JL Audio M500/3 3-channel marine amplifier — 75 watts x 2 at 4 ohms + 300 watts x 1 at 2 ohms

Features
Controls
Connections

Features

3-Channel Full-Range Amplifier: The JL Audio M500/3 is a 3-channel, class-D marine amplifier, designed to power two channels full-range, plus a subwoofer. The amplifier is stable to 2Ω and channels 1&2 can be bridged.

Marine Amplifier: The JL Audio M-series marine amplifiers are specifically designed for marine applications. These amps are not waterproof, however, and should not be mounted where they are likely to get wet.

Specifications:

• Power Output:
  • Full Range Channels: measured at 14.4 volts, 20 Hz - 20 kHz, with <1% THD+N
    • 4Ω: 75 watts RMS x 2-channels
    • 2Ω: 100 watts RMS x 2-channels
    • Bridged: 200 watts RMS x 1-channel (into 4Ω)
  • Subwoofer Channel: measured at 14.4 volts, 20-1,000 Hz, with <1% THD+N
    • 4Ω: 180 watts RMS x 1-channel
    • 3Ω: 240 watts x RMS 1-channel
    • 2Ω: 300 watts x RMS 1-channel
• Signal to Noise Ratio:
  • Full Range Channels: 84 dBA at 1 watt (104 dB at rated power)
  • Subwoofer Channel: 83 dBA at 1 watt (103 dB at rated power)

NexD Class D Technology: NexD is a state-of-the-art switching amplifier design that combines exceptional audio quality with excellent efficiency and less complexity. This results in an affordable compact amplification with exceptional audio quality and unsurpassed total efficiency.

Advanced Rollback Protection: The M-Series amplifiers employ advanced thermal and low-impedance protection to virtually eliminate amplifier shut-down events. Should the amp ever overheat, its intelligent, unregulated power supply reacts by limiting available peak voltage until it returns to a safe temperature range. Likewise, if an impedance lower than optimal for the amplifier is present at the outputs, the M-series amplifier will roll back peak voltage to protect itself without shutting down.

Differential-Balanced Inputs: The JL Audio amplifier features differential-balanced input architecture to effectively control noise and ensure compatibility with a wide variety of source units, including many OEM systems. Without resorting to line output converters, you can directly connect most OEM source units to the JL Audio amplifier without creating any noise or compatibility issues. Unlike conventional single-ended inputs, the differential-balanced design does not connect one side of the audio signal to chassis ground. This eliminates any voltage sensitivity between one input terminal and ground and greatly reduces the incidence of alternator whine in a typical 12-volt audio installation.

Protection Circuitry With Status Indicator Lights: There is a single multi-color LED on the top panel of the amplifier to indicate the amplifier's operating status:

• Flashing Green: the amplifier is powering up and audio output is muted
• Constant Green: indicates the amplifier is turned on and operating normally
• Constant Red: indicates the amplifier has exceeded its safe operating temperature, putting the amplifier into a self-protection mode, which reduces the power output of the amplifier; the red light will turn off and the amplifier will return to normal, full-power operating mode if the heat sink temperature drops back to a safe level
• Constant Amber (Yellow): indicates an over-current condition has occurred, accompanied by a muting of the amplifier's output; over-current condition can be caused by a speaker impedance lower than the optimum range or a short-circuit in the speaker wiring
• LED Off: if the battery voltage or remote turn-on voltage drops below 10 volts the amp will shut down completely; the amplifier will turn back on when voltage climbs back above 11 volts

Cooling System: The outer shell of the amplifier is designed to remove heat from the amplifier circuitry. For optimum cooling performance, this outer shell should be exposed to as large a volume of air as possible. Enclosing the amplifier in a small, poorly ventilated chamber can lead to excessive heat build-up and degraded performance.

Controls

Control Panel Cover: The M500/3 features a control panel cover with a rubber gasket that protects and hides the amplifier's controls. The cover is pre-installed at the factory and must be temporarily removed for access the amplifier's controls. The security cover is secured by two 2.5mm Allen-head screws.

Gain: The M Series amplifier instructions describe setting the gain levels accurately using a digital AC Voltmeter and a test disc with a sine-wave test-tone recorded at 0 dB reference level in the frequency range to be amplified for that set of channels (50 Hz for subwoofer channels, 1 kHz for a midrange application).

Input Mode: This switch allows operation of all three amplifier channels with only one pair of input signals (2Ch), or with discrete front and subwoofer signal inputs (4Ch).

Remote Level Mode: You can assign the operation of an optional HD-RLC wired remote (item number 136HDRLC, sold separately) to all three channels (ALL), or just the subwoofer channel (SUB).

Preouts From: The pass-through preamp outputs can be configured three different ways:

• 1&2: The preamp output delivers the same signal that is connected to the channel 1&2 inputs.
• Sub: The preamp output delivers the same signal that is connected to the subwoofer inputs.
• Sum: The preamp output delivers a summed stereo signal, combining the channel 1&2 and subwoofer inputs.

Crossover Network: The channel 1&2 and subwoofer channel have independent crossovers and controls:

• Channels 1&2:
  • HP Filter Mode: select either high-pass (HP) or full-range (Off) operation
  • Frequency: although labeled 50 Hz to 500 Hz, the crossover point range is actually 49 Hz to 483 Hz
• Subwoofer Channel:
  • LP Filter Mode: select Off (full-range, the full range of the subwoofer amp that is, 10-1,000 Hz, useful when using an outboard crossover), 12 dB/octave slope, or 24 dB/octave slope
  • Frequency: although labeled 50 Hz to 500 Hz, the crossover point range is actually 49 Hz to 483 Hz

Connections

Power/Ground/Turn-On Terminals: The amplifier features screw clamp terminals for the power, ground, and remote turn-on connections:

• Power and Ground: accept up to 4-gauge wire (recommended); 2.5mm Allen wrench supplied for making connections
• Remote Turn-On: accepts 18 to 12-gauge wire; the same 2.5mm Allen wrench is supplied for making connection

Speaker Output Terminals: The four pair of screw clamp speaker terminals will accept 16 to 8-gauge speaker wire. There are two pair of subwoofer outputs, internally shorted together, making it easy to connect two subwoofers (minimum total impedance 2Ω). The included 2.5mm Allen wrench is used for making connections.

Preamp Inputs: The amplifier features two pair of differential balanced RCA jack inputs with independent input sensitivity controls for channels 1&2 and the subwoofer channel.

Preamp Outputs: The M500/3 has a pass-through preamp output, so an additional amplifier can be easily added to the system. The preamp output signal is not affected by the amp's crossover. You can select which channels feed the preamp outputs: 1&2, Sub, or Summed.

Remote Level Control: The amplifier features an RJ-14 port for adding an optional wired remote level control, allowing adjustment of the output level of all three channels simultaneously, or just the subwoofer channel. If desired, multiple M-series amplifiers can be controlled from a single HD-RLC controller using a simple phone line splitter and multiple phone cables (all sold separately).