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(Read from slide)
JBL’s 3000-series cinema loudspeakers have been designed with as narrow a front-back profile as good engineering allows. They are intended for use in smaller theaters where depth behind the screen is usually very limited. The systems have been optimized in terms of sensitivity, power handling, and physical size, and can keep pace with today’s demands for clean, non-distorted sound quality.
The 3677 screen channel system is self-contained two-way design intended for small budgets and small theaters. Its key features are its shallow profile and built-in passive network with high frequency driver protection that will ensure safe operation under all operating conditions.
The 3678 is THX approved for screen channel use In biamp mode for theaters no larger than 3678 cubic meters (45,000 cubic feet), and screen-to-back-row distances no greater than 12.2 meters (40 ft). Key features are its shallow profile, Bi-Radial horn for smooth horizontal and vertical dispersion at high frequencies, and its built-in high frequency driver protection.
The 3310 is JBL’s lowest cost surround loudspeaker and is recommended for use with the 3000-series screen loudspeakers. It fits the same wall mounting bracket that is used with the 8330 and 8340 surround loudspeakers.
The model 3635 low-cost subwoofer is intended for use in small cinemas. It features a single 300 watt 460 mm (18 inch) diameter transducer, and its front-to-back depth is only 380 mm (15 inch).
(Read from slide)
The 4675 system pioneered new ground by being the first theater system to provide directivity matching between adjacent components at crossover. The system provided both uniform axial response and uniform power response from 200 Hz upward. The system was adopted as the first THX standard when Lucasfilm set up their THX theater certification program. Alternate versions are available, with and without passive networks. The model 4670 was developed later for those houses that lacked the behind-the-screen depth necessary for the 4675.
The 4645C subwoofer provides response down to 25 Hz with remarkably low distortion. Used in multiples, these units are responsible for the most awesome low end imaginable!
The surround models 8330 and 8340 represent ongoing efforts to provide a family of attractive, easy to mount surrounds that almost instantly became the favorite of both the professional film industry as well as the public exhibition industry. These products heralded in the era of “more but smaller” surrounds and have truly come into their own in today’s digital era.
Because it was the first system to gain THX approval, the 4675 system described here was subsequently “copied” numerous times by both domestic and foreign suppliers in an effort to gain their own THX certification..
Using state of the art JBL 2226 low frequency drivers and the equally regarded 2446 high frequency compression driver, the system is capable of mid-band instantaneous peak levels of 105 dB at a distance of 20 meters (66 ft).
The system is designed for bi-amplification. The enclosure is ruggedly built, and the integral horn mounting bracket, model 2506, facilitates precise horn aiming.
Normally operated via a passive dividing network, the 4675C screen channel system is a natural choice for medium to large theaters in multiplex installations. With a system power rating of 600 watts (IEC noise spectrum) and a sensitivity of 100 dB (one watt at one meter), the 4675C can produce instantaneous peak direct field levels of 102 dB at a distance of 20 meters (66 ft).
The 4670D is an economical dual woofer screen system designed high output capability in mid-sized cinemas. It is a shallow system with passive crossover and is intended for use in spaces where vertical pattern control in the midrange is not critical.
The 4645C is based on the 2242H low frequency transducer, a device capable of sustained power input of 800 watts. In this system, the enclosure tuning is at 25 Hz, which means that cone excursion is minimal at that frequency, even for very high power input. As a result, the system can deliver very high levels of fundamental output in that range. Under half-space (single boundary) mounting conditions, response is -10 dB at 18 Hz.
This is the 4641 subwoofer.
This is a 600 watt subwoofer featuring an advanced technology 460 mm (18 inch) low frequency transducer. The 2241H transducer utilizes the same patented Vented Gap cooled process as the 2242 transducer in the 4645C. This has a usable response to 25 Hz and is THX approved.
This is a 1200 watt dual 18 subwoofer featuring two 460 mm (18 inch) transducers. The 4642A is ideal for low frequency augmentation of either analog or digital soundtracks.
Which surround model to choose?
For houses with seating no greater than about 200 patrons, use either moderate or high power surrounds.
For houses with seating greater than 200 patrons, always use high power Surrounds.
With an IEC noise power rating of 100 watts and a sensitivity of 91 dB (one watt at one meter), a single 8330 can produce an instantaneous midband level of 111 dB at a distance of 1 meter. At a more realistic distance of 6 meters (20 ft), the peak level would be 95 dB.
Surround loudspeakers are always used in multiples, normally 8 or 12 per surround channel. If we consider 6 meters as the average distance from a typical listener to all of the surround loudspeakers, the effect of 8 surrounds would increase the overall level by 9 dB, giving an average peak level in the house of 104 dB. The use of 12 surrounds would produce a peak level, per surround channel, of 106 dB. Normally the reason for specifying 12 over 8 surrounds is not for the sake of more level, but for better diffusion of the surround effect.
System response is switchable between flat on-axis and rolled off high frequency response corresponding to recommended equalization practice in the film industry.
Which surround model to choose?
For houses with seating no greater than about 200 patrons, use either moderate or high power surrounds.
