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Alex Lancaster
08-28-2004, 07:01 PM
Hi:

I have, and plan to use 8 Altec 806s with non OEM phenolic diaphragms, (China, cheap) with JBL 2345s, for voice paging in a big lot, about 55,000 sq ft; I will try stacking, splaying, etc; The question is: Will it help if I put a 10" long tube between the driver and horn, to prevent the diaphragm from unloading?.

I plan to use caps and resistors to avoid any thump or LF from the amp.

Thanks.

whgeiger
08-31-2004, 04:07 PM
AL,

First, please note that the recommendations that follow, anticipate roof and/or tower mounting of driver/horn assemblies for top quality sound into an open, unobstructed, outside area.

To power the drivers, use of a 70-Volt distribution system with line matching transformers at each horn position is recommended. Running long, low impedance lines for this application is contraindicated. In this setting DC blocking capacitors are not required. P.A. power amplifier should provide the desired roll-off, and turn off/on muting.

For this application, the JBL 2345 (800 Hz, short throw) horn is unsuitable. A large format, long throw horn, capable of passing 300 Hz. is preferred. Use of a horn such as the JBL 2366A or equivalent should be considered. For a driver, the JBL 2485J would be a good choice. If a 1 dia. throat driver must be used, then connect two of them to a single horn via a Y adapter.

While using a third party phenolic diaphragm to provide a robust radiator in the Altec 806 driver, clearance between the phase plug and diaphragm may severely limit the higher acoustic output anticipated.

Regards,

WHG

Alex Lancaster
08-31-2004, 05:57 PM
WHG:

Thanks, all advice taken note of; The thing is, I have the horns and a bunch of 1" drivers, I had considered using 2 drivers per horn, and mount them on top of a 2 storey office, protected from rain.