12
lbs).
The finish shall be a paintable lighly textured black.
The system shall be the JBL Model Control 28 with included Invisiball
®
mounting system.