For houses with seating greater than 200 patrons, always use high power Surrounds.
Purely in terms of output capability, irrespective of directional advantages, the 8340 will provide nearly 8 dB more output than the 8330, on a per-unit basis. Most of this capability is used at the frequency extremes in digital effects tracks.
In many theaters, 8330 surround channels are being retrofitted with the 8340, which has exactly the same mounting requirements. Like the 8330, the 8340’s system response is switchable between flat and rolled off.
JBL’s 5000 Series three-way systems are the latest iin cinema sound quality. These products were designed taking into account the new demands of digital sound tracks, and they bring together many of JBL’s recent engineering advances.
The three systems in the 5000-series are normally specified according to seating capacity. The small system is intended for cinemas up to 250 seats, or a room volume up to 1216 cubic meters (45,000 cubic feet), while the middle system is intended for cinemas up to 500 seats, or a room volume of 2700 cubic meters (100,000 cubic feet). The large system is intended for use in cinemas up to 1200 seats, or a room volume of 6080 cubic meters (225,000 cubic feet).
JBL recommends the use of 8340 surround loudspeakers and 4645C subwoofers with the 5000-series.....
The 5000-series screen loudspeakers bring together several of JBL’s advances over recent years. Since the high frequency section of the system works only above 2500 Hz, it has been redesigned with Optimized Aperture high frequency horns and drivers, resulting in distortion that is 8 to 10 decibels lower than the previous designs.
A new midrange horn and driver have been introduced into the cinema loudspeaker art, providing controlled output over the critical range from 300 Hz to 3000 Hz. This is a true compression driver design -- not a horn-loaded cone driver.JBL’s Vented Gap Cooling low frequency transducers are used to ensure cool operation with low power compression over long operating periods.
Digital signal processing is used to provide all aspects of frequency division, time correction, and system power response and room equalization. Preset tunings for the 5000-Series are included.
All components of the system have matching radiation patterns at the crossover frequencies; this contributes to uniform coverage and smooth power response in the cinema.
The Academy of Motion Picture Arts and Sciences, Beverly Hills, CA, has had JBL systems in its prestigious Samuel Goldwyn Theater since the early 1980s. In March, 1997, the Theater Standards Committee of the Academy approved the installation of five screen channels of JBL’s new three-way system, the model 5674, and comments from the membership of the Academy have been uniformly enthusiastic. We at JBL Professional believe the concepts embodied in this system point the future directions that theater sound will take everywhere.
JBL ScreenArray®
The JBL ScreenArray® three-way loudspeaker system, incorporates the latest advances in JBL’s research into;
High performance transducers
Multi-band Waveguides
Crossover designs
ScreenArray - Advanced Design Featuresv
6 Key Technological Advances:
1. “Three Way” Design
2. “Tapered” Midrange Line Array
3. Filtered Array Technology.
4. Waveguide loaded cone-type midrange transducers
5. Screen Spreading Compensation
6. Asymmetrical Midrange and High Frequency Waveguides
JBL ScreenArray®
3632 / 3632T
4632 / 4632T
JBL ScreenArray®
3632 ScreenArray® System;
•Designed for small to medium auditoriums
•
•Bi-amp or Tri-amp versions available
•
•3632-T (Tri-amp) is THX Approved
•
•30 Hz to 20 kHz frequency range
•
•129 dB peak SPL
•
•Multi-band Waveguide
JBL ScreenArray®
4632 ScreenArray® System;
•Designed for medium to large auditoriums
•
•Bi-amp or Tri-amp versions available
•
•4632-T (tri-amp) is THX Approved
•
•30 Hz to 20 kHz frequency range
•
•135 dB peak SPL
•
•Multi-band Waveguide
TWO-WAY
ScreenArray® Systems
The new Two-Way ScreenArray® Systems
provide smooth and accurate reproduction of cinema soundtracks
in a compact
and VERY cost effective package
Two-Way ScreenArray®
•JBL Professional meets the challenge of low cost cinema systems while utilizing the most advanced technology in cinema today
•
•The low distortion ScreenArray® horn combined with JBL low frequency technology provides clear, accurate reproduction of the mid/high frequency information
•
•Provides all the benefits of extended high frequency response and controlled coverage at a Very Competitive Price
3622N, 2-Way ScreenArray®
FEATURES:
•JBL 2374 ScreenArray® horn with Screen Spreading Compensation
•
•JBL 2418H-1, 44mm (1.75in) Diaphragm High Frequency Compression Driver
•
•Second Generation Optimized Aperture Waveguide Technology for Ultra Low Distortion and Extremely Low Frequency Response
•
•NEW 3639 Dual 15” Low Frequency System
•
•Fully Passive Operation utilizing a computer optimized crossover network
•
•Pre-assembled Components to reduce field assembly time - lower installation cost
4622, 2-Way ScreenArray ®
FEATURES:
•JBL 2384 ScreenArray® HF horn with Screen Spreading Compensation
•
•JBL 2430H, 75mm (3 in.) Diaphragm High Frequency compression driver
•
•Second Generation Optimized Aperture Waveguide Technology for ultra low distortion
•
•JBL 4639 Dual 15” Low Frequency System
•
•Bi-Amplified design
•
•Pre-assembled Components to reduce field assembly time - lower installation cost
•
4622N, 2-Way ScreenArray ®
FEATURES:
•All of the features of the 4622 Two Way ScreenArray® System in a FULLY PASSIVE SYSTEM design.
