JBL 2485-J Brochure

PROFESSIONAL SERIES

FEATURES:

120 watts continuous program above 300 Hz

100 mm (4 in) edgewound aluminum ribbon

voice coil

100 mm (4 in) phenolic diaphragm

49 mm (2 in) horn throat diameter

Model 2485J is an extremely high-power profes­sional-quality compression driver It has a 100 mm
(4 in) voice coil and a magnetic structure weighing

10.5 kg (23 lb). It can take the most explosive tran­sients in stride and reproduce them at thunderous
levels. Model 2485J is built to typical JBL standards
of precision.

Diaphragms of phenolic impregnated linen are

virtually indestructible. After manufacture, each

driver is tested for conformity to rigid performance
standards.

The driver features a waterproof rear cover for

the mounting of a line matching transformer in

outdoor applications. A waterproof gland nut allows
cable connections to be made while maintaining
moisture isolation integrity.

Model 2485J is unequalled by any other driver in
both power capacity and efficiency. It can be used
as the high frequency section of two-way systems
for high-power reinforcing applications or by itself
with a 300 Hz high-pass filter for voice paging or
reinforcing systems of high quality and power.

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, and it shall
be coupled to a tapered throat. The diaphragm shall be phenolic-impregnated linen
for high durability The voice coil shall be edgewound aluminum ribbon of not less
than 100 mm (4 in) in diameter, operating in a magnetic field of not less than 1.9 tesla
(19.000 gaussl. The driver shall be fitted with a waterproof rear cover suitable for the
internal mounting of a line matching transformer, and waterproof gland nut for cable
connections

Performance specifications of a typical 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 2.5 kHz. shall be at least 118 dB SPL. Measured sensitivity with a I W
input at I 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 BI factor shall be at least 19 newtons per ampere.
Frequency response, measured on a terminated tube. shall be flat within ± 5 dB
from 300 Hz to 5.5 kHz. Nominal impedance shall be 16 ohms and power capacity
shall be at least 120 watts normal speech or music program material.

The compression driver shall be the JBL Model 2485J. 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

SPECIFICATIONS:

Throat Diameter:

Nominal Impedance:

Minimum Impedance:12@ 5 kHz

DC Resistance:

Power Capacity¹: 120 W continuous program above 300 Hz

Sensitivity: 111 dB SPL, 1 W @ 1 m on-axis on horn²

Nominal Efficiency: 30% (500 Hz to 2.5 kHz)

Frequency Range: 300 Hz to 6 kHz

Recommended Crossover: 300 Hz or higher, 12 dB/octave minimum

Diaphragm: .23 mm 10.009 in) phenolic

Voice Coil Diameter:

Voice Coil Material: Edgewound aluminium ribbon

Flux Density:

BI Factor: 19 N/A

Positive voltage to black terminal gives diaphragm motion toward the phasing plug

¹Continuous program is defined as 3 dB greater than continuous pink noise and is a

conservative expression of the transduceis ability to handle normal speech and
music program material. Continuous pink noise power ratings are tested with pink
noise input having a 6 dB crest factor. with a high-pass filter set at the specified
lower limiting frequency for two hours duration.

²Sensitivity measured with 1 W 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.

³As specified by recognized standards organizations, sensitivity is measured with the

driver coupled to a terminated tube. The JBL sensitivity rating represents the SPL
in a 25 mm (1 in) terminated tube, using a 1 mW input signal (0.126 V into 16
swept from 500 Hz to 2.5 kHz. The sensitivity rating with a I W input would be

30 dB greater.

Dimensions:

Mounting

Shipping Weight:

49 mm (2 in)
16

8.5

± 10% @ 25°C

118 dB SPL, 1mW on plane-wave tube³

100mm (4 in)

1.9 T (19,000 gauss)

235 mm (911 in) diameter
330 mm (13 in) depth

Four ¼-20 threaded holes, 90° apart
on 101.6 mm (4 in) diameter

Weight:

13.8 kg (30½ lb)

14.5 kg (32 lb)

Response on JBL 2366 Constant Coverage Bi-Radial Horn.
Frequency response of the 2485J coupled to a JBL 2366
Constant Coverage Bi-Radial horn, measured on-axis at a
distance of I meter with a l-watt (4.0 V RMS) input in a
reflection-free environment, with impedance vs. frequency
curve. A horn with a pure exponential flare, such as typical
radial horn designs, will exhibit greater high frequency output
on-axis at the expense of lost angular coverage.

JBL Professional, 8500 Balboa Boulevard, P.O. Box 2200, Northridge, California 91329 U.S.A.

Response on Plane-Wave Terminated Tube. Frequency
response and impedance modulus of Model 2485J coupled
to a 49 mm (2 in) diameter terminated plane-wave tube, with
sensitivity 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 full-range constant
directivity horn design, such as JBL’s 2360 series of Constant
Coverage Bi-Radial Horns.

JBL continually engages in research related to product improvement. New materials production
methods, and design refinements are introduced into existing products without notice as a
routine expression of that philosophy. For this reason. any current JBL product may differ in
some respect from its published description. but will always equal or exceed the original
design specifications unless otherwise stated

7/89 10M SS2485 Printed in U.S.A