JBL 3678-HF Setup Instructions

SET-UP INSTRUCTIONS FOR 3678 SCREEN CHANNEL SYSTEM

High Frequency Horn Bracket assembly:

The horn bracket that is shipped with the 3678-HF kit provides aiming flexibility in all directions. It requires
minor field assembly, and takes only several minutes to complete.
The bracket assembly consists of three parts:
• Driver Clamp
• "L"-shaped Clamp Base
• Hardware pack
One (1) 1/4"-20x5/8" Philips pan head bolt
One (1) 1/4"-20 nut with captive "star" washer
One (1) #8-32x1/2" Philips pan head bolt
One (1) #8-32 nut with captive "star" washer
One (1) cable assembly for connecting HF driver to network
Be sure you have all of these components before you begin.
STEP 1: Secure L-shaped clamp base to 3678-LF enclosure. Remove the large Philips-head bolt from
the top of the enclosure*, and use it to fasten the L-shaped clamp base
to the cabinet so that the section with five holes is on the left-hand
side, as you face the enclosure (see diagram). Note that although the
T-nut on the top of the enclosure may appear to be off-center, the
upright section of the "L" is on the centerline, when properly positioned
and secured into the T-nut.
STEP 2: Secure bracket clamp/driver/horn assembly.
Position clamp around the upright section of the clamp base so that it
"sandwiches" the base. Secure clamp using the large 1/4"-20 Philips
pan-head bolt (main clamp bolt) and nut through the center (largest)
hole on the upright section of the clamp base.
STEP 3: Aim horn. Using one of the four remaining positioning
holes, the horn can be pitched in one of four fixed positions; +3° or
+5° upward tilt, -5° downward tilt, or 0° (no tilt).
The entire bracket assembly can also be free rotated 360° ("yaw",
or side-to-side aiming) around the enclosure top mounting bolt.
The driver/horn can also be rotated (if necessary) simply by
loosening clamp bolt, rotating the driver/horn within the clamp to
desired position, then re-tightening the main clamp bolt.
Note that when the horn/driver is fixed into position, it is accurately physically "time aligned" to the low
frequency driver in the 3678-LF enclosure.
* NOTE: NEVER use this T-nut as a hang point for the 3678-LF enclosure. The enclosure was not designed for
suspension, and the T-nut is not intended to support any weight.

3678-LF Network Wiring Instructions:

The internal network of the 3678-LF (low frequency section) can be used to operate the system in either
- comes pre-installed around the rubber "tire" on the 2425HS driver.
(P/N 423-00007-67)
(P/N 423-00008-67)
- inserted in cardboard packing material;
(P/N 229-00005-00)
page 1 - 3678 Owner's Manual
rev. 2.0 11/11/98
- inserted in cardboard packing material
+5 degrees
+3 degrees
Clamp base
(shown with bottom section facing the viewer)
980-00023-00
centerline of enclosure
. . . .
main clamp bolt
-5 degrees
0 degrees
CE