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JBL's MTC-300BB12 Three-Cubic-Foot Backbox features extra-thick 16-gauge metal construction and a thick resonance-eliminating lining that also provides extra bass response. Made for the Control 300 Series 12" Drivers, this backbox has a dual-mounting system for baffle and knockouts on all four sides.

This back box has a five-year warranty from JBL Professional.



  • Extra-thick 16 gauge metal construction.
  • Lined with 12 mm (½ inch) thick MDF to eliminate resonances and to provide extra bass response.
  • Knockouts on top and all four sides.
  • Dual mounting system for baffle.
  • Mounting platform for an optional high-power 70V/100V transformer.

JBL MTC-300BB12 Best-in-Class Three Cubic Foot Back Box for 12" Models

  • External Volume 3 cu ft, nominal
    Internal Volume 2.4 cu ft.
    Knockouts 22.1 mm (0.87 in) diameter opening
    Five (5) locations: 
    1 on top panel
    1 on each side and end
    Height 308 mm (12.1 in) above ceiling
    324 mm (12.6 in) total height
    Width 587 mm (23.1 in)
    Depth 461 mm (18.2 in) cabinet
    505 mm (19.9 in) including side tabs
    Ceiling Cut Out 378 x 378 mm (14.9 x 14.9 in)
    Shipping Weight 23.1 kg (51 lbs)
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