Hifonics ZTH-1225.1D Mono Class D Car Amplifier

The Hifonics ZTH-1225.1D is a compact mono car audio amplifier designed to power a subwoofer system. Its single-channel Class D design provides a space-conscious solution for adding dedicated low-frequency amplification to a vehicle. It is suited to system upgrades where a separate bass amplifier is needed without using a large mounting area.

This amplifier is rated for up to 1,200 watts at a 1-ohm load, with lower listed output ratings at 2 and 4 ohms. That range gives installers options when matching compatible subwoofer wiring configurations. Its 10 Hz to 500 Hz frequency response and variable low-pass crossover support subwoofer-focused use.

Onboard controls allow the amplifier to be adjusted for the vehicle and subwoofer system rather than relying on a fixed setup. The low-pass crossover, subsonic filter, bass boost, phase adjustment, and input level control provide practical tuning points. A wired bass remote is included for convenient adjustment of bass level from the front of the vehicle.

The ZTH-1225.1D uses a PWM MOSFET power supply and an aluminum heat sink. This design combines a compact Class D amplifier layout with heat-dissipating aluminum construction. LED protection diagnostics provide visible indication of overload or speaker-short protection status.

For system integration, the amplifier offers RCA inputs as well as speaker-level audio inputs. Its compact 7.8-inch length can make it easier to place in locations such as a trunk, cargo area, or under a seat when ventilation and secure mounting are available. It is a focused option for adding a mono subwoofer channel alongside a factory or aftermarket source unit.

Key Features

• Mono Class D Design: Delivers a dedicated single channel for subwoofer amplification in a compact chassis.
• 1-Ohm Rated Output: Listed at 1 x 1,200 watts at 1 ohm.
• Variable Low-Pass Crossover: Adjusts the bass cutoff from 40 Hz to 300 Hz.
• Subsonic Filter: Provides adjustable filtering from 10 Hz to 40 Hz.
• Included Bass Remote: Lets the user adjust bass level from the listening position.
• Protection Indicators: Illuminated diagnostics monitor overload and speaker-short protection.

Design & Installation

The amplifier has a silver aluminum heat sink, a PWM MOSFET power supply, and molded power, ground, and speaker connection terminals. Its RCA inputs are nickel-plated and designed for secure connections using hex-screw terminals. The angled terminal layout helps provide access for wiring and a cleaner cable-routing profile.

Mount the amplifier securely on a surface with adequate ventilation and do not install it upside down. Use 4 AWG power and ground cable, a properly placed external 60A fuse, and speaker wire up to 12 AWG as specified for this model. Connect signal through RCA or speaker-level inputs, begin with the level control set to minimum, and tune the crossover, subsonic filter, phase, and bass controls for the connected subwoofer system.