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Smooth, powerful, wide-range response within a compact
enclosure.
Components: 300 mm (12 in), long excursion, low frequency loudspeaker; 130 mm (5 in) midrange loudspeaker;
36 mm (1.4 in) high frequency direct radiator; matched frequency dividing network with front panel controls for midrange and high frequency output.
90” dispersion allows vertical or horizontal placement.
A product of JBL’s long experience and intimate involvement with the recording industry. the 43llB is a powerful, yet
compact monitor loudspeaker system. Its wide-band reproduction at loudness levels required in professional work
make the 43llB ideally suited for control room installations,
small studios, mixdown facilities, broadcast monitors and
portable playback systems.
Low Frequency Loudspeaker
Bass material is reproduced by a powerful, long excursion,
300 mm (1’2 in) loudspeaker having a 75 mm (3 in) diameter
edgewound copper ribbon voice coil operating in a magnetic field of 1.0 T (10,000 gauss). The magnetic assembly
weighs 4.7 kg (10% lb); free air resonance is approximately
22 Hz. The surface of the cone is coated with an exclusive
damping formulation that provides the precise mass and
density necessary to optimize bass performance, prevent
spurious resonance and provide smooth performance ex-
tending into the midrange region.
Midrange ‘Eansducer
Transition to the mldrange urut 1s made at a crossover frequency of 1.5 kHz. The 130 mm (5 m) transducer provides
clarity and freedom from audible dIstortIon, even at the high
loudness levels encountered m professional appllcatlons.
The transducer IS energized by a magnetic assembly havmg a total weight of 0.74 kg (1% lb) and creatmg a magnetic
field of 1.35 T (13,500 gauss). The 22 mm (% m) diameter copper voice co11 drives a 100 mm (4 in) edge-damped cone that
operates as a true piston, provldmg smooth frequency response and wide dispersion throughout Its operating range.
High Frequency Direct Radiator
Reproduction above 6 kHz is accomplished by a 36 mm (1.4
in) direct radiator. Its 0.74 kg (1% lb) magnetic assembly ana
16 mm (% in) diameter copper voice coil drive a cone and
center dome with controlled linearity assured by an impregnated cloth termination. The voice coil, suspended in a
magnetic field of 1.5 T (15,000 gauss), is unusually large in
relation to cone size for high efficiency and exceptional transient response. The small cone diameter is responsible for
wide, uniform dispersion of high frequency energy: a ring of
dense foam surrounds the moving assembly to damp unwanted radiation and reflections.
Frequency Dividing Network
The frequency dividing network installed in the 43llB has
been designed and tested to achieve the smoothest possible
transitions between component loudspeakers. All network
components are of the highest quality, Capacitors are noninductive, non-polarized types with high AC current
capacity, built expressly for use in dividing networks and individually tested for conformity to rigid performance standards.
Enclosure
As with all JBL loudspeaker systems, the component transducers, frequency dividing network and enclosure are designed and tested to function as a single, integrated unit.
The enclosure is solidly constructed of 19 mm (% in) stock
throughout with wood-welded joints to prevent unwanted
resonance. Internal padding absorbs spurious reflections
and standing waves. All components mount directly to the
baffle panel and are removable from the front of the
enclosure. A ducted port provides proper acoustical loading of the low frequency loudspeaker.
<Y
,>
2213H
LE252
LE5-10
3112BNetwork notshown
LE25-2
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Adjustable Response Contour
he frequency dividing network of the 43llB is provided with
front panel controls to allow separate regulation of output in
the 1.5 kHz to 6 kHz range and the region above 6 kHz. Controls are continuously variable from maximum to full off.
With suitable settings of the two controls, the frequency response contour of the 4311B can be altered to compensate for
almost any acoustical environment, or to achieve the tonal
balance desired. Control scales are clearly marked so that
special settings can be logged and easily reset when
needed.
Performance Characteristics
Response
Frequency resPo”se of the 43llB taken with ‘V-octave band pink Norse. Measured
at
1 m
with a l-watt (“put
The accompanying graph and specifications were compiled from measurements made under standard laboratory
test conditions. The loudspeaker system was mounted flush
in.the.center of a large, flat baffle in an anechoic environmerit; a calibrated condenser microphone was suspended
at a known distance from the sound source, sufficiently
far
be safely out of the near field: and all electronic equipment
was checked and calibrated before tests were run.
The on-axis frequency response of a typical 43 11B does not
vary more than 23 dB from 45 Hz to 15 kHz. Due to the wideangle characteristics of the midrange and high frequency
units and their physical orientation, response measured up
to 45” off axis, horizontally or vertically, does not deviate
more than 6 dB from on-axis response at 2 kHz nor more than
10 dB at 8 kHz. The 43llB’s lack of distortion is equally out-
tanding. Distortion is inaudible even at high power levels
b&d at very low frequencies, as shown in the photo at right.
While specifications indicate that the 43 11B has impressive performance characteristics, they cannot convey the full
impact of an extended listening evaluation. Clean, crisp,
wide-range performance, even at very loud levels, powerful bass fundamentals without doubling and lifelike voice
projection are qualities found in few loudspeaker systems,
regardless of size or price. When heard from a monitor oc-
cupying less than 71 litres (2.5 ft3), the effect is little less than
awesome.
35 Hz Output
to
This unretouched photo shows the acoustic output of the system when dwen by a
50 W Sine wave slgnal at 35 Hr. A laboratory microphone was used to pick up the
sound from the 43118 The signal from the microphone was connected directly to
a” o~~lll~S~oPe and the trace Photographed.
Sustained Performance at this lntenslty would not be encountered during normal
“se. A 50 W Sine wave represents a far more dlfflcult job for the loudspeaker than ,ts
rated capactty of 75 W program mawal, particularly in the very low frequency
range Even so. 11 can be seen that the 43118 produces an almost perfect sine
wave.
(Note Below 50 Hz, most loudspeaker systems produce substantial dtstortion with
an Input of only a few watts
)
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Specifications
Power Capacity’ 75 W continuous program
Crossover Frequencies 1.5 and 6 kHz
Nominal lmpedence 6 R
Hugh Frequency
Drspersion
Frequency response
Sensitrvrty*
Drstortron
M Power, 95 dB
SPU3 m (loft),
Single Frequency
Finish
Grille
Dimensions
90” horrzontal and vertrcal
45 Hz - 15 kHz t3 dB
91 dB. 1 W, 1 m (3 3 ft)
42 dB, 1 mW, 30 ft (9 1 m)
Less than 1% third harmonrc
generation from 100 Hz to 15 kHz
Textured arav or oiled walnut
Black fabrrc
597 mm x 362 mm x 296 mm deep
23fi in x 14% In x 113/4 in deep
Net Weight
Shipping Weight
21 kg 45 lb
24 kg 52~lb
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 spectflcations unless
otherwise siated.
‘Continuous program
power @MS) It is a conservallve expression of a loudspeaker systems ablllty to
handle normal speech and muw program material
ZMeasured wth Input swept from 500 Hz lo 2 5 kHz with controls set for flattest response Unlike many theater type loudspeaker systems that exhlblt sensltlwty
peaks I” the mldrange the JBL Control Monitor provides substantially the same
sensltlwty through the full range of audible frequencies Measured serwtlwty below
500 Hz or above 2 5 kHz may be corwderably greater than that of other systems
with higher sensltlvlty ratings
power IS
defined as 3 dB greater than continuous sine wave
Professional Division
James B. Lansing Sound, Inc.,
8500 Balboa Boulevard,
Northridge, California 91329 U.S.A.
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