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Precision Directivity™ Speakers from JBL Professional offer New Solutions for Arenas, Stadiums and all Large Installations
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NORTHRIDGE, CA
- OCTOBER 24, 2001 - One of the challenges in large arenas, stadiums,
houses of worship and performance spaces is to provide quality sound
to every seat with the volume and clarity demanded by today's concert,
sporting and special events. JBL Professional's new Precision Directivity™
(PD) line of speakers uses a full range, full bandwidth total system
approach that allows contractors and consultants to design a fully
integrated sound system that solves the audio challenges inherent
to these types of large installations. JBL PD™ mid/high frequency
loudspeakers utilize a new co-axial design, with specific coverage
angles that allow the sound to be aimed precisely at individual sections
of the audience area for high intelligibility and maximum fidelity.
Another problems that PD technology solves is how to provide low frequencies
(bass) evenly to every seat. JBL Engineering developed the new Precision
Directivity technology that effectively allows the low frequencies
to be "steered" at specific areas of the arena to assure
even bass coverage throughout.
PD has progressed
beyond the idea or prototype stage. Fully functional systems are already
installed in high profile arenas and an outdoor sports facility. Once
again, JBL is launching an important new product with a successful
track record in prestige installations. At the 2000 PLASA Show in
London in September, JBL Professional introduced the VERTEC™
Line Array loudspeakers, which were successfully employed at the high-profile
Democratic National Convention a month earlier. In late July, 2001,
two months prior to the product's introduction, the American Airlines
Center in Dallas opened with its JBL sound system, which included
several new PD designs.
"PD Series
is the result of a fast-track development program by the JBL Custom
Shop and JBL R&D in conjunction with some of our key customers
and the Harman Professional Projects Group," explained JBL Professional
President Michael MacDonald. "Last year, in discussions with
the designers of several large arenas, we felt we had a new approach
to help them design large speaker systems with predictable and manageable
coverage patterns. Control and intelligibility are the results of
the new PD Series."
Designers WJHW
of Dallas and Impulse Group of Minneapolis were in the process of
developing world-class sound systems for new arenas in Dallas and
North Dakota. American Airlines Center and Ralph Engelstad Arena were
destined to be premier, spare no expense arenas and the sound systems
were required to meet very high standards. In each case, based upon
early demonstrations of PD technology and the reputation of JBL and
its Custom Shop, PD Series speakers were selected for these prestigious
installations.
Seven models
are being introduced. They are:
_ PD162 - Mid bass array with six 12" drivers per enclosure
_ PD162U4 - Mid bass array with four 12" drivers
_ PD162L4 - Mid bass array with four 12" drivers
_ PD125 - Dual 15" low frequency array
_ PD128 - Dual 18" very low frequency subwoofer array
_ PD743 - Co-axial mid/high frequency enclosure with 40° x 30°
coverage
_ PD764 - Co-axial mid/high frequency enclosure with 60° x 40°
coverage
Low Frequency PD Systems
JBL Professional has developed three modular forward-steered low-frequency array systems.
The PD162, with six 12-inch drivers per enclosure, reproduces the
125 Hz to 300 Hz upper-bass range. The PD 125 has two 15-inch drivers
and is designed for low frequencies in the 50 to 250 Hz range. PD128,
with two 18-inch drivers per enclosure, works in the 30 Hz to 125
Hz lower-bass range. Steerable arrays are formed by using individual
enclosures in multiples and applying the proper signal processing.
By having separate arrays for each of these low frequency bands, excellent
audience coverage and off-axis rejection are achieved.
For the PD162
mid-bass arrays, the steering is accomplished by progressively delaying
each pair of low-frequency transducers to a reference plane that is
perpendicular to the direction in which the array is being steered.
To maintain wide horizontal coverage, the array is kept as narrow
as possible in that direction. In another unique design innovation,
the transducers are mounted "motor out" to reduce the horizontal
width of the array and to assist in cooling, which reduces power compression.
The PD125 works
in a fashion similar to that of the PD162, but with a different mechanical
configuration dictated by the larger size of its 15-inch drivers and
their requirement for greater internal enclosure volume.
Due to longer
wavelengths at frequencies where the PD128 Subwoofer Array operates
and the larger enclosure volume required for response to 30 Hz, a
different configuration is required. Greater spacing of the elements
is necessary to effectively steer the energy since the wavelengths
involved are longer. As with the upper-bass array, the lower-bass
array is forward-steered by progressively delaying each set of modules.
The two arrays can be used to compliment each other as they are optimized
in their physical arrangement to effectively steer their main energy
lobe and to accurately reproduce program in their frequency range.
The result is powerful, coherent low frequency energy with optimized
polar response.
The PD128 and
PD162 are intended to work together to form the subwoofer/low frequency
and mid bass sections of a four-way system when combined with PD Series
mid/high enclosures. The PD125 forms the low frequency section of
a three-way PD System for applications where the 30 Hz extension of
the PD128 is not required.
Mid/High Frequency Enclosures
The PD764 60°
x 40° and the PD743 40° x 30° devices are the first two
mid/high Precision Directivity speaker systems. The audio requirements
of stadiums and arenas such as Dallas' American Airlines Center require
a new design for high-powered co-axial mid/high-frequency arena speakers
using dual high-frequency drivers. Co-axial arrangements allow much
smaller frontal area than the traditional designs with HF and MF elements
adjacent to one another, which means more compact arrays are possible.
Since a co-axial design is inherently axis-symmetrical, the problem
of an asymmetrical polar pattern caused by physical offset between
mid and high frequency drivers is avoided. Before PD technology, physically
large high-frequency drivers mounted in front of the midrange section
have tended to partially obstruct the midrange sound, making this
a compromised solution.
With the recent
development of JBL's new compact, powerful 2430 compression driver,
JBL determined that good-sounding, well-behaved high-output co-axial
speaker systems could now be successfully developed. The driver is
only 108 mm (4.25 in) in diameter and with its high energy neodymium
magnet weighs less than three pounds. The very small cross-sectional
area of the 2430 drivers allows the HF section to be acoustically
transparent to the midrange wavefront.
To obtain the
required midrange output, the system takes advantage of JBL's latest
generation dual-voice coil Neodymium Differential Drive® technology.
The model 2250 high-power 400-Watt 8-inch transducer delivers the
equivalent output of a 10-inch or 12-inch driver cone transducer,
but with smaller size and lower moving mass that is preferable for
midrange reproduction. This allows for closer driver spacing and results
in a system with very high output with about half the distortion and
less destructive interference than previous co-axial systems.
By using two
of these high-output midrange drivers and two of the physically smaller,
high-output compression drivers, the system is capable of long-term
sound pressure level performance of 144 dB at one meter in both the
high and mid-frequency bands or about 112 dB long-term average SPL
at the typical arena's 120-foot throw distances.
PD Series speakers
from JBL Professional are now in production. For more information
on these speakers and for technical support in their application,
contact the Harman Professional Projects Group at 818-895-3497.
Headquartered
in Northridge, California, JBL Professional is the world's leading
designer, manufacturer, and marketer of professional loudspeakers
for recording and broadcast, musician, cinema, touring sound, commercial
sound and contracting applications. JBL Professional is part of the
Harman International network of professional and consumer audio companies.
For complete product and company information, go to the JBL Pro website
at www.jblpro.com.
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Copyright © 2002 JBL Professional
All Rights Reserved |
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