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HMS 12 B4-LD-C 300 (12) mm (in.) | 191 (7.52) mm (in.) | 4Ω infinite baffle led subwoofer | 1000 W | 4 Ohm | Single Voice Coil

The new HMS 12 marine classic charcoal grille subwoofer is optimized to perform in open baffle applications for deep and punchy bass without the need to build a dedicated enclosure. HMS 12 is available at 2 or 4-ohm single voice coil versions, featuring a stunning 500 W continuous power handling. The classic grille, features built-in LEDs. The motor and suspension design is optimized for high-power, infinite-baffle operation featuring long linear excursion capability for tremendous output with low distortion.  Hertz Marine subwoofers not only add tons of bass output to your system but also relieve the main speakers from the hard work of reproducing the lowest frequency range, thus maximizing overall system performance for unlimited sound pressure and emotion!
Size mm (in.) 300 (12)
Power Handling - Continuous W 500
Power Handling - Peak W 1000
Impedance Ohm 4
Depth mm (in.) 191 (7.52)
Voice Coil Type single
Voice Coil Ø 65.5 (2.6)
Magnet size D x d x h mm (in.) 156 x 80 x 40 (6.14 x 3.15 x 1.57)
Weight of one component kg (lb.) 7,6 (16.8)
Magnet High density flux ferrite
Cone Polypropylene with UV inhibitors
Technical Specs
D mm 300
Xmax mm 19
Re Ohm 1.8
Fs Hz 30
Le mH 0.41
Vas I 95.4
Mms g 114
Cms mm/N 0.225
BL T*m 8
Qts 1
Qes 1.1
Qms 11.1
Spl dB 89.5
Electro-acoustic Specs
Physical Specs
HMS 12 B4-LD-C
A 342.9 mm 13.5 in.
B 279.4 mm 11 in.
C 192.8 mm 7.59 in.
D 140.6 mm 5.54 in.
F 52.2 mm 2.06 in.
Frequency response
HMS 12 B4-LD-C
HMS 12 B4-LD-C

The HM RGB 1 BK enhances your experience with multicolor LED lighting that can be changed to fit your mood or craft. Is composed by an RGB CONTROLLER specifically developed for HMX LD option models including a radio frequency remote control with a wide


1. Integrated RGB LED lighting to enhance your experience in combination with the HM RGB 1 BK accessory.

2. Sound-transparent sport grille easily removable to be painted with a custom color perfect for your boat.

3. Hertz Pure Marine Certified Product stamp featuring the IP65 protection grade, ASTM-D4329 standards for UV resistance and ASTM-B117 for salt fog operability.

4. Long-throw 50mm (2”) voice coil woofer engineered for infinite baffle application featuring polypropylene cone injected with UV inhibitors and co-molded Santoprene surround.

5. Progressive-design aramid fiber spider with silicone-insulated lead wires ensuring durability and constant performance over time.

6. FEM optimized high-excursion mobile equipment driven by a massive magnetic group encapsulated into a marine-grade polymer injected basket.

7. Gold-plated corrosion resistant brass connection terminals with silicone cap protecting leadwire junction point.

HMS 12 B4-LD-C

Built-in RGB led lighting creates sophisticated atmosphere, adding tons of class to your vessel.

HMS 12 B4-LD-C
HMS 12 B4-LD-C

The protection grade IP65 for speakers define all the Hertz Marine products as totally protected against water jets of different entities, making them highly performant in the marine environment.

HMS 12 B4-LD-C

According to the severe ASTM-D4329 standards for UV resistance, all the materials used for Hertz Marine products are designed to face long time exposition to UV radiations while cruising on the open sea.

HMS 12 B4-LD-C

To satisfy the standards required by ASTM-B117, Hertz Marine products are tested with massive salt fog spray to ensure a complete resistance to corrosion, typical of this atmospheric agent.