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Excellence is an elusive quality It's so easy to recognize yet so difficult 

to attain 

JBL craftsmen have been involved in the art of sound (or more than 

a generation signal and source, wood and fabric, transducers and 

acoustics—all of it 

Today these craftsmen continue to perform to the most rigid standards 

any craftsman can submit to: those they impose upon themselves. 

JBL loudspeakers are carefully engineered instruments, painstakingly 

crafted and assembled to watchmakers' standards. JBL enclosures 

express the excitement of creative design; they are elegant, solid and 

flawlessly finished. JBL transducers and electronics offer what has been 

characterized by devoted music listeners as the incomparable JBL sound.' 

By following the few simple suggestions contained in this booklet, 

you can look forward to superb high fidelity reproduction that will retain 

its clarity and realism year after year. 

Introduction 

Every JBL loudspeaker system is the product of extensive listening 

evaluation combined v/ith exhaustive research and testing, using the most 

sophisticated equipment and methods available. JBL system recommen-

dations are based on subjective evaluation of component performance 

as well as efficiency and eleclrical characteristics These and other critical 

factors must be integrated by a frequency dividing network engineered 

for the specific components of the system 

A well-built, sturdy enclosure is essential for optimum bass performance. 

An enclosure having the proper internal volume and tuning for the loud-

speaker increases low frequency dynamic range and improves tonal 

quality: it also reduces distortion and the possibility ol overdriving the 

loudspeaker. 

Detailed guidance on enclosure construction may be obtained from 

your JBL Loudspeaker Components dealer who may also supply the 

JBL Enclosure Construction Kit. An illustrated brochure with a discussion 

of loudspeaker theory as woll as detailed enclosure construction tuning 

and finishing instructions for home entertainment and musical instrument 

applications is contained in the kit Actual construction drawings and 

"Loudspeaker Components by JBL' nameplates for your finished 

enclosures are also included. 

JBL transducers are precision instruments responding with high accuracy 

to the variations in electrical current produced by other components in 

the music system Extraneous noises, such as hum. rumble, crackling 

or hissing do not originate in the loudspeakers If you experience difficulty 

realizing the fine performance built into your JBL components, consult 

the JBL Loudspeaker Components dealer from whom they were 

purchased. He is equipped with the knowledge required to provide expert 

advice and assistance. If. for some reason, your JBL dealer is unable to 

assist you, or you cannot find the answer you need published in JBL 

literature, write directly to the JBL Technical Services Department describ-

ing the difficulty in detail: please be certain that your return address and 

telephone number are clearly printed on your correspondence. 

Summary of Contents for 124H

Page 1: ......

Page 2: ...ontinually engages in research related to product improvement New materials production methods and design relinements are introduced into existing products without notice as a routine expression ol th...

Page 3: ...essential for optimum bass performance An enclosure having the proper internal volume and tuning for the loud speaker increases low frequency dynamic range and improves tonal quality it also reduces...

Page 4: ...ent is properly adjusted and the overall volume level of the sound system should be reduced In almost all cases the acoustic level generated by a JBL loudspeaker will become noticeably discomforting t...

Page 5: ...peaker system is complete Mounting In An Enclosure Widest sound distribution will be realized and response through the midrange region will be just a little more natural and transparent when a loudspe...

Page 6: ...ize 1 ront Mount Rear Mounl Boll Circle Diymoior Frame Mourning Hoie Drill Size Front Mount Rear Mount D208H 179 mm 7X m 179 mm 7Vi in 194 mm 7 in 5 4 mm in 5 8 mm m b 8 mm 1 LE8T H t 7 9 m m 7M m Noi...

Page 7: ...s are attached to the center of the PR15C The fiberboard disc in fronl of them is integral to the passive radiator and must not be removed Each of the metal discs weighs 100 grams Six fiberboard discs...

Page 8: ...D130H 380 mm 15 in extended rango 45 Hz 130H 380 mm 15 in lowfrequency D208H 200 mm 6 in extended range 55 Hz I system tuning is higner than recomn eindcd for the loudspeake covai a portun pi the non...

Page 9: ...o moderate density with fiberglass acoustic damping material A sub chamber can be fabricated of a tube having an internal diameter of 114 mm 4ftin and a length of 130 mm 5 in flush mounted on the baff...

Page 10: ...I 105 mm Diameter 075 077 Mounting Dimensions 075 Or 077 Installation Install the 077 as shown lor widest sound distribution in the horizontal plane LE21H Mounting Dimensions...

Page 11: ...support the driver However the driver must be separately braced or removed from the enclosure whenever the loudspeaker system is transported since under such circum stances it is possible lor the wei...

Page 12: ...10...

Page 13: ......

Page 14: ...with staples or small carpet tacks As the lens is removed from the tape a ripping sound will be heard indicating normal disengagement A clearance of 67 mm 2 in between the baffle panel and the grille...

Page 15: ...Adjustment of the level control should be made on the basis of evaluation of normal program material played monaurally with amplifier tone controls at the middle generally referred to as flat position...

Page 16: ...the control assembly of the larger LX30 LX50A and LX80A Wood screws as well as machine screws and T nuls are pro vided to secure the assembly to the enclosure Be certain that the white vinyl flange ga...

Page 17: ...s well as the horn lens assembly utilized The wiring illustrations are correct when an HI 87 HL91 HL92 or HL93 is mounted on the enclosure baffle panel and when an HL88 HL89 or I1L90 is positioned so...

Page 18: ...strations Noie The color codes illustrated represent the latest configuration Earlier units were supplied with Iwo black wires instead ot green black and yellow black wires and a red wire instead of I...

Page 19: ...The color codes illustrated represent the latest configuration Earlier units were supplied with two black wires instead ol green black and yeilow Wack wires and a red wire instead ol Ine yellow wire...

Page 20: ...The color codes illustrated represent the latest configuration Earlier units wore supplied with two black wires instead ot green black and yellow black wires and a red wire instead of the yellow wire...

Page 21: ...tie Black Input Terminal Ol The N7000 Network YELLOW BLACK Note The color codes illustrated represent the latest configuration Earlier units were supplied with two black wires instead of green black a...

Page 22: ...mi nal of the primary net work would have lieen connected to the red torrrvna of the com YELLOW BLACK pression driver connect it to the red input of this network YELLOW Note The color codes illustrate...

Page 23: ......

Page 24: ...will be energized and the compression driver will be phased as if it were still connected 10 Ihe network When Ihe swilch is thrown tho phase of the driver will be reversed II is recommended thai Ihe...

Page 25: ...er trom whom It was purchased If it is not possible to contact a dealer write directly to the JBL Service Department describing the difficulty as fully as possible Products returned to the factory mus...

Page 26: ...James B Lansing Sound Inc 8500 Balboa Boulevard Northridge California 91329 50711 IMLCS 7 S0 Printed n U S A...

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