Hifonics ZD-750.4D 4-Channel Class D Car Amplifier

The Hifonics ZD-750.4D is a compact four-channel Class D car amplifier designed to add dedicated power to a vehicle audio system. It can drive front and rear speakers in a conventional four-channel setup or be configured for bridged operation with compatible 4-ohm loads. Its compact chassis helps make it a practical option where amplifier mounting space is limited.

This amplifier is suited to listeners upgrading from head-unit power and seeking more output for component speakers, coaxials, or a mixed speaker-and-subwoofer system. It delivers 100 watts per channel at 4 ohms or 175 watts per channel at 2 ohms. For two-channel bridged applications, it is rated at 375 watts per channel into 4 ohms.

Variable high-pass and low-pass filters let installers direct appropriate frequencies to speakers or subwoofers. The crossover ranges from 50 Hz to 250 Hz with a 12 dB-per-octave slope. A built-in bass control provides an additional low-frequency adjustment option.

The ZD-750.4D uses a PWM MOSFET power supply and Class D topology for efficient power delivery in a relatively small enclosure. A low-noise preamplifier circuit, nickel-plated RCA inputs, and a 0.2 to 6V input-sensitivity range support integration with a broad range of source units. Its aluminum heat sink is designed to dissipate heat during normal operation.

For installation flexibility, the amplifier supports speaker-level audio inputs and RCA connections. DC Signal Sense can switch the amplifier on when a signal is received at the RCA inputs, eliminating the need for a remote turn-on wire in applicable systems. Protection indicators monitor overload and speaker-short conditions, helping provide at-a-glance system status.

Key Features

• Four-Channel Class D Design: Powers front and rear speakers or supports bridged two-channel operation.
• Variable Electronic Crossover: Helps match frequency output to full-range speakers or subwoofers.
• PWM MOSFET Power Supply: Provides stable power delivery with efficient Class D operation.
• DC Signal Sense: Can turn the amplifier on from an RCA input signal.
• Speaker-Level Inputs: Supports connection in systems without dedicated RCA preamp outputs.
• LED Protection Diagnostics: Indicates overload and speaker-short protection status at the amplifier.

Design & Installation

The ZD-750.4D has a black aluminum heat-sink chassis, nickel-plated high-temperature RCA inputs, and molded terminals for power, ground, and speaker wiring. Angled connection terminals are intended to improve access and help maintain a cleaner wiring path. The amplifier measures 10.82 inches long, 6.89 inches wide, and 3.15 inches high.

Use 4 AWG cable at the 12V and ground terminals, install the specified external 60A fuse, and use up to 12 AWG speaker wire at the speaker terminals. Match each full-range channel to a 2-ohm or higher speaker load, or use 4-ohm loads when bridging channels. Set the input sensitivity and crossover controls during installation to suit the source unit, speakers, and intended system configuration.