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McCauley Sound M421
High-Output 4x21" Touring Subwoofer

OUR PART #:  M421

McCauley Sound's M421 has a continuous power handling in excess of 12,000W and measured peak output of 143 dBSPL at 4 m ground-plane within its operating band.
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McCauley Sound's M421 has a continuous power handling in excess of 12,000W and measured peak output of 143 dBSPL at 4 m ground-plane within its operating band.  With a well-shaped response from 20 to 100Hz and a total weight under 500 lbs, the M421 delivers an unprecedented level of low frequency energy for its size.  The M421's design features four, independently powered, 21" long excursion neodymium motor transducers.  Specially designed 6.0" voice coils exhibit near linear force factor (Bl) through the entire range of cone motion.  The drivers are configured in an isobaric assembly and coupled to an FEA optimized acoustic transformer.  With integrated handles, casters, skids, travel dolly, and optional fly ware, the M421 is a versatile and powerful sound reinforcement subwoofer.

The enclosure is constructed of multi-ply void-free birch hardwood plywood and is coated with a weather and wear resistant ProCoat™ polyurethane hybrid finish.  Components in the front of the enclosure are protected by a flat grill made from perforated 11 gauge steel that is coated with heat cured epoxy powder.  All rigging and hardware is weather protected with a heat-cured epoxy powder coat finish.

Main PA Applications:

  • Amphitheater
  • Arena
  • Dance/DJ Club
  • Distributed/Zone Outdoor
  • General Staging


  • High efficiency
  • Maximum SPL
  • Integrated locking skids
  • Integrated casters & handles

Performance Parameters:

  • System Type: Quad 21" subwoofer
  • Frequency Response, -10 dB: 16Hz-120Hz
  • Frequency Response, +/-3 dB: 20Hz-85Hz
  • Sensitivity (LF): 110dB @ 2.83V/1m
  • Maximum SPL (LF, Continuous/Peak):
    149 dB / 155 dB (calculated 1m ground plane)
    143 dB (measured 4m ground plane, pink noise processed 20-85Hz)
  • Power Ratings (continuous/peak):
    Total Program Power: 12000W/16000W
    LF1: 3000W @ 8 ohms
    LF2: 3000W @ 8 ohms
    LF3: 3000W @ 8 ohms
    LF4: 3000W @ 8 ohms

Physical Properties:

  • Weight: 489 lbs (226 kg)
  • Dimensions: 23.1" H x 73.4" W x 44" D (586.7 x 1864.3  x 1117.6 mm)
  • Enclosure Material: 5/8" multi-ply Birch laminate
  • Hardware: Integrated locking skids on two face
    NOTE: Install version available without casters & handles (contact your sales representative for more information)
  • Finish: Black Procoat™ Polyurea-Hybrid Weatherproofing
  • Transducers (LF): 4x 21" cone transducers, 6" voice coil, neodymium motor
  • Connectors: Neutrik NLT8*
    *Required for maximum output due to connector maximum voltage rating
  • Optional accessories: M421 dolly, M421 fly kit, MB421 rigging frame (contact your sales representative for more information)

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