Marine amplifier AP300/4

The JL Audio AP300/4 amplifier is a compact Class D 4-channel model designed specifically for marine environments and motorized sports. It delivers a total power output of 300 watts RMS, making it a robust solution for enhancing your onboard audio system.

The AP300/4 amplifier delivers the following power outputs:

50 W x 4 at 4 ohms
75 W x 4 at 2 ohms
In bridged mode, it can deliver 150 W x 2 at 4 ohms.

Yes, this amplifier is designed to be water-resistant. However, it should not be submerged or exposed to high-pressure water jets, as exposure to water pressures exceeding its rating may damage the device.

The AP300/4 amplifier has several settings to fine-tune sound:

GAIN (Input sensitivity): Adjusts the output voltage of the source unit to the amplifier inputs, from 1 to 11.
HPF (High-pass filter): Attenuates frequencies below the selected cutoff frequency, from 20 Hz to 500 Hz, at a rate of 12 dB per octave.
LPF (Low-pass filter): Attenuates frequencies above the selected cutoff frequency, from 20 Hz to 500 Hz, at a rate of 12 dB per octave.
B.B (Bass Boost): Equalizer that increases the range centered at 37 Hz by 0 to +18 dB.

The Easy Tune mode automatically adjusts amplifier settings for systems with DSP profile capabilities or standalone signal processors. When this mode is enabled, the amplifier buttons are locked and inoperative. To activate or deactivate, hold the MODE / CH button for 15 seconds. The screen will display "Easy Tune" for 60 seconds upon activation.

Yes, you can change the temperature unit displayed. When the default display is active, press the up or down arrow button to toggle between temperature readings in Fahrenheit (default) and Celsius. Then hold the MODE/CH button to save your selection.

To check the current firmware version of your amplifier, press and hold the MODE / CH and up arrow buttons simultaneously for three seconds. The amplifier will then display the firmware version.

For installation of the JL Audio AP300/4 amplifier, you will need the following tools:

A Phillips screwdriverA drillA 3 mm (1/8 in) drill bit

The amplifier must be installed in a dry, well-ventilated location that does not interfere with the vessel’s factory-installed systems. It must be mounted securely to prevent damage or injury under harsh conditions. Ensure all wiring is kept clear of moving parts and sharp edges.

During installation, it is critical to follow these precautions:

Disconnect the vessel's audio system power before starting.Always wear safety glasses, hearing protection, and a dust mask when drilling, cutting, or sanding.Always check what is on the other side of the surface before drilling or cutting to avoid damaging the vessel.

The amplifier power wiring must be done as follows:

The positive wire (+12V DC, red) must run through an inline fuse or circuit breaker (not included) as close as possible to the power source.Connect the ground wire (black) to the system ground.Connect the remote control wire (blue) to the power source.The amplifier must only be used with 12-volt negative-ground electrical systems.

To mount the amplifier:

Identify the four M4 x 35 mm screws included with the device. Place the amplifier in the mounting location and mark the pilot hole positions. Remove the amplifier from the mounting location. Using a 3 mm (1/8 in) drill bit, drill four pilot holes in the mounting surface. Secure the amplifier to the mounting surface using the four screws.

To manually adjust input sensitivity (GAIN):

Disconnect the speakers from the amplifier's output connectors. Disable all audio processing (bass/treble, loudness, equalizer, etc.) on both the source unit and the amplifier. Set all fader controls to the center position and the subwoofer level control to 3/4 of maximum, if used. Set all GAIN controls to "1". Set the source unit volume to 3/4 of maximum. Determine the target AC voltage for input sensitivity adjustment based on the nominal impedance of the speaker system. Connect an AC voltmeter to the amplifier's speaker output terminals. While playing a suitable sine wave (1 kHz for full-range channels) at 3/4 of the source unit volume, adjust the GAIN control until the AC voltage reaches the target. Reconnect the speakers after adjustment. Do not increase GAIN settings beyond the established maximum level to avoid distortion and speaker damage. Re-adjust GAIN settings if an equalizer boost is enabled after this procedure.

Yes, after installing an audio system, it is recommended to run the speakers and subwoofers connected at low to moderate volumes during the first few hours of use. This helps improve overall sound by gradually breaking in the moving components of new speakers, such as the cone, spider, and surround.

Yes, the JL Audio AP300/4 amplifier is designed for use only with 12-volt negative-ground electrical systems.

The AP300/4 amplifier supports the following minimum impedances for speaker outputs:

In stereo mode: the minimum impedance for each speaker output is 2 ohms.In bridged mode: the minimum impedance for each speaker output is 4 ohms.

The AP300/4 amplifier supports an input sensitivity range of 200 mV to 8 V RMS. You can select between two sensitivity ranges: the LOW range (default) is 200 mV to 2 V RMS, and the HIGH range is 800 mV to 8 V RMS.

Yes, the JL Audio AP300/4 amplifier includes an Easy Tune mode that automatically adjusts the amplifier settings for use with car radios equipped with DSP profile capabilities or systems with standalone signal processors.