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b, 2405H Ultra-High Frequency Transducer
better temperature stability, resistance to demagnetiza-
tion, reduction in weight over typical ferrite material, and
give the highest performance on an actual production
basis. By precise machining, a flux density of 1.75 tesla
(17,500 gauss) in the voice coil gap is realized.
The diffraction horn assembly is die cast of solid
aluminum. Internally, the annular voice coil diaphragm is
pneumatically formed of fatigue-resistant aluminum alloy.
Wire used in the 44 mm
(13/4 in) voice coil is aluminum,
milled to a thin ribbon. This process places a maximum
amount of conductor in the magnetic gap for optimum
efficiency and transient response.
The use of high-temperature voice-coil former materials
and adhesives has improved the power handling and rug-
gedness of the driver. The voice coil itself is identical to
the previous alnico magnet model, so that impedance and
network matching will be the same.
Architectural Specifications:
The transducer shall have a maximum diameter of 98 mm (3/8 m)
and a depth of 83 mm (3% in) and weigh not less than 2.3 kg (5 lb).
The dlffraction horn shall be die cast of aluminum and the magnetic
circuit will weigh not less than 1 8 kg (4 lb ).
Voice co11 diameter shall be 44 mm (1% in), operatmg m a magnetic
field whose flux density measures at least 1.75 T (17,500 gauss). Voice
coil wire shall be milled alummum ribbon
The transducer shall have a measured sensltlvity (SPL at 1 m (3.3 ft)
with a 1 W input, swept from 7 kHz to 20 kHz) of at least 105 dB on
axls On-axls frequency response measured under free field condo-
tions at a distance of 18 meters (6 ft) or more shall extend from 7 kHz
to 20 kHz within plus or minus 3 dB. Horizontal dispersion shall be
uniform at 45 degrees off-axls at 16 kHz and 30 degrees off-axis at 20
kHz, when measured at the 6 dB down pomts relative to on-axls fre-
quency response characteristics using %-octave band pink noise as the
slgnal source
Nominal Impedance shall be 8 ohms and power capactty shall be at
least 20 watts when driven by pink noise, band-limited from 6 kHz to
20 kHz.
The transducer shall be JBL Model 2405H
r
200
180
100 8: 70 60
SO
40
30
/ I , I
20 I
I
I I I
I I
Beamwidth vs. Frequency
10 I
2 3 5
10 20
Frequency, kHz
Vertical dispersion of the 2405H.
T
I
j__-
-l-L
Polar response of the 2405H in the horizontal plane,
measured with %-octave band pink noise in a free-field
environment.
JBL Professional
8500 Balboa Boulevard, PO. Box 2200
Northridge, California 91329 U.S.A.
H A Harman International Company W9110M
P1058
