MB Quart RA1-280.4 Reference Series 280W 4-Channel Class D Car Amplifier

The MB Quart RA1-280.4 is a 280-watt, four-channel car audio amplifier from MB Quart's Reference Series, engineered to deliver exceptional sound clarity and power efficiency. Rated at 50 watts RMS x 4 at 4 ohms and 70 watts RMS x 4 at 2 ohms, this compact Class D amp punches well above its size, giving your speakers the clean, dynamic output they deserve.

Powered by MB Quart's proprietary Q-Stasis (Class SQ) circuitry, the RA1-280.4 goes beyond standard Class D performance by improving sonic accuracy and musical clarity. The FLUID-FET output devices are precision-selected to efficiently produce power while mimicking the warmth and detail of high-end home audio amplifiers.

Key Features:

• 50W RMS x 4 @ 4 ohms / 70W RMS x 4 @ 2 ohms / 140W x 2 bridged
• Class D / Class SQ topology with Q-Stasis pre-amplifier stage for low-distortion signal handling
• FLUID-FET output devices for efficient, high-fidelity power delivery
• DC Sensing / speaker-level inputs with signal-sensing auto turn-on — integrates easily with factory OEM systems
• Variable high-pass and low-pass crossover filters (50–250 Hz, 12 dB/octave)
• Variable bass boost: 0–9 dB
• Subsonic filter for subwoofer protection
• Remote bass knob included for front-seat subwoofer level control
• Configurable as 4-channel, 3-channel, or 2-channel operation
• Nickel-plated, hex-screw terminals — erosion-resistant and high-temperature rated
• Aluminum heat sink for efficient thermal management at low impedance loads
• Rugged MOSFET PWM power supply for efficient, low-drain operation
• Recommended wiring: 4-gauge power and ground, 40A in-line fuse (not included)

Its flexible design and OEM integration-ready inputs make it a versatile solution for factory system upgrades and custom aftermarket builds alike.