•
•4622 N utilizes a sophisticated crossover network, developed using computer optimization technology providing seamless transition.
•
- This results in excellent power response and controlled directivity.
JBL ScreenArray® Cinema Systems;
The most advanced, cost effective Screen-channel systems in the world
4632-T 3-Way ScreenArray® Tri-amplified (THX)
3632-T 3-Way ScreenArray® Tri-amplified (THX)
4632 3-Way ScreenArray® Bi-amplified
3632 3-Way ScreenArray® Bi-amplified
4622 2-Way ScreenArray® Bi-amplified
4622N 2-Way ScreenArray® Passive
3622N 2-Way ScreenArray® Passive
Television Academy
Leonard H. Goldenson Theatre
Theater Systems
A Practical Guide to Selecting Screen Loudspeakers, Surround Loudspeakers and Subwoofers
by David Fuller
Screen channel requirements;
15” LF drivers in the 95 - 97 dB SPL sensitivity range
(1 Watt at 1 meter).
LF power handling in the 300-watt range and…….
HF systems with matching output capability.
House sizes based on THX survey.
Low frequency driver count
(per “screen” channel)
For houses with 200 seats or less, specify systems with one LF driver per channel.
For houses with 200-to-500 seats, specify systems with two LF drivers per channel.
For houses with more than 500 seats, specify systems with four LF drivers per channel
Remember than you can always specify a larger system for a smaller house - but not vice versa
Placement of screen channels
Space horizontally to match the widest picture format.
Elevate systems so that the HF sections are up about 2/3 the screen height.
Place the systems so that the HF elements are as close as possible to the screen.
Paint matte black any reflecting surfaces.
“Toe-in” of screen loudspeakers
Regardless of whether the screen is curved or not, “toe” the outside loudspeakers inward so that their on-axis extensions intersect at a point 2/3 of the distance to the back wall.
Downward tilt of HF elements
Tilt the HF elements downward so that they point at ear level at a distance 2/3 toward the back of the house.
Surround channel requirements;
Moderate power surrounds (dome tweeter):
Sensitivity: 91 dB SPL (1 W at 1 m)
Power Rating: 100 watts continuous
High power surrounds (compression driver):
Sensitivity: 96 dB SPL (1 W at 1 m)
Power Rating: 250 watts continuous
Maximum output difference: 9 dB
Which surround model to choose?
For houses with seating no greater than about 200 patrons, use either moderate or high power surrounds.
For houses with seating greater than 200 patrons, always use high power Surrounds.
How many surrounds?
In most houses the ideal number will be between 12 and 16
Normally, specify at least 4 surrounds on back wall
An exception here is in very small houses, where there may be two on the back wall. In this case, a total of 8 surrounds may suffice (3 on each side; 2 at back)
How to position the surrounds
The front-most surrounds are normally 2/3 the distance from the back wall to the screen.
The back-most side wall surrounds should be about 9 - 12 feet from the back wall.
Surround height and aiming
Height should normally be 12 - 15 feet above the floor.
The high frequency axis should be aimed at the seats on the opposite wall.
Be prepared for Surround EX
Ideally, the three surround channels should have the same output capacity, and this calls for an equal number of loudspeakers per channel.
When possible, specify surrounds in a quantity divisible by 6
(eg. 12, 18 or 24) to ensure optimum paralleling
Selecting Surround Amplifiers
Choose stereo amplifiers with a generous 4-ohm power rating that equals twice the individual surround loudspeaker rating.
For example, if using high-powered surrounds (250 watt @ 8 ohm), select a stereo amplifier that can deliver 500 watts per- channel into 4-ohms.
If you have followed these rules:
Surround coverage in the back 2/3 of the house will be uniform to ±2 dB.
Fine tuning “drive” levels may further improve uniformity.
In deep houses, be prepared to “zone” surrounds with delay to maintain proper front - back perspectives
Subwoofer channel requirements;
Use 18-inch diameter drivers.
Sensitivity: should be no less than about 97 dB,
(1 W, at 1 m)
Power ratings per driver should be no less than about 400 watts Continuous.
How many subwoofer drivers are needed?
A safe rule is to specify one sub driver for each 700 m 3 of house volume.
Always round up;
if your calculations then indicate 5 ˝ subs, use 6!
You can always specify more subs for greater impact
Subwoofer powering
We recommend driving each subwoofer transducer with its own amplifier channel.
Choose amplifiers with an output rating commensurate with each transducer at its rated impedance.
Subwoofer mounting
Mount the sub-woofers at the base of the screen, as close as possible to the floor and wall intersection.
Cluster the individual units together as tightly as possible in order to take maximum advantage of their “mutual coupling”.