Hertz HMP 4D Marine 4-Channel Class D Amplifier 65W x4 IP64

The Hertz HMP 4D is a marine and powersports Class D 4-channel amplifier rated 50 W x 4 at 4 ohms and 65 W x 4 at 2 ohms RMS (14.4 VDC, 1% THD), bridgeable to 130 W x 2 at 4 ohms, housed in 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.

Full-range bandwidth (10 Hz - 30 kHz) and independent front/rear crossovers make it a one-amp solution for a small system: run four speakers, or use 3-channel mode for a speaker pair plus a bridged subwoofer, or 2-channel bridged mode for higher-power left/right. The front channels offer FULL or hi-pass (65/85/115 Hz @ 12 dB/oct); the rear channels add a lo-pass option at the same frequencies for subwoofer duty. The HI/LO input switch accepts preamp signal (0.2-5 V) or speaker-level signal (0.8-20 V) with ART automatic turn-on, so it connects to a factory head unit with no remote wire, and balanced input circuitry rejects ignition and alternator noise. A nature-proof input connection cable is included.

Sold as a single 4-channel amplifier. Includes the input connection cable, a spare 15 A fuse, four mounting screws, a hex key, and the user's manual. No remote level control is included, and the HMP 4D has no remote-level input.

Specifications

• Class D 4-channel amplifier; minimum load 2 ohms in 4-channel mode, 4 ohms bridged
• Output power (RMS @ 14.4 VDC, 1% THD): 50 W x 4 @ 4 ohms; 65 W x 4 @ 2 ohms; 3-ch: 50 W x 2 + 130 W x 1 (4 ohms); 2-ch bridged: 130 W x 2 @ 4 ohms
• Output power (RMS @ 14.4 VDC, 10% THD): 60 W x 4 @ 4 ohms; 75 W x 4 @ 2 ohms; 150 W x 2 bridged @ 4 ohms
• Bandwidth: 10 Hz - 30 kHz; THD 0.2% (100 Hz @ 4 ohms); S/N 95 dB; damping factor 45
• Filters: FRONT - FULL or hi-pass 65/85/115 Hz @ 12 dB/oct; REAR - FULL, hi-pass, or lo-pass 65/85/115 Hz @ 12 dB/oct
• 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 drives four speakers down to 2 ohms per channel, or a bridged pair/subwoofer at 4 ohms minimum. High-level inputs with ART auto turn-on make it compatible with factory head units that lack remote or preamp outputs.

FAQ

Can the Hertz HMP 4D power a subwoofer?

Yes. In 3-channel mode it runs a pair of speakers plus a bridged subwoofer at 130 W RMS into 4 ohms (1% THD); the rear channels have a built-in lo-pass filter at 65, 85, or 115 Hz. The bridged load must be 4 ohms or higher.

Does the HMP 4D come with, or accept, the HRC BM remote?

No. The HRC BM bass remote ships with (and connects to) the mono HMP 1D only - the HMP 4D has no remote-level input, so level setting is done with its onboard front/rear gain controls.

Is the HMP 4D 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.

What is the lowest impedance the HMP 4D can drive?

2 ohms per channel in 4-channel mode (65 W x 4 RMS at 1% THD) and 4 ohms minimum when bridged (130 W x 2 RMS).