MB Quart PA1-800.4 4-Channel Amplifier — Open Box

MB Quart PA1-800.4 Premium Pro 4-Channel Amplifier — Open Box

The PA1-800.4 is the compact four-channel option in MB Quart's Premium Pro lineup. It makes sense when you want enough power for a normal amplified front/rear system or a pair of compatible bridged loads, but stepping all the way up to the PA1-2400.4 would add power, current demand, and cost that the speakers do not actually need.

MB Quart publishes 100 watts × 4 at 4 ohms and 200 watts × 4 at 2 ohms, with the option to bridge the amplifier to 400 watts × 2 at 4 ohms. That is a useful range for quality door speakers, passive component sets, rear speakers, or two higher-power 4-ohm drivers. The 5.81 × 4.45 × 2.0-inch chassis is also easy to package when the amplifier rack has to share space with a DSP, subwoofer amplifier, distribution, or factory modules.

PA1-800.4 or PA1-2400.4?

Choose the PA1-800.4 when roughly 100 watts per channel at 4 ohms or 200 watts per channel at 2 ohms is enough for the speakers being used. Choose the PA1-2400.4 when the build is centered around high-output pro-audio speakers, heavier midbass, or another load that genuinely needs several hundred watts per channel. Bigger is not automatically better if the extra power requires more electrical support and never gets used.

The electrical requirements show the difference clearly. MB Quart specifies 8 AWG power and ground connections with an external 80-amp fuse for the PA1-800.4. The PA1-2400.4 moves to 4 AWG and a 250-amp external fuse. Either amplifier still needs proper wiring, grounding, fusing, and airflow; the smaller PA1 simply fits a different power class.

How We Would Use It

For a four-speaker system, run one channel per speaker and set the high-pass filters to protect the drivers from low-frequency content they should not be reproducing. For a two-channel application, the amplifier can be bridged to two 4-ohm loads for up to 400 watts per channel. Do not treat the bridged rating as a four-channel number, and do not wire a 2-ohm bridged load when MB Quart only publishes bridged power at 4 ohms.

Both channel pairs have switchable high-pass, full-range, and low-pass operation with 45 Hz–850 Hz filter adjustment. That gives the amp useful basic crossover control for door speakers and midbass, but a complex active front stage still belongs on a DSP when it needs crossover points above 850 Hz, time alignment, detailed EQ, or more precise filter slopes.

Factory Signal Considerations

High-level speaker inputs are built in, which can simplify connection to some factory sources. That does not mean every factory radio can be connected directly and called finished. If the OEM system has factory EQ, bass roll-off, all-pass filters, active crossovers, or channels that need to be summed, the signal needs to be evaluated and integrated correctly before the amplifier is installed.

Open-Box Closeout

This listing is for the open-box PA1-800.4 closeout, not a standard new-retail listing. Buy this version when the amplifier itself is the right match for the system and the open-box condition makes sense for the budget. This is a final-sale closeout item, so the system planning should be done before purchase rather than using the lower price as the reason to oversize or mismatch the amplifier.

Manufacturer Specifications

Manufacturer Features

• Low-noise preamplifier circuit
• Two pairs of nickel-plated RCA inputs
• High-level speaker input capability
• PWM MOSFET power supply
• Extruded aluminum heat sink with built-in fan cooling
• Thermal, overload, DC and speaker-short protection diagnostics