Jbl 2447 h brochure

Page 2

F 2447H/J Compression Driver

High temperature voice coil former materials and adhee
sives enable the 2447H/J to handle high power levels over
extended periods of time The voice coils themselves are
identical to previous JBL models, so that impedance and
network matching will be the same After manufacture, the
frequency response of each transducer is tested for confore
mity to JBLs rigid performance standards

The model 2447H/J is ruggedly constructed to withstand
the rigors of both fixed installations and touring applicae
tions. All tolerances are held to the same high levels tradie
tionally associated with JBL designs The JBL manufacturing
process permits the use of rim centered diaphragms for
instant interchangeability and ease of field service

Architectural Specifications:

The compression driver shall consist of a ferrite magnetic structure
With all magnetic assembly parts machined from cast or extruded
billet stock. The phasing plug shall be assembled of concentric horns
to minimize phase cancellations. The diaphragm shall be .05 mm
(.002 in) pure titanium pneumatically drawn to shape and embossed
with radial reinforcing ribs to increase stiffness. High frequency
response shall be controlled through the use of a three dimensional
suspension structure. The voice coil shall be edgewound aluminum
ribbon of not less than 100 mm (4 in) diameter, operating in a
magnetic field of not less than 1.85 T (18,500 gauss).

Performance specifications of a rypical production unit shall be as
follows: Measured sensitivity with a 1 mW input on a 25 mm (1 in)
terminated tube, averaged from 500 Hz to 5 kHz, shall be at least 118
dB SPL. Measured sensitivity with a 1 \W input at 1 m distance onraxis
from the mouth of a horn with a Q of (1.3 averaged in the 2 kHz octave
band shall he at least 111 dB SPL. As an indication of electromechanical
conversion efficiency, the B1 factor shall be at least 18 Tesla meters.
Frequency response, measured on a terminated tube, shall be flat
within i 1 dB from 500 Hz to 3.3 kHz, with (i dB/octave rollsoff
above that point. Nominal impedance shall be 8 [16] ohms and power
capacity shall be at least 100 watts normal speech or music program
material.

The compression driver shall be the _]BL Model 2447HU]. ()ther
drivers will be considered for equivalency provided that submitted
data from a recognized independent test laboratory verify that the
above performance specifications are met.

Response on JBL 2352 BisRadiali'l-lorn

12a

.4
n
n
91
s
8
E
o
g
a
S
E
00 2% 500 1000 2000 5W0 IDODO 2m
mewyinflx
Frequency reponse of the 244m coupled to a jBL 2352 BirRadial
Horn, measured Onraxis at a distance of 1 meter with a 1 watt
(2.83 V RATS) input in a reflection free environment, with impedance
vs. frequency curve.
Response on PlaneeWave Terminated Tube
u my.
50 in
I "0 1w
3
g E
3 1 31.5 s
1: .
- E
3 i
m to E
. .. . .. 1
1 won 100" m
Winn:

Frequency response and impedance modulus of model 244m coupled
to a 38 mm ( /2 in) diameter terminated plane wave tube. This is the
power response of the transducer, and is the frequency response that
will be obtained on a true full range constant directivity horn design,
such as JBLs 2350 series of BisRadialhorns.

UBL

JBL Professional
8500 Balboa Boulevard, PO. Box 2200
Northridge, California 91329 UlSlAl

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