JL Audio MX280/4 Compact marine/powersports 4-channel amplifier — 50 watts RMS x 4

Features
Controls
Connections

Features

4-Channel Amplifier: The JL Audio MX280/4 compact full range, 4-channel Class D marine amplifier is designed for the harsh marine environment. Its IPX7 water-resistance rating also makes it ideal for motorcycles, ATVs, or other utility vehicles. It can be used to drive four full-range speakers, or a couple of subwoofers.

NexD Switching Technology: The MX280/4 employs an advanced, high-speed Class D switching design called NexD that allows the amp to produce serious power without overtaxing the battery and charging system.

Amplifier Ratings:

• Rated Continuous (RMS) Power @ 14.4 V (<1% THD+N):
  • 50 watts RMS x 4 @ 4 Ω
  • 64 watts RMS x 4 @ 3 Ω
  • 70 watts RMS x 4 @ 2 Ω
  • 140 watts RMS x 2 @ 4 Ω bridged
• Rated Continuous (RMS) Power @ 12.5V (<1% THD+N):
  • 36 watts RMS x 4 @ 4 Ω
  • 47 watts RMS x 4 @ 3 Ω
  • 52 watts RMS x 2 @ 2 Ω
  • 100 watts RMS x 2 @ 4 Ω bridged

Input Section: The MX280/4's input section accepts a wide range of input voltage levels. It can accept a line-level signal from 250 mV to 4 Volts, or speaker-level signals from 750 mV to 15 Volts. The amp is equipped with Input Voltage switches for the front (1&2) and rear (3&4) channels that allows you to choose Low or High level input signals.

Protection Circuitry: The MX280/4's protection circuitry automatically shuts the amplifier down if thermal limits are exceeded, a short-circuit is detected in the speaker wiring, or if current levels are too high. The green Power LED and red Protect LED will indicate conditions by its on/off or flashing status.

Controls

Control Panel: The amplifier's control panel is located on the bottom of the amplifier. The removable cover is held in place by 4 Phillips-head screws, and features a rubber gasket that seals out moisture and dust. You will need a small flat screwdriver to set the five switches and four rotary dials. The Control Panel is divided into Front and Rear sections with the same controls in each section, plus a Channel Mode switch. The following controls are located in the Control Panel:

• Channel Mode: The 3-way Channel Mode switch lets you select 2-channel, 3-channel, or 4-channel operation:
  • 2-channel: In 2-channel mode you can run 2 bridged mono outputs or 4 stereo outputs without fading capability. In this mode, you can use the front inputs only.
  • 3-channel: 3-channel mode lets you 2 stereo front and 2 mono rear outputs, or 2 stereo front and a bridged mono output. Front inputs only are used in this mode.
  • 4-channel: If you select 4-channel mode, you can run 4 stereo outputs with fading capability. Both front and rear inputs are used in this mode. You can also run 2 bridged stereo outputs with the left input signal connected to both front inputs and the right input to both rear inputs.
• Independent Controls: The amplifier offers separate controls for the front channels and rear channels:
  • Input Voltage: You can select the type of input signal being used: High Level (speaker) or Low Level (line).
  • Input Sensitivity: The Input Sensitivity Control is a rotary dial that lets you match your source unit's output voltage to the input stage of the amplifier for maximum clean output.
  • Filter Mode Switch: The amp is equipped with switchable crossovers for each set of channels. You can set the filter to High-Pass (HP), Low-Pass (LP), or Off.
  • Filter Frequency: When the Filter Mode Switch is turned to HP or LP, you can set the cutoff frequency on the rotary dial. The filter is continuously variable from 35Hz to 300Hz, with detents at 80Hz and 135 Hz. The HP/LP filter has a slope of 12dB/Octave.

Connections

Wiring: The MX280/4's wiring is internally connected and exits the amp through a waterproof opening. The following connections can be found, each with 12" pigtails:

• Power: The power wire coming out of the amp is a single 10-gauge wire with an in-line fuse holder and 35A ATO fuse installed. JL Audio recommends a minimum of 8-gauge wiring for the power wiring. You will need to add another fuse to the power wire within 18" of the battery. A 35A fuse or circuit breaker is recommended.
• Ground: A 10-gauge ground wire is connected to the amplifier. A minimum of 8-gauge wiring is recommended for the ground wire. You may need a ground distribution block to splice the ground wires together.
• Remote Turn-On: A 16-gauge remote turn-on wire is connected to the amp. You should connect the turn-on lead to the remote turn-on output of your source unit. If the source unit does not have a dedicated remote turn-on output, the amp's turn-on lead can be connected to +12V via a switch that derives power from an ignition-switched circuit.     Note: The amp does not have an audio signal-sensing turn-on, so the remote turn-on lead must be connected.
• Signal Inputs: Four female RCA jacks are provided for the input signal--Left/Right Front and Left/Right Rear channels. If the source unit does not offer preamp level outputs, you can splice the speaker output wires to a pair of RCA plugs, or use the JL Audio XD-CLRAIC2-SW RCA-to-Speaker Wire Adapter. The amp's RCA connectors have waterproof caps.
• Speaker Outputs: Eight 16-gauge speaker wires are provided on the amplifier for connecting to the wiring to your speakers.