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The JL Audio AP300/4 is a compact 4-channel Class-D amplifier from the AP marine series, designed to deliver up to 300 watts of clean, efficient power in a small, IP67-rated chassis. It can drive multiple pairs of full-range speakers or a mix of speakers and a subwoofer using its flexible bridging and onboard crossovers, making it ideal for small to mid-size boats and powersports builds where space and reliability are critical.
As the 4-channel model in the AP lineup, the AP300/4 is engineered to power up to four pairs of speakers or a combination of two pairs of speakers and a subwoofer using bridged channels. Its efficient Class-D topology delivers strong output while minimizing battery drain, a key advantage on marine and powersports electrical systems.
At 14.4 V and less than 1% THD, the AP300/4 is rated for 50 watts x 4 into 4 ohms or 75 watts x 4 into 2 ohms. For higher-output configurations, channels can be bridged to provide 150 watts x 2 into 4 ohms, giving you flexibility in how you allocate power between full-range zones and low-frequency channels.
A built-in LCD display gives you direct access to key amplifier settings at the amp itself, simplifying setup and adjustments during installation or service. For further optimization, the AP300/4 supports JL Audio’s Easy Tune feature when paired with a compatible Fusion® stereo that has built-in DSP and the Fusion® Audio app, allowing quick, profile-based setup to help protect speakers and maintain consistent system tuning.
Designed for harsh marine environments, the amplifier chassis carries an IP67 water and dust rating (excluding cables) and is ignition protected. Its compact footprint and low idle current draw make it easy to mount and integrate in tight compartments without putting unnecessary strain on the battery system.
| Model | AP300/4 |
| Channels | 4-channel |
| Amplifier Class | Class D |
| Operating Voltage | 9–16 VDC |
| Water/Dust Rating | IP67 (amplifier chassis, excluding cables) |
| Operating Temperature | 4° to 149°F (-20° to 65°C) |
| Rated Power @ 4 Ω (14.4 V) | 50 W x 4 / 150 W x 2 bridged (<1% THD) |
| Rated Power @ 2 Ω (14.4 V) | 75 W x 4 (<1% THD) |
| Frequency Response | 20 Hz – 20 kHz (+0, -1 dB) |
| Signal-to-Noise Ratio | >70 dB (A-weighted, 20 Hz–20 kHz, referred to 1 W) |
| Standby Current | <1 mA |
| Idle Current | Approximately 700–750 mA |
| Fuse Rating | 35 A (AFS, AGU, or MaxiFuse™ recommended) |
| Minimum Power/Ground Wire | 4 AWG copper wire |
| Protection Circuits | Input under/over voltage, over-temperature, output short circuit |
| Amplifier Dimensions (H x W x D) | 1.86" x 10.43" x 4.90" (47 x 265 x 125 mm) |
| High-Pass / Low-Pass Filters | Yes – full-range filters, user selectable |
| Filter Modes – Channels 1 & 2 | Off, High-pass (HP) or Low-pass (LP) |
| Filter Modes – Channels 3 & 4 | Off, High-pass (HP) or Low-pass (LP) |
| Filter Slope | 12 dB/octave (all channels) |
| Filter Frequency Range | 20 Hz – 500 Hz (HP or LP, channels 1–4) |
| HP Variable Crossover | Yes – 4-channel, 12 dB/octave |
| LP Variable Crossover | Yes – 4-channel, 20–500 Hz |
| Bass Boost EQ | 0 to +18 dB @ 37 Hz |
| Input Sensitivity | RCA inputs switchable: 200 mV–2 V RMS (Low), 800 mV–8 V RMS (High) |
| Input Impedance | 11 kΩ (High), 20 kΩ (Low) |
