Jbl 2450 j brochure

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URL

2 4 5 0H0 Compression Driver

Professional Series

Key Features:

>100 watts continuous program
at 500 Hz

151) watts continuous program
at 1 kHz or higher

>Neodymium rarerearth magnet
structure provides high output, light
weight, and compact size

Coherent W'ave phasing plug design
for increased highrfrequency output

>100 mm (4 in) pure titanium
diaphragm with radialrrib topology
and patented threerdimensional diar
mond pattern suspension

100 mm (4 in) edgewound
aluminum Voice coil

>49 mm (2 in) throat exit diameter

The model 2450H/J is a professional
quality, compact size and light weight
largerformat compression driver that
incorporates a neodymium rarerearth
magnet assembly designed by extenr
sive computer modeling including
finite element analy The new magi
net assembly provides the equivalent
electromechanical conversion effir
ciency (B1 factor) at tworthirds
the size and onerthird the weight
required by previous largerformat
compression driver designsi

The newlyrdeveloped Coherent
\Wave phasing plug assembly consists
of four diercast annular aperture
structures of constant path length to
provide inrphase combining of diar
phragm output at the drivers exiti
This optimized configuration allows
coherent summation of energy up to
much higher frequencies than pre
vious designs, with an attendant in,
crease in perceived highrfrequency
clarity

The new diaphragm design includes
JBLs exclusive threerdimensional
diamond pattern surround which
reduces membrane stresses in the
diaphragm support structure and
extends diaphragm life The depth of
the diamond pattern is closely con,
trolled during the manufacturing
process to provide predictable free
quencies for the 2nd and 3rd normal
resonance modes and for the basic
suspension resonance modei

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Specifications:

Throat Diameter:

49 mm (2 in)

Nominal Impedance:

2450171 8 ohms
2450] 16 ohms

Minimum Impedance:
DC Resistance:

6 ohms (ii), 12 ohms (I) @5 kHz
4.3 ohms (H), 8.5 ohms (1) i 10% @ 25%

Power (:npneiry':

100 w continuous program above 500 Hz
150 \v continuous program above 1 kHz

Sensitiv y:

111 dB SPL, 1 \X' @ 1 m on s on horn2
118 dB SPL, 1 m\( on planerwmc tube3

Nominal Efficiency:

3 "/0 (500 Hz to 2.5 kHz)

Frcquency Range:

500 Hz to 20 kHz

Recommended Crossover:

500 Hz or higher, 12 dB/octave minimum

Diaphragm:

0.05 mm (0.002 in) pure drnnium

Voice Coil Diameter:

100 mm (4 in)

Voice Coil Material:

Edgcwound aluminum ribbon

Flux Density:

1.9 T (19000 gauss)

Bl Factor:

12.7 (H) N/A
18 (I) N/A

Positive voltage to black terminal gives

diaphragm motion toward the phasing plug

Dimensions: 167 mm (637/6! in) diameter
139 mm (5 29/64 in) depth
blounting: Four '/i,20 threaded holes, 90° apart on 101.6 mm

(4 in) diameter

Net Weight: 4.8 kg (10% lb)

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> 2450H/J Compression Driver

Highrtemperature voice coil former materials and adher
sives enable the 2450H/J to handle extremely 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 driver is
tested for conformity to JBLs rigid performance standards

The model 245(lH/j is ruggedly constructed to with
stand the rigors of fixed and transportable commercial
applications. All cast parts and tolerances are held to the
same levels traditionally associated with JBL designs.
Highrpressure pressrflt assemblies combined with pres
eisely machined interlocking parts assure extended resis
tance to mechanical shock The JBL manufacturing pro
cess also permits the use of rim centered rather than pin
mounted diaphragms, for instant interchangeability and
ease of field service.

Architectural Specifications:

The compression driver shall consist of a neodymium magnetic
structure with all magnetic assembly parts machined from east or
extruded billet stock. The phasing plug shall be assembled of cone
centric horns of equal path length to eliminate phase cancellations,
and it shali be coupled to a tapered throat. The diaphragm shall be
0.05 mm (0.002 in) pure titanium pneumatically drawn to shape and
embossed with radial reinforcing ribs to increase rigidity. High free
quency 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) in diameter, operate
ing in a magnetic field of not less than 1.9 tesla (19,000 gauss).

Performance specifications of a typical production unit shall be as
follows: Measured sensitivity with a 1 m\X input on a 25 mm (1 in) tcrr
minated tube, averaged from 500 Hz to 2.5 kHz, shall be at least 118
dB SPL. Measured sensitivity with a 1 \Y' input at 1 m distance on axis
from the mouth of a horn with a Q of 6.3 averaged in the 2 kHz octave
band shall be at least 111 dB SPL. As an indication of electromechanical
conversion efficiency, the B1 factor shall be at least 18 newtons per
ampere. Frequency response, measured on a terminated tube, shall
be flat within t 1 dB from 500 Hz to 3.3 kHz, with 6 dB / octave rolls
off 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 JBL Model 2450H/J. Other
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 2380A FlatrFront BirRadialK Horn

no mo
1:?
n.
3
N w
you 31.5 g
m a
B 3
d e
w i
so 10 s
so ' " 3.1
too looo moon zuooo

Frequency in N1

Frequency response or the 2450] coupled to a jBL 2380A FlatrFront Bi,
Radialllorn, measured onraxis at a distance of 1 meter with a lrwatt
(4.0 V RNIS) input in a reflectionrfrcc environment, with impedance
vs. frequency curve. A horn with a pure exponential flare, such as [)1in
cal radial horn designs, will exhibit greater high frequency output on
axis at the expense of lost annular coverage.

Response on PlanerWave Terminated Tube

m
150 125
«o no 100
E
e c,
8 m
g inc 1013 31.5 E
m 6
~e o
A E
e
"' §
120 90 w 5
ma

00 1000 tonne 20000
Frequency 1n Hz

Frequency response and impedance modulus of Model 2450} coupled
to a 49 mm (2 in) diameter terminated planerwavc tube, with Sen
sitivity referenced to a 25 mm (1 in) tube. This is the power response
of the transducer, and is the frequency response that will be obtained
on a true fullrrange constant directit' v horn design, such as JBLs
2360 series of Constant Coverage BirRadial' Horns.

Jul. tonnoually engages In research related to produtr uupnnrmrur NL auuenal., pro
duruon nit-thorn, and design refinements arr uuiotlutrtl into tumug protlutu uirhour
a meme u\p\c~slun or that phllosophl For this mason am more: lul. produtr
-r in some impetr horn in puhlohetl destnptlon but uill alaays equal or tart-rd

uoutr
uun tit

rlte original design .petiiitauous unless otheraise stated

UBL

JBL Professional
8500 Balboa Boulevard, PO. Box 2200
Northridge, California 91329 U.S.At :sRIEfiiIIn/l

H \ lliirmim luteuiauoual Company ill/"m