JBL 4311b Manual

							Smooth, powerful, wide-range response within a compact 
enclosure. 
Components: 300 mm (12 in), long excursion, low fre- 
quency loudspeaker; 130 mm (5 in) midrange loudspeaker; 
36 mm (1.4 in) high frequency direct radiator; matched fre- 
quency dividing network with front panel controls for mid- 
range and high frequency output. 
90” dispersion allows vertical or horizontal placement. 
A product of JBL’s long experience and intimate involve- 
ment with the recording industry. the 43llB is a powerful, yet 
compact monitor loudspeaker system. Its wide-band re- 
production 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 mag- 
netic 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 fre- 
quency 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 hav- 
mg 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 cop- 
per voice co11 drives a 100 mm (4 in) edge-damped cone that 
operates as a true piston, provldmg smooth frequency re- 
sponse 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  
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 load- 
ing of the low frequency loudspeaker. 
2213H 
LE252 
LE5-10 
3112BNetwork notshown 
LE25-2  
						

							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. Con- 
trols are continuously variable from maximum to full off. 
With suitable settings of the two controls, the frequency re- 
sponse 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 
The accompanying graph and specifications were com- 
piled 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 environ- 
merit; a calibrated condenser microphone was suspended 
at a known distance from the sound source, sufficiently 
far to 
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 wide- 
angle 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 impress- 
ive performance characteristics, they cannot convey the full 
impact of an extended listening evaluation. Clean, crisp, 
wide-range performance, even at very loud levels, power- 
ful 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. Response 
Frequency resPo”se of the 43llB taken with ‘V-octave band pink Norse. Measured 
at 1 m with a l-watt (“put 
35 Hz Output 
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 
)  
						

							Specifications JBL continually engages in research related to product improvement. New mate- 
rials, production methods and design refinements are introduced into existing 
Power Capacity’ 75 W continuous program products without notice as a routine expression of that philosophy. For this rea- 
son, any current JBL product may differ in some respect from its published de- 
Crossover Frequencies 1.5 and 6 kHz scription but will always equal or exceed the original design spectflcations unless 
Nominal lmpedence 6 R otherwise siated. 
Hugh Frequency 
Drspersion 
Frequency response 
Sensitrvrty* 
Drstortron 
M Power, 95 dB 
SPU3 m (loft), 
Single Frequency 
Finish 
Grille 
Dimensions 
Net Weight 
Shipping Weight 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 
21 kg 45 lb 
24 kg 52~lb 
‘Continuous program power IS defined as 3 dB greater than continuous sine wave 
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 re- 
sponse 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 
Professional Division 
James B. Lansing Sound, Inc., 
8500 Balboa Boulevard, 
Northridge, California 91329 U.S.A.