JBL Professional 300 User Manual

Accessing the Conduit Knockouts on the

2

3

1

Control 300 Series Backboxes / Backcans

1. On the inside of the backbox (MTC-300BB12)
/ backcan (MTC-300BB8), locate the general area

Knockout

(Exterior View)

of the knockout. Note: Because of the dampening

material’s thickness, you may not be able to feel the
wood cut out however, a cut out is located at each
knockout point.

2. Using a utility knife, cut the dampening material
and remove it from the inside of the box to expose
the conduit knockout. IMPORTANT! To avoid

injury, always wear safety glasses when cutting away
dampening materials.

3. Using a hand held punch, strike the knockout
and remove the seal.

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