MB Quart RA1-710.5 5-Channel Class D Amplifier

The MB Quart RA1-710.5 is a five-channel car amplifier designed to power front and rear speakers along with a dedicated subwoofer from one chassis. It provides four full-range channels for a vehicle's main speakers and a separate fifth channel for low-frequency output. This configuration can simplify a complete audio-system upgrade where space and wiring organization matter.

For the full-range system, channels 1 through 4 provide 50 watts each at 4 ohms or 100 watts each at 2 ohms. The dedicated subwoofer channel provides 150 watts at 2 or 4 ohms, or up to 350 watts at 1 ohm. The fifth channel is the only channel rated for 1-ohm operation.

The amplifier uses Class D topology, with MB Quart identifying Class SQ operation for the full-range channels and Class Q1 operation for channel 5. Its full-range frequency response is rated from 10 Hz to 35 kHz, while the subwoofer channel is rated from 10 Hz to 250 Hz. Variable electronic crossovers allow the main speakers and subwoofer to be filtered for their intended frequency ranges.

Integrated setup controls include selectable full-range or high-pass filtering on channels 1 through 4, low-pass filtering on channel 5, a selectable 25 Hz subsonic filter, and 0 to 12 dB of bass boost. A wired bass remote is included for accessible adjustment of bass level from the cabin. The amplifier also supports DC signal sensing, which can turn it on when a signal is detected at its RCA inputs.

The RA1-710.5 is suited to universal vehicle applications and can be used in a system with an aftermarket source unit or an appropriately adapted factory-audio signal. Its 0.02 to 9V input-voltage range accommodates a broad range of source outputs. It is a practical choice for installers building a single-amplifier, five-channel system with controlled crossover settings and a dedicated subwoofer channel.

Key Features

• Five-Channel Layout: Powers four speakers plus one dedicated subwoofer channel.
• 1-Ohm Subwoofer Channel: Channel 5 delivers up to 350 watts at 1 ohm.
• Variable Crossovers: Filters speaker and subwoofer frequencies for system tuning.
• Wired Bass Remote: Allows convenient bass-level adjustment from the driver's seat.
• DC Signal Sense: Supports automatic turn-on from a detected input signal.
• Class D Design: Uses efficient Class D amplification across all five channels.

Design & Installation

The RA1-710.5 uses an aluminum heat sink to help dissipate heat during operation and a rugged MOSFET pulse-width-modulation power supply. Nickel-plated RCA inputs and heavy-duty connection points are designed for secure signal and wiring connections. The amplifier has a black finish and a compact unit footprint measuring 12.75 inches long, 6 inches wide, and 2.25 inches high.

Use 4 AWG power and ground cable with the amplifier's 4 AWG power terminals, and use up to 12 AWG speaker wire at the speaker terminals. An 80A external fuse is specified, and the amplifier should be mounted on a secure surface with adequate ventilation rather than upside down. For factory speaker-level signals, speaker-wire-to-RCA adapters are required; the included bass remote can be mounted within reach for subwoofer-level adjustment.