Features and Applications
Features
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Applications
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Product Details SX118+
SX118+ extends the low-frequency system response to 38 Hz at the lower ±3 dB boundary. A long-excursion 18-inch driver uses a 4-inch voice coil, neodymium motor, water-resistant cone and triple-roll surround.
Four large reflex ports reduce turbulent airflow, with revised internal geometry promoting laminar flow. The multi-laminate birch cabinet has polyurethane paint and a protective stainless-steel grille.
Twin handles, locating skids, M10 points with internal brackets and a threaded pole socket support installation and portable use. Black and white finishes are available.

The 2026 design uses new drivers and an improved cabinet compared with SX118. Its slightly larger dimensions require the model-specific transit cover. Wheels and a cover are optional accessories.
A third NL4 socket on the front simplifies cabling when a cabinet faces backwards in a cardioid arrangement. Outdoor connections no longer use the older WRKIT, but all three sockets must be sealed: NLT4FX or NLT4FX-BAG connectors on cabled sockets and Martin Audio weatherproof plugs on unused sockets.
Front and rear LEDs can be illuminated through VU-NET to identify cabinets on the circuit. The rear LED supports identification in cardioid setups.
Explore the Martin Audio SX subwoofers at B-Star for the available system options.
Technical Specifications SX118+
ACOUSTICS |
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| TYPE | Compact, direct radiating reflex-loaded subwoofer |
| FREQUENCY RESPONSE (1) | 38Hz – 100Hz ±3dB, -10dB @ 31Hz |
| DRIVERS | 18 in (460 mm) long-excursion driver with 4 in (100 mm) aluminium voice coil, neodymium motor with T-pole and demodulation ring, waterproof cone |
| RATED POWER (2) | 1500W AES, 6000W peak |
| SENSITIVITY (3) | 99.5 dB |
| MAXIMUM SPL (2) (3) | 131dB continuous, 137dB peak; 143dB peak with crest factor 4 |
| NOMINAL IMPEDANCE | 8 ohms |
| DISPERSION AT −6 dB | Omnidirectional, or cardioid when paired in the specified configuration |
EXTERNAL PROCESSING AND AMPLIFICATION |
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| RECOMMENDED AMPLIFIER | iK41, iK42, iK81, bridged for full output; For details, see SX118+ User Guide |
CONNECTIONS AND INDICATORS |
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| LED INDICATORS | Two LEDs, one front and one rear; rear LED for cardioid subwoofer operation |
| CONNECTORS | 3 × NLT4MPXX-BAG connectors (one front, two rear); IP54 weather seal with NLT4FX, NLT4FX-BAG or weatherproof NL4 blanking plugs |
| FRONT INPUT PIN CONNECTIONS | 1+/1− |
| REAR INPUT PIN CONNECTIONS | 1+/1− |
| REAR LINK PIN CONNECTIONS | 1+/1− linked to 1+/1−; 2+/2− linked to 2+/2− |
ENCLOSURE, MOUNTING AND ENVIRONMENT |
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| ENCLOSURE | Multi-laminate birch ply |
| FINISH | Textured black or white paint |
| PROTECTIVE GRILLE | Black or white perforated stainless steel |
| FITTINGS | Two skids with mating channels in the top; top-mounted M20 threaded pole-mount plate; 20 × M10 fixing points: 5 top, 5 bottom, 4 left, 4 right, 2 rear; 2 × bar handles, one per side; 16 × M8 inserts for optional castors |
| ACCESSORIES | Four-castor WHEELKIT; M10 HTKCT06 eyebolts; weatherproof NL4 blanking plugs; SX118+TC transit cover |
| ENVIRONMENTAL TESTING | IP21; MIL-STD-810H; ISO 4892-2 solar radiation; ISO 12944-6 Category C3 corrosion resistance |
DIMENSIONS AND WEIGHT |
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| DIMENSIONS INCLUDING SKIDS | 650 × 603 × 634 mm (W × H × D); depth 762 mm with castors. Equivalent to 25.6 × 23.7 × 25.0 in; depth 30.0 in with castors. Values follow the 2026 datasheet; the website lists depths of 635/763 mm. |
| WEIGHT | 49.2 kg (109 lbs), 52.5 kg (116 lbs) with castors |


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