Enclosure Type: Band Pass
Driver Alignment: Subwoofer
Bass Type: Subwoofer
Crossover Type: DSP
Impedance: 8 Ohm
Sensitivity: 99 dB
Cutoff -3 dB: 35 Hz
Diaphragm Material: Paper
Build Complexity: Novice
Radiation Type: Monopole
Type of Use: Public Address
Placement: Outside
Bass Driver Size: 21 inch
Cost of Parts: $1130


single 21”, band-pass subwoofer kit


Key Features

  • High performance 21” subwoofer system
  • Double Reflex Band-Pass design for high output and extended low frequency response
  • Over damped design for better transient response
  • Compact box dimensions
  • Large vent section area for air turbulence and port compression reduction
  • Easy to build design
  • Internal bracing for cabinet loss reducing
  • The enclosure should be made of baltic birch plywood (18mm thickness)
  • Use M4 and M6 bolts. M6 is appropriate for the diver and M4 is suitable for frontal cover.
  • Steel M4 and M6 T-Nuts are recommended
  • Handling, rigging and connectors are at user’s choice. It’s very important that their placement should not influence in any way the proper vent functionality
  • Accurate damping of the cabinet interior, as suggested in the pictures below, is highly recommended: high density synthetic fiber or Polyurethane foam should be used


Internal View
Internal View And Damping
Exploded View
Front View
Top Section
Bottom Section
Top / Bottom View
Side Section
Front Panel Bolt Holes
Eighteen Sound is a leading designer and manufacturer of high quality professional audio loudspeakers, developing state-of-the-art transducer technologies and using the most advanced production techniques, located in Reggio Emilia, Italy.
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