Martin Audio SX218+

The Martin Audio SX218+ is a high-performance dual-driver reflex-loaded subwoofer engineered for demanding touring and installation applications requiring exceptional low-frequency output and impact. Featuring two advanced 18-inch long-excursion neodymium drivers with 4-inch aluminium voice coils, waterproof cones, and optimized suspension systems, the SX218+ delivers deep, powerful bass with outstanding transient response and minimal distortion. With low-frequency extension down to 31Hz and an impressive maximum output capability, it is ideally suited for large-scale professional sound reinforcement systems.

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Key Features

• Dual-driver direct-radiating reflex-loaded subwoofer
• Two 18-inch long-excursion low-frequency drivers
• High-performance neodymium motor structures
• 4-inch aluminium voice coils
• Waterproof cones for enhanced durability
• Exceptional low-frequency extension down to 31Hz (-10dB)
• Extremely high output capability
• Fast transient response with low distortion
• Omnidirectional or cardioid operation when paired
• Tour-grade birch plywood enclosure
• Available in black or white finish
• Integrated flying and installation hardware options
• Weather-resistant connectivity system
• LED status indicators for system monitoring

Technical Specifications

• Type: Dual-Driver Direct-Radiating Reflex-Loaded Subwoofer
• Frequency Response: 38Hz – 100Hz (±3dB), -10dB @ 31Hz
• Drivers:
  • 2 × 18″ (460mm) Long-Excursion Drivers
  • 4″ (100mm) Aluminium Voice Coils
  • Neodymium Motors with T-Poles and Demodulation Rings
  • Waterproof Cones
• Power Handling: 3000W AES, 12000W Peak
• Recommended Amplifier:
  • iK42 (Bridged for Full Output)
• Sensitivity: 102.5dB
• Maximum SPL:
  • 137dB Continuous
  • 143dB Peak
  • 149dB Peak (Crest Factor 4)
• Nominal Impedance: 4 Ohms
• Dispersion: Omnidirectional or Cardioid (When Paired)
• Enclosure Material: Multi-Laminate Birch Plywood
• Finish: Textured Black or White Paint
• Grille: Black or White Perforated Stainless Steel
• Environmental Ratings:
  • IP21
  • MIL-STD-810H Tested
  • ISO 4892-2 Solar Radiation
  • ISO 12944-6 Category C3 Corrosion Resistance
• LED Indicators:
  • Front LED
  • Rear LED (For Cardioid Configurations)
• Connectors:
  • 3 × NLT4MPXX-BAG
  • One Front Connector
  • Two Rear Connectors
• Weather Protection:
  • IP54 Seal with NLT4FX, NLT4FX-BAG or Weatherproof NL4 Sealing Plug
• Input Connections (Front):
  • 1+ / 1-
• Input Connections (Rear):
  • 1+ / 1-
• Link Connections (Rear):
  • 1+ / 1- Linked to 2+ / 2-
  • 2+ / 2- Linked to 1+ / 1-
• Pole Mount:
  • M20 Thread Plate on Right Side for Portrait Configuration
• Mounting Points:
  • 24 × M10 Mounting Points
    • 6 Top
    • 6 Bottom
    • 4 Left
    • 4 Right
    • 4 Rear
  • 16 × M8 Inserts for Optional Castors
• Handles:
  • 4 Bar Handles (2 per side)
• Additional Features:
  • Base Skids with Mating Top Channels
• Dimensions (W × H × D): 1091 × 538 × 827 mm
• Dimensions with Castors: 1091 × 538 × 955 mm
• Weight:
  • 82.3 kg (Without Castors)
  • 85.5 kg (With Castors)