MB Quart FA2-900.5 5-Channel Car Audio Amplifier

The MB Quart FA2-900.5 is a compact five-channel car audio amplifier built to power four full-range speakers and one subwoofer from a single chassis. It is intended for vehicle audio upgrades that need dedicated amplification for the main cabin speakers plus low-frequency support. Its five-channel layout can simplify a system compared with using separate full-range and mono amplifiers.

Channels 1 through 4 deliver up to 100 watts RMS each at 2 ohms or 50 watts RMS each at 4 ohms. The dedicated fifth channel supplies 200 watts RMS at 4 ohms, 250 watts RMS at 2 ohms, or 500 watts RMS at 1 ohm. Only channel 5 is specified as 1-ohm stable, making correct speaker and subwoofer load matching important.

The FA2-900.5 uses MB Quart's Class Q1 Class D topology with FLUID-FETS output devices and a rugged MOSFET pulse-width-modulation power supply. Its Q-Stasis pre-amplifier stage is designed to handle low-voltage source signals with minimal distortion. A heavy-duty heat sink helps move heat away from the amplifier's internal MOSFETs during operation.

Variable electronic crossovers let the amplifier be configured for separate speaker and subwoofer duties. The high-pass crossover adjusts from 40Hz to 400Hz, while the low-pass crossover adjusts from 40Hz to 300Hz. A 10Hz to 40Hz subsonic filter and 0dB to 12dB bass boost provide additional low-frequency adjustment.

This amplifier supports speaker-level audio inputs and uses nickel-plated RCA inputs for low-level connections. DC Signal Sense can automatically turn the amplifier on when it detects a signal at the RCA inputs, reducing the need for a separate remote turn-on lead in compatible installations. A wired bass remote is included for making bass-level adjustments from the driver's seat.

Key Features

• Five-Channel Configuration: Powers four full-range channels and one dedicated subwoofer channel from one amplifier.
• 1-Ohm Subwoofer Channel: Channel 5 is rated for 500 watts RMS at 1 ohm.
• Variable Electronic Crossovers: Helps route appropriate frequency ranges to speakers and the subwoofer.
• DC Signal Sense: Enables automatic turn-on from a detected RCA input signal.
• Wired Bass Remote: Lets the driver make convenient bass-level adjustments from the listening position.
• Protection Diagnostics: Illuminated indicators monitor overload and speaker-short protection conditions.

Design & Installation

The FA2-900.5 has a black compact chassis with a heavy-duty heat sink, nickel-plated RCA inputs, and heavy-duty power, ground, and speaker connections. MB Quart specifies a Class D design, FLUID-FETS output devices, and a MOSFET PWM power supply. The amplifier measures 15.0 inches long, 5.82 inches wide, and 2.2 inches high.

For installation, use the amplifier with properly matched speaker and subwoofer impedances, keeping the 1-ohm load limited to channel 5. The power and ground terminals accept up to 4 AWG cable, while speaker terminals accept up to 12 AWG cable; MB Quart specifies external 100A fusing. Mount the amplifier to a secure surface with adequate ventilation, then set crossover, subsonic-filter, gain, and bass settings to suit the connected speakers and source unit.