JBL Control 321C Installation Instructions Download Page 2

Attaching the loudspeaker/baffle 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/baffle 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 baffle 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 –

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