JBL Control 321C User manual

Control 321C/CT & 322C/CT
Installation Instructions
MTC-300BB12 Backbox
Shown as Cut-Away for Clarity
1
Line up EZ-Rail™ with one of the
the backbox anges containing a sin-
gle mounting hole. For orientation
when holding the speaker overhead,
two embossed arrows on the under-
side of the metal bafe indicate the
edge with the EZ-Rail.
Slide EZ-Rail onto the ange of the
JBL MTC-300BB12 (or compatible
other brand) backbox.
– Over –
23
EZ-Rail helps to hold one side of
the speaker bafe TEMPORAR-
ILY during installation while the
installer installs the screws that hold
the bafe.
IMPORTANT
The installer MUST secure the
bafe in place with screws on all
sides.
Loudspeaker
Pre-Mounted
Metal Bafe
EZ-Rail™

Attaching the loudspeaker/bafe securely in place with screws:
Using JBL’s MTC-300BB12 Backbox – MTC-300BB12 is compatible with two common mounting systems for in-
stalling the loudspeaker/bafe to the backbox. Either of these mounting systems may be utilized. Screws are included
with the MTC-300BB12 backbox.
Using A Different-Brand Compatible Backbox -- Screwholes in the metal bafe are provided corresponding with
two common mounting systems. Utilize the system that works with that particular backbox.
Mounting Option #2
Using 4 pcs 4 mm Machine Bolts
2 Points at Each Side
1 Point at Each End
Mounting Option #1
Using 6 pcs #10 Sheet Metal Screws
1 Point at Each Corner
4 pcs 4 mm x 14 mm
Threaded Machine Bolts
(included with JBL MTC-300BB12 backbox).
Use with Backbox’s 4 Threaded
Insert Points, shown above.
6 pcs #10 x 0.75 inch
Sheet Metal Screws
(included with JBL MTC-300BB12 backbox)
Use with Backbox’s 6 Speed Nuts (also called Clip Nuts or
Tinnerman Nuts), shown above.
4
JBL Professional
8500 Balboa Boulevard, P.O. Box 2200
Northridge, California 91329 U.S.A.
361089-001
8/05
MTC-300BB12
Backbox Shown
– OR –