Hertz HMP 1D Marine Mono Class D Subwoofer Amplifier 300W IP64

The Hertz HMP 1D is a marine and powersports Class D mono subwoofer amplifier rated 250 W RMS x 1 at 2 ohms and 150 W RMS x 1 at 4 ohms (14.4 VDC, 1% THD; 300 W and 180 W at 10% THD), built into an IP64-rated cast-aluminium chassis for boats, UTVs, ATVs, and motorcycles. It is a universal 12-volt component with no vehicle-specific fitment. Hertz certifies the HMP line to its Pure Marine standard: IP64 protection grade, ASTM-D4329 UV resistance, and ASTM-B117 salt-fog operability, with marine-grade epoxy-coated circuit boards.

Setup is handled on the amp itself: a switchable low-pass filter (65/85/115 Hz @ 12 dB/oct, or FULL to bypass), a subsonic filter (Off/22/32 Hz @ 12 dB/oct), and a selectable bass boost (Off/+6/+9 dB). Balanced input circuitry rejects electromagnetic interference from ignition and charging systems, and the HI/LO input switch accepts head-unit preamp signal (0.2-5 V) or speaker-level signal (0.8-20 V) with automatic turn-on (ART), so it wires into a factory source with no remote lead. The included HRC BM remote knob adjusts subwoofer level from the driver's seat.

Sold as a single mono amplifier. Includes the HRC BM remote level control, a 5 m (196.85 in) remote extension cable, a spare 15 A fuse, four mounting screws, a hex key, and the user's manual.

Specifications

• Class D mono (1-channel) amplifier; minimum load 2 ohms
• Output power (RMS @ 14.4 VDC, 1% THD): 150 W x 1 @ 4 ohms; 250 W x 1 @ 2 ohms
• Output power (RMS @ 14.4 VDC, 10% THD): 180 W x 1 @ 4 ohms; 300 W x 1 @ 2 ohms
• Bandwidth: 10-500 Hz (subwoofer duty); damping factor 300 (100 Hz @ 4 ohms); S/N 105 dB; THD 0.1% (100 Hz @ 4 ohms)
• Filters: low-pass 65/85/115 Hz @ 12 dB/oct (or FULL); subsonic Off/22/32 Hz @ 12 dB/oct; bass boost Off/+6/+9 dB
• Inputs: PRE IN, LO 0.2-5 V or HI 0.8-20 V speaker-level with ART automatic turn-on
• Power supply: 11-15 VDC; 1 x 15 A fuse; consumption 15 A max @ 2 ohms, 14.4 VDC
• Protection: IP64; ASTM-D4329 UV; ASTM-B117 salt fog; short-circuit and thermal protection with auto reset
• Dimensions: 223 x 100.5 x 43.6 mm (8.77 x 3.95 x 1.70 in); weight 1.35 kg (2.97 lb)

Compatibility

Universal 12-volt negative-ground installation: any boat, UTV, ATV, motorcycle, car, or truck. It pairs with any subwoofer presenting a 2-ohm or higher final load - a single 2-ohm sub, a dual-voice-coil sub wired to 2 ohms, or two 4-ohm subs in parallel. The high-level inputs and ART auto turn-on make it compatible with factory head units that have no remote or preamp outputs.

FAQ

Is the bass remote included with the Hertz HMP 1D?

Yes. The HRC BM remote level control and a 5 m extension cable are in the box, so you can adjust subwoofer level from the driver's seat with no extra purchase.

Is the HMP 1D waterproof?

No. It is IP64 rated - protected against dust and splashing - and certified for UV and salt-fog exposure, but Hertz's manual states it is not water-proof and must be installed in a dry compartment with no direct contact with water.

Can the HMP 1D run door or tower speakers?

No. It is a mono bass amplifier with a 10-500 Hz bandwidth, intended for subwoofers only. For full-range speakers, use the 4-channel Hertz HMP 4D.

What is the lowest impedance the HMP 1D can drive?

2 ohms. At 2 ohms it delivers 250 W RMS (1% THD, 14.4 VDC); at 4 ohms it delivers 150 W RMS.