Rockford Fosgate T400X4AD 400W 4-Channel Amplifier

The Rockford Fosgate T400X4AD is a compact four-channel car amplifier designed to add clean, controlled power to a vehicle speaker system. Its 400-watt rated total output supports a conventional four-speaker layout or a two-channel bridged setup. The small chassis helps solve installation-space limitations in cars, trucks, motorcycles, and side-by-side vehicles.

This amplifier is suited to listeners upgrading factory-powered speakers or building an aftermarket full-range system. It supplies 100 watts RMS to each of four channels at either 4 ohms or 2 ohms, allowing flexible speaker matching within its rated load range. When bridged, it delivers 200 watts RMS to each of two 4-ohm channels.

Class-AD circuitry and Constant Power operation are central to the T400X4AD design. The amplifier maintains its rated 100-watt-per-channel output at both 4-ohm and 2-ohm stereo loads. This makes it practical for systems where installation needs or speaker wiring determine the final impedance.

Integrated crossover controls help tailor the signal for full-range speakers, tweeters, midbass drivers, or a bridged pair of compatible speakers. High-pass, low-pass, and all-pass selections are available, with adjustable high-pass and low-pass points from 50 Hz to 250 Hz. Punch EQ provides separate bass and treble adjustment for modest system voicing changes.

The T400X4AD accepts front and rear high-level or low-level signals through harness connections, making it suitable for factory-radio and aftermarket-head-unit installations. Its high-level input capability includes automatic turn-on, reducing the need for a separate remote-turn-on connection in applicable installations. C.L.E.A.N. input and output clip indicators assist with setting source volume and amplifier gain during system setup.

Key Features

• Four-Channel Constant Power: Delivers 100 watts RMS per channel at 4 or 2 ohms.
• Bridged Operation: Combines channels for 200 watts RMS x 2 at 4 ohms.
• Class-AD Topology: Provides efficient full-range amplification in a compact enclosure.
• High- and Low-Level Inputs: Supports aftermarket radios and compatible factory speaker-level signals.
• C.L.E.A.N. Clip Indicators: Helps set source level and amplifier gain with visual feedback.
• Adjustable Crossovers and Punch EQ: Enables basic speaker filtering and tonal adjustment.

Design & Installation

The amplifier uses a compact aluminum extruded heatsink design with dual-fan cooling and real-time thermal sensing. Top-mounted controls provide access to gain, crossover, EQ, and setup functions after installation. Its detachable compression power terminal and harness-based signal and speaker connections support space-conscious mounting layouts.

Mount the amplifier on a solid surface with adequate airflow around the cooling system. Use 8 AWG power and ground wiring, a separately purchased 60-amp fuse, and 16 AWG speaker wire as specified. Configure the 2/4-channel input switch, crossover mode, and gain settings to match the connected source unit and speakers.