Hifonics ZTH-3225.1D Mono Class D Car Amplifier

The Hifonics ZTH-3225.1D is a compact mono car amplifier designed to power a subwoofer or subwoofer system. Its single-channel Class D architecture is intended for installations that need substantial bass amplification without taking up excessive mounting space. It is a practical choice for adding dedicated low-frequency output to an aftermarket car audio system.

This ZEUS Theta amplifier provides adjustable controls to help match its output to the connected subwoofer system and source unit. A variable low-pass crossover, subsonic filter, phase adjustment, and bass control allow the installer to tailor bass response for the vehicle and enclosure. Input-level adjustment supports integration with a range of compatible source-unit preamp outputs.

The ZTH-3225.1D uses a PWM MOSFET power supply designed to provide stable power while minimizing heat generation. Its aluminum heat sink helps dissipate operating heat, which is especially useful when the amplifier is mounted in a confined vehicle location. LED protection indicators provide visible monitoring for overload and speaker-short conditions.

For system flexibility, the amplifier is listed with output ratings of 3,200 watts at 1 ohm, 1,600 watts at 2 ohms, and 800 watts at 4 ohms. Careful impedance planning is important when wiring one or more subwoofers, since the final load determines the applicable output rating. The amplifier's 10Hz to 500Hz frequency response and low-pass crossover controls suit its role in a bass-focused system.

Its compact 14 x 5.75 x 2.5-inch chassis can fit where larger amplifiers may be difficult to mount. Angled, molded terminals help provide easier access for power, ground, and speaker wiring, while nickel-plated RCA inputs support a secure signal connection. A bass remote is included for convenient adjustment of bass level from the front of the vehicle.

Key Features

• Mono Class D Design: Provides dedicated amplification for a subwoofer system in a compact chassis.
• Variable Low-Pass Crossover: Adjusts the subwoofer frequency range from 40Hz to 300Hz.
• Subsonic Filter: Filters frequencies below the selected 10Hz to 40Hz point.
• Bass Adjustment Controls: Includes built-in bass control, 0 to 9dB boost, and a bass remote.
• PWM MOSFET Power Supply: Supports stable power delivery with reduced heat generation.
• Protection Status LEDs: Provides illuminated monitoring for overload and speaker-short protection.

Design & Installation

The ZTH-3225.1D combines a silver aluminum heat sink with a compact amplifier layout. It uses nickel-plated, high-temperature, impact-resistant RCA inputs with hex screw terminals, plus molded angled connection terminals for power, ground, and speaker wiring. The design includes a low-noise preamplifier circuit intended to minimize signal distortion before amplification.

Mount the amplifier securely on a flat surface with adequate ventilation, and do not mount it upside down. Use 4 AWG power wiring, a properly secured chassis ground, and an external 150A fuse placed near the battery; the installation guide specifies fusing the power cable within 18 inches of the battery terminal. Match the connected subwoofer wiring to the amplifier's supported load and set level, crossover, subsonic, and phase controls during system tuning.