Jbl 2490 h brochure

Page 1

zJBL

2490 mm$

Compression Driver

Professional Series

Key Features:

>200 watts continuous program
above 250 Hz

>Optimized phasing plug design
for low distortion, smooth
response, and wide bandwidth

>100 mm (4 in), .08 mm (.003 in)
thickness, titanium diaphragm

>76 mm (3 in) throat exit diameter

.100 mm (4 in) edgewound
voice coil

The Model 2490H is a unique addie
tion to JBLs family of professional
quality compression drivers. The
design goal was to provide very high
level sound pressure at low distortion
over the bandwidth of 250 Hz to
above 3 kHz Extensive computer
modeling, including finite element
analysis and boundary element
analysis, were used to optimize the
magnetic structure, phasing plug,
and diaphragm. This application of
advanced technology has produced a
smaller, lighter weight compression
driver with better performance than
previous highepower midrange
transducers.

A new phasing plug was developed
with an optimized two slit configura
tion A fiveetoeone compression ratio
produces very low distortion and
smooth, wide bandwidth responses

The new diaphragm design includes
JBLs exclusive threeedimensional diar
mond pattern surround tuned to
reduce fatigme inducing stresses in the
membrane and support structures

Precision engineering and manufac7
turing processes provide controlled
normal and suspension resonance
modes The diaphragm and suspen7
sion use 3 mil pure titanium for
high stiffness and freedom from
breakup modest

A long voice coil design using high
temperature voice coil former
material and adhesives enable the
2490 to handle high power levels
over extended periods of time

15 Palm" 44,324,312 1:0an pmm pending

Page 2

b 2490H Midrange Compression Driver

Architectural Specifications:

The compression driver shall consist of a ferrite magnetic structure
With all magnetic assemhly parts machined from cast or extruded
billet stock. The phasing plug shall be assembled of concentric horns
to minimize phase cancellations. The diaphragm shall he .08 mm
(.003 in) pure titanium pneumatically drawn to shape. 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 1.5 1' (15,000 gauss).

Performance specifications of a typical production unit shall be as
follows: Measured sensitivity with a 45 in\X7 input on a 76 mm (3 in)
plane wave tube, averaged from 300 Hz to 4 kHz, shall he at least 123
dB SPL. Measured sensitivity with a 1 \X' input at 1 m distance on axis
from the mouth of a horn with a Q of 20 averaged in the 2 kHz octave
band shall he at least 114 dB SPL. As an indication of electromechanir
cal conversion efficiency, the Bl factor shall he at least 18 Tesla meters.
Frequency response, measured on a terminated tube, shall be flat
within i 1 dB from 250 Hz to 2.5 kHz. Nominal impedance shall be 8
ohms and power capacity shall he at least 200 watts normal speech or
music program material.

The compression driver shall he the JBL Model 2490. Other drivers
will be considered for equivalency provided that suhmitted data from
a recognized independent test laboratory verify that the above perforr
mance specifictions are met

41 mm
(1.6 in)

223 mm
76 mm ( 8. 8 in)

V

" 15.2 mm
3/5 - 16 on _
6 inch (152 mm) (0.6 in) l
bolt circle, 4 places.
91.4 mm
(3.6 in)

Note: Dimensvon in ( l
are in inches.

Response on JBL 2393 BirRadialkHorn

20

10
E
a
8
g mot 31.6
Q s
a é
a -
so E
G
8.
g
60 . . 3.16
100 200 500 1000 2000 5000 10000

Frequency in Hz

Frequency response of the 2490ch coupled to a jBL 2393 BieRadial
Horn, measured onraxis at a distance of 1 meter with a lewatt

(2.83 V rms) input in a reflection free environment, with impedance
vs. frequency curve.

Response 0n PlanerW'aVe Terminated Tube

130

E

SPL. as (re 20 am)
3

or

E

g

Q.

100 §
- n

-a

K

.5

so - ~ .
1w zoo son 1000 2000 5000 10000

Frequency in Hz

Frequency response and impedance modulus of model 249nm
coupled to a 76 mm (3 in) diameter terminated plane wave tube
This is the power response of the transducer. (on v rms input).

UBL

JBL Professional

8500 Balboa Boulevard, PrO. Box 2201)
Northridge, California 91329 USA. /
10 94 19M

H .\ Harman international coinpani 1mm