Pioneer GM-DX874 4-Channel Class-D Car Amplifier

The Pioneer GM-DX874 is a bridgeable four-channel car amplifier designed to add clean, configurable power to an upgraded vehicle audio system. It can drive front and rear speakers independently, or be configured for two- or three-channel applications including a bridged subwoofer channel. This makes it a practical choice for listeners building a full-range system now or planning a staged upgrade.

Its continuous output is rated at 100 watts RMS per channel at 4 ohms, 150 watts RMS per channel at 2 ohms, and 300 watts RMS per bridged pair at 4 ohms. The wide 10 Hz to 50 kHz frequency response supports full-range speaker systems and high-resolution playback-capable sources. Class-D operation helps deliver this power from a compact chassis that is easier to place than many conventional amplifiers.

Separate variable high-pass and low-pass filtering lets the GM-DX874 be matched to speakers or subwoofers. Both crossover ranges adjust from 40 Hz to 500 Hz with a 12 dB/octave slope. This helps remove unnecessary low bass from smaller speakers or limit a subwoofer channel to low-frequency content.

The amplifier accepts RCA-level and speaker-level signals, allowing it to work with many aftermarket receivers as well as compatible factory-radio systems. Automatic signal sensing can turn the amplifier on when it detects a speaker-level input signal, though a system remote wire may be needed with some head units. A two-channel/four-channel input selector provides additional flexibility when planning system wiring.

For bass-focused channel B setups, the included wired bass boost remote adjusts 50 Hz boost from 0 dB to 18 dB. Gold-plated RCA connections, audio film capacitors, and a low-impedance output-filter coil support the amplifier's signal path. Built-in protection monitors abnormal conditions and can mute or shut down output if overheating, DC output, or a speaker-wire short is detected.

Key Features

• Four-Channel Class-D Amplification: Powers four speakers or supports bridged system configurations.
• 100W RMS Per Channel: Delivers rated continuous power at 4-ohm stereo loads.
• Variable HPF And LPF: Adjusts crossover points from 40 Hz to 500 Hz.
• High-Resolution Frequency Range: Extends from 10 Hz to 50 kHz.
• Speaker-Level Input: Connects to compatible factory-radio speaker outputs.
• Wired Bass Boost Remote: Adjusts channel B bass boost from 0 dB to 18 dB.

Design & Installation

The GM-DX874 uses a compact 252 mm × 60 mm × 215 mm chassis and weighs 2.5 kg without wiring leads. Its connection layout includes RCA inputs for channels A and B, an RCA pass-through output from channel A, block-style power and speaker terminals, and a POWER/PROTECT indicator. The amplifier incorporates gold-plated RCA connections and a protection system for temperature, DC-output, and short-circuit conditions.

Install it in a rigid, well-ventilated location with clearance above the chassis; do not cover it with carpet or a floor mat. The amplifier is intended for 12 V negative-ground vehicles and requires separately sold battery, ground, signal, and fuse components; Pioneer specifies an 80 A external battery-line fuse within 30 cm of the positive battery terminal. Use 8 AWG to 16 AWG speaker wire, match speaker impedance to the selected configuration, and set gain and crossover controls after wiring is complete.