Name: SX118+
Rating: 4.7 (23 reviews)

The SX118+ is a compact, high‑performance subwoofer that extends the system’s low‑frequency operating range to 38 Hz and delivers impressive output for such a compact enclosure.

Features

Compact, direct radiating reflex-loaded subwoofer
18” (460mm) long-excursion driver, 4” (100mm) voice coil, neodymium motor, waterproof cone
High output capability
Tour-grade plywood enclosure with M10 mounting points
Available in black or white

Applications

Touring sound reinforcement for small and medium-size venues
Fixed installations in concert halls, theatres, ballrooms and houses of worship
Sports stadiums, arenas and corporate AV events
Restaurants, bars and hotel entertainment areas
Concourses and theme parks

SX118+ features a long‑excursion 18 in (460 mm) driver with a 4 in (100 mm) voice coil, a water‑resistant cone and a triple‑roll surround in a compact reflex enclosure. The driver design maximises output while minimising power compression and distortion. The four reflex ports have a large frontal area to reduce turbulent air noise at very high levels and the internal port geometry promotes laminar airflow.

The enclosure is built from multi‑laminate birch ply, finished with a durable polyurethane coating and fitted with a stainless‑steel grille, twin grab handles, skids, M10 mounting points (with internal brackets) for installation and a threaded pole socket for pole‑mounting point‑source loudspeakers. Cabinet wheels and a transit cover are available as optional accessories.

Compared with the SX118, the SX118+ [Shipping Q2 2026] is an all‑new design with enhanced performance and features. It is slightly larger, so it uses a new transit cover, and it includes new drivers and an improved cabinet.

The SX118+ adds a third NL4 input connector on the front to improve cabling for subwoofers used in cardioid configurations. For outdoor use, you no longer need a WRKIT, but you must seal all three NL4 sockets. Use the correct cable connectors (NLT4FX or NLT4FX‑BAG) for connected sockets and install a Martin Audio weatherproof NL4 sealing plug in any unused socket.

The SX118+ has two LED indicators, one on the front and one on the back, which you can illuminate via Vu‑Net software to identify each enclosure on the circuit. The rear LED is intended for use in cardioid setups.

Links

User guide Brochure Datasheet Settings [v2.2]

Specification

TYPE	Compact, direct radiating reflex-loaded subwoofer
FREQUENCY RESPONSE (1)	38Hz – 100Hz ±3dB, -10dB @ 31Hz
DRIVER	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
RECOMMENDED AMPLIFIER	iK41, iK42, iK81, bridged for full output
	For details, see SX118+ User Guide
SENSITIVITY (3)	99.5 dB
MAXIMUM SPL (2)(3)	131dB continuous, 137dB peak
	143dB peak with crest factor 4
NOMINAL IMPEDANCE	8 ohms
DISPERSION (-6dB)	Omni-directional or cardioid when paired
ENCLOSURE	Multi-laminate birch ply
FINISH	Textured black or white paint
PROTECTIVE GRILLE	Black or white perforated stainless steel
Environmental Testing (for details click here)	IP rating IP21 MIL-STD-810H ISO 4892-2 Solar Radiation ISO 12944-6 Category C3 Corrosion resistance
LED INDICATORS	Two LEDs: one front, one rear (rear LED for cardioid subs)
CONNECTORS	3 x NLT4MPXX-BAG (one front, two rear) IP54 weather-resistant seal with NLT4FX, NLT4FX-BAG or weatherproof NL4 sealing plug

PIN CONNECTIONS (INPUT ON FRONT)	1+/1-
PIN CONNECTIONS (INPUT ON REAR)	1+/1-
PIN CONNECTIONS (LINK ON REAR)	1+/1- linked to 1+/1- 2+/2- linked to 2+/2-
FITTINGS	Two skids on base, with mating channels on top M20 top-mounted thread plate for pole mounting 20 x M10 mounting points, 5 on top, 5 on bottom, 4 on left, 4 on right, 2 on back 2 x bar handles, one on each side 16 x M8 inserts for optional castors
DIMENSIONS (INCL SKIDS)	(W) 650 mm x (H) 603 mm x (D) 635 mm (763 mm with castors) (W) 25.6 in x (H) 23.7 in x (D) 25.0 in (30.0 in with castors)
WEIGHT	49.2 kg (109 lbs), 52.5 kg (116 lbs) with castors
ACCESSORIES	Pack of four castors WHEELKIT M10 eye bolt HTKCT06 Weatherproof NL4 sealing plug Transit Cover SX118+TC

Architectural Specs

SX118+

The loudspeaker shall be a compact, direct‑radiating, reflex‑loaded subwoofer consisting of an 18‑inch (460 mm) long‑excursion low‑frequency transducer. The on‑axis frequency response shall be 38 Hz–100 Hz ±3 dB, with a ‑10 dB point at 31 Hz. The loudspeaker shall produce a maximum SPL 137 dB peak or 143 dB peak with crest factor 4.

Power handling shall be 1500 W AES, 6000 W peak, and the rated impedance shall be 8 ohms. The loudspeaker shall be fitted with three NL4 connectors (one on the front and two on the rear). The loudspeaker shall be operated in conjunction with a dedicated controller amplifier.

The enclosure shall be constructed from multi‑laminate birch plywood with a textured black (RAL 9005) or white (RAL 9016) paint finish. The driver shall be protected by a perforated stainless‑steel grille, and the enclosure shall be fitted with two skids on the base with mating channels on top, an M20 top‑mounted threaded pole‑mount plate, 20 M10 mounting points, bar handles and inserts for optional castors. Two LED indicators, one front and one rear, shall allow enclosure identification via Vu‑Net, with the rear LED intended for cardioid operation.

Dimensions including skids, excluding castors (W × H × D) shall be 650 mm × 603 mm × 635 mm (25.6 in × 23.7 in × 25.0 in). Dimensions including castors shall be 650 mm × 603 mm × 763 mm (25.6 in × 23.7 in × 30.0 in). Weight shall be 49.2 kg (109 lb) or 52.5 kg (116 lb) with castors.

The loudspeaker shall be the Martin Audio SX118+.

Technical Drawings & 3D Models