MB Quart RA1-1100.4 1100 Watt 4-Channel Amplifier Class D Car Stereo Amp

The RA1-1100.4 is a four-channel Class D car amplifier rated 1100W max, built to run a full set of speakers or a front stage plus a bridged subwoofer. Output is 4 x 150W at 4 ohms, 4 x 275W at 2 ohms, or 2 x 550W bridged mono at 4 ohms, which covers component fronts, coaxial rears, or a two-channel plus subwoofer arrangement from a single chassis. MB Quart calls the topology Class SQ, a Class D design paired with the Q-Stasis preamplifier stage that keeps distortion down as low voltage signal enters the amplifier. Measured performance backs it up: signal to noise above 101dB, THD below 0.09 percent, and frequency response from 10Hz to 35kHz. Variable electronic crossovers on both channel pairs switch between full range, high-pass, and low-pass from 50Hz to 250Hz at 12dB per octave, with 0 to 9dB of bass boost on tap. Input sensitivity spans 0.02 to 9V, so the amp accepts weak factory signal or a strong aftermarket preamp output. DC Signal Sense turns the amplifier on when signal appears at the RCA inputs, which removes the need to run a remote turn-on wire from the head unit and reduces factory system integration to adapting an RCA cable. FLUID-FETS output devices and an aluminum heat sink dissipate heat at lower impedance loads, and a MOSFET pulse width modulation power supply keeps current draw off the vehicle electrical system. Power terminals accept 4 AWG, speaker terminals 12 AWG, with a 90A external fuse.