![[Toronto AES Section Logo]](../graphics/logo.gif){kind=logo}
|
|
Toronto AES BulletinMeeting PreviewApril 1997 |
Presented by Jeff
Lissman,
JBL Product Specialist
Touring Sound Systems for Soundcraft Canada
The debut of the HLA Series brings with it the result of three years of research by the engineers at JBL, the new DCD Driver (Dual Coil Drive)-the first lightweight of heavyweight tour sound. This is accomplished using a combination of Neodymium construction and a new voice coil topology which vastly reduces the need for steel.
The DCD approach utilizes two voice coils in each driver. The net effect is a doubling of the power handling capability for each driver; allowing DCD drivers to deliver clean audio at higher power levels than before.
The HLA Series 4895 Three Way High Directivity Horn Loaded Positionable Array Element
As part of their research, the folks at JBL looked for a way to increase the direct-to-reflected sound ratio by decreasing the number of sources heard (i.e.: using highly directive sources that have enough power output so fewer are required). This lead to a new three way MultiBand Waveguide powered by two DCD transducers in a composite magazine with large format compression drivers covering 40 degrees horizontally by 30 degrees vertically.
This composite magazine gives the transducers powering the waveguide the rear compression load required to balance the acoustic resistance provided by the waveguide. Traditionally, this was a simple wood chamber inside a larger wood enclosure. JBL engineers came up with a molded structure that allows for a more precise chamber by utilizing complex shapes. Now the entire transducer motor can be placed outside the chamber for cooling.
SpaceFrame-Aiming To Please
For quick set up and precise coverage, JBL's Spaceframe-a trapezoidal aluminum frame, provides a shell for the MultiBand Waveguide titling system, allowing it to pivot in a vertical plane. SpaceFrame provides pinpoint correct "arraying", while permitting precise vertical coverage from a straight vertical hang by allowing the MultiBand Waveguide to be tilted via the quick release pin. Made of a high strength, lightweight aluminum composites, the system is easy to fly, position, load and aim; eliminating the traditional cabinet structure.
HLA 4897 Subwoofer-Very High Output, Low Frequency Array Element
In the HLA transition, the HLA Sub was also designed with a non-traditional approach. The enclosure is a composite, not wood. An outside skin of carbon fiber (the material F18 fighter planes are made of) is bonded to a honeycomb and foam core that has an inner skin of marine grade fiberglass. This molded shell is than bonded to a composite baffle of carbon fiber and aluminum, which provides a solid inertial ground for the 18" transducers. The entire enclosure is then fastened to the SpaceFrame for extra strength. This way, all energy generated by the transducers is expended moving air, not the baffle or enclosure resulting in increased output. This concept is further aided by a unique, three dimensionally shaped vent. The result is 3dB more output than any other double 18" systems around.
Jeff Lissman, JBL Product Specialist for Touring Sound Systems for Soundcraft Canada, is currently on the road touting the HLA system across North America.
Date: Tuesday April 29, 1997 <--New Date! **
Time: 7:30 pm
Place: Westbury National Show Systems
Address: 772 Warden Avenue (Please access through the North Parking Lot)
(1/2 block south of Eglinton Avenue on the west side of Warden)
Pre-Meeting "Dutch Treat" dinner 5:30 pm at Mardi Gras Restaurant, 777 Warden Avenue
| Toronto AES Home | Current Bulletin | Future Meetings | Back Issues | Search |
This page was created Mon, 14 Apr,
1997 at 21:40.
Please contact TorontoAES@vex.net to report any problems.