Clean, flexible power for front/rear speakers or bridged sub channels—OEM-friendly and easy to tune
Looking to give your factory or aftermarket speakers the power (and clarity) they deserve—without a complicated install? The MB Quart Formula FA2-400.4 is a compact, 4-channel Class Q1 (Class D) car audio amplifier that delivers up to 100 W x4 @ 2 Ω or 200 W x2 bridged @ 4 Ω. It’s packed with MB Quart’s sound-quality engineering—Q-Stasis low-noise preamp and FLUID-FETS output devices—plus smart integration features like DC Signal Sense for easy tie-in to OEM head units. Whether you’re upgrading a daily driver or building a full system, this versatile amp brings your music to life with punchy mid-bass, clear vocals, and smooth highs. A smart, high-value upgrade to your automotive accessories lineup.
Key Features
- Flexible Power & Layout – 50 W x4 @ 4 Ω, 100 W x4 @ 2 Ω, or 200 W x2 bridged @ 4 Ω to run front/rear speakers—or bridge two channels for a compact sub.
- OEM-Friendly Integration – DC Signal Sense auto turn-on lets you connect via RCA signal from a factory radio—often no remote wire needed.
- Precision Onboard Tuning – Independent HPF/LPF 40–400 Hz (12 dB/oct) per pair, plus built-in bass control and 0.2–12 V input sensitivity for perfect gain matching.
- Engineered for Sound Quality – Class Q1 (Class D) topology with Q-Stasis preamp and hand-selected FLUID-FETS outputs keeps noise low and dynamics high.
Why it’s a great upgrade
The FA2-400.4 focuses on real-world clarity and control. The Rugged MOSFET PWM power supply feeds clean current to the output stage so the amp stays efficient and cool—even in tight installs. A heavy-duty heat sink wicks heat away from the MOSFETs, while nickel-plated RCA inputs and robust power/speaker terminals maintain solid, corrosion-resistant connections over time. With 10 Hz–22 kHz bandwidth and <0.5% THD, you get full-range musicality—acoustic detail, lively midrange, and tighter, more authoritative bass—at everyday listening levels and beyond.
Use it 4-channel for a front/rear upgrade, 3-channel (bridge one pair for a small sub + two full-range channels), or 2-channel bridged for higher-power stereo—this amp evolves with your system.
What’s included
- MB Quart FA2-400.4 amplifier
- Mounting hardware & quick-start documentation
Technical Specifications
- Class / Topology: Class Q1 (Class D), 4 channels
- Power (RMS): 50 W x4 @ 4 Ω, 100 W x4 @ 2 Ω, 200 W x2 bridged @ 4 Ω
- Max Power: 400 W
- Frequency Response: 10 Hz – 22 kHz
- THD: < 0.5%
- Input Sensitivity: 0.2 – 12 V
- Crossovers (12 dB/oct): HPF 40–400 Hz, LPF 40–400 Hz (variable electronic)
- Tone / EQ: Built-in bass control
- Inputs: RCA (nickel-plated); speaker-level compatible
- Auto Turn-On: DC Signal Sense (enable/disable)
- Power Terminals: 4 AWG (12 V/GND)
- Speaker Terminals: up to 12 AWG
- Fusing: 40 A external
- Protection / LEDs: Overload & speaker short diagnostics
- Warranty: 1 Year
- Fitment: Universal
Installation & setup tips
- Power first: Use quality 4 AWG power/ground. Fuse the power lead within 12–18 in of the battery (40 A total). Ground to bare, paint-free chassis.
- Integration: For factory radios, enable DC Signal Sense; run RCAs (or an appropriate adapter) from the source. Keep signal cables away from power to reduce noise.
- Crossover starting points:
- Door speakers / components: HPF 80–100 Hz for cleaner mids.
- Coaxials with solid mid-bass: HPF 60–80 Hz.
- Small sub (bridged pair): LPF 70–90 Hz; add bass boost sparingly.
- Gain staging: Set head-unit EQ flat and bass boost off. Raise gain until loud without distortion, then back off slightly.
- Ventilation: Mount with airflow around the heat sink; avoid enclosing the amp tightly behind panels without ventilation.
Terms to Know
- RMS vs. Max/Peak Power: RMS is the continuous power the amp can deliver (plan your system around it). Max/Peak is a brief burst.
- Bridging: Combining two channels into one more powerful channel—great for a compact sub. Observe the minimum 4-ohm bridged load.
- Ohm (Ω) / Impedance: The electrical load the amp “sees.” Lower Ω draws more power (if the amp supports it); higher Ω draws less.
- HPF / LPF (High-/Low-Pass Filters): HPF blocks deep bass from small speakers; LPF sends only bass to a sub—set where your speakers perform best.
- Input Sensitivity (0.2–12 V): Lets the amp match different signal levels from factory or aftermarket radios so you can set gain properly.
- THD (Total Harmonic Distortion): Lower THD generally means cleaner sound, especially at higher volumes.
The MB Quart FA2-400.4 Formula is a compact, bridgeable 4-channel amplifier that delivers real, usable power with excellent control—and it integrates easily with factory systems thanks to DC Signal Sense. With precise crossovers, low-noise circuitry, and robust thermal design, it’s a reliable way to elevate clarity, dynamics, and overall enjoyment in your vehicle—without overcomplicating your build.