JL Audio MHD900/5 5-channel marine amplifier — 100 watts RMS x 4 + 500 watts RMS x 1

Features
Controls
Connections

Features

R.I.P.S. (Regulated, Intelligent Power Supply): The regulated power supply is stable over a range of impedance loads and input voltages.

• Regulated Power Supply: Regulated means the power supply adjusts its operation to maintain the amplifier's rated power output and low distortion operation over a wide range of vehicle voltages (11-14.5 volts). The result is power stability in real-world 12-volt systems.
• Intelligent Power Supply: The Intelligent portion of the R.I.P.S. System is a circuit that monitors output current to optimize the amplifier's output power over a wide range of load impedances (1.5Ω to 4Ω). The R.I.P.S. system detects the actual impedance being driven and adjusts output rail voltages to deliver optimum output. This process is automatic and accounts for the real impedance of the speakers, rather than relying on often inaccurate assumptions based on a speaker's rated impedance.

Specifications:

• Power Output:
  • Front/Rear:
    • 4Ω: 100 watts RMS x 4 (11-14.5 volts)
    • 1.5Ω-3Ω: 75 watts RMS x 4 (11-14.5 volts)
    • Bridged (8Ω): 200 watts RMS x 2 (11-14.5 volts)
    • Bridged (3Ω-6Ω): 150 watts RMS x 2 (11-14.5 volts)
  • Sub: 500 watts RMS x 1 (3Ω-6Ω and 11-14.5 volts)
• THD at rated power:
  • Front/Rear: <0.03% @ 4Ω
  • Sub: <0.05% @ 4Ω
• Signal to Noise Ratio:
  • At Rated Power: 108 dBA
  • At 1 Watt: 88 dBA
• Frequency Response:
  • Front/Rear: 12 Hz - 28 kHz (+0/-1 dB)
  • Sub: 12 Hz - 10 kHz (+0/-1 dB)
• Damping Factor:
  • Front/Rear:
    • 4Ω: >400 @ 50 Hz
    • 2Ω: >200 @ 50 Hz
  • Sub:
    • 4Ω: >800 @ 50 Hz
    • 2Ω: >400 @ 50 Hz

Class D with Single-Cycle Control: The MHD900/5 utilizes a patented Single Cycle Control Class D technology. This technology tracks the audio signal, comparing it to the real PWM waveform and then corrects it over 400,000 times per second; thus distortion-causing mechanisms can be tightly controlled to enable pristine amplification.

Compact/Efficient Design: The amplifier features an overall efficiency of 80% at ½ rated power, which leads to reductions in chassis size and current draw.

RealSink Heat Management With Rollback Protection: This amplifier employs RealSink heat management, with vertical cast alloy heat sink fins. The design of the heat sinks was refined through extensive finite-element analysis, resulting in amplifiers that stay cool under demanding conditions. If the amplifier ever reaches an unsafe temperature, the Advanced Rollback Protection circuit adjusts the power output until the amplifier cools down, without ever shutting your music down.

Differential-Balanced Inputs: The differential-balanced input architecture effectively controls noise and ensures 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 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 installation.

Mounting: The MHD series amps have three mounting options to choose from:

• Standard: The standard method of mounting requires removal of the four corner caps with the included 4mm Allen-wrench. Using the appropriate mounting screws (not included), you can then secure the amplifier in all four corners and re-install the corner caps.
• Mounting Feet: The included feet can be mounted to the bottom corners of the amp using the included machine screws. Including the feet, the with of the amp is 11.7" and the height is 2.145".
• Stacking: Using 136HDSTKIT Stack Kits (sold separately), multiple MHD amplifiers can be stacked on top of one another.

Controls

Control Panel Cover: The MHD900/5 features a control panel cover to protect and hide the amplifier's controls. When installed, the cover ensures that the amplifier's settings are not accidentally changed. The cover is pre-installed at the factory and must be removed to access the amplifier's controls. It's secured by a single 2.5mm Allen-head screw.

Gain: Because the amplifier's R.I.P.S. feature delivers a predictable maximum unclipped output, correctly setting the gain levels is easily done. You'll need a digital AC Voltmeter (1203320, sold separately) and audio files with 50 Hz and 1 kHz sine-wave test-tones recorded at 0 dB reference.

Input Level: The range of the input sensitivity dials has two settings. Low is typically used for line-level sources (200mV-2V) and High for speaker-level (800mV-8V).

Input Mode: Set the 3-position input mode switch based on the number of inputs connected to your source unit:

• 2-Channel: only a single pair of inputs is used, connected to the front input terminals; the rear and sub sections of the amp are also fed by the front input
• 4-Channel: the front and rear inputs are used, maintaining fader control; the sub section of the amp is fed by summing the two inputs
• 6-Channel: the front, rear, and sub terminals are connected to discrete signals from your source unit

Crossover Network: The front, rear, and sub sections of the amp have independent crossover controls:

• Front/Rear: The front and rear crossovers are High-Pass only.
  • Slope: The three position slope switch is set to Off (bypasses crossover for full range output), 12dB/octave (Butterworth), or 24dB/octave (Linkwitz-Riley).
  • Frequency: The crossover point is variable from 50-500 Hz (actually 53-508 Hz).
• Subwoofer: The subwoofer crossover is Low-Pass only.
  • Slope: The three position slope switch is set to Off (bypasses crossover), 12dB/octave (Butterworth), or 24dB/octave (Linkwitz-Riley).
  • Frequency: The crossover point is variable from 50-500 Hz (actually 53-508 Hz).
  • Infrasonic Filter: The Infrasonic Filter is a 24 dB/octave high-pass filter, with a fixed cutoff frequency of 30 Hz. This filter is designed to conserve amplifier power and protect subwoofer systems, without audibly degrading the sub-bass output. The Infrasonic filter can be turned off if you prefer.

Connections

Power/Ground/Turn-On: The amplifier features a Power/Ground/Turn-On plug that detaches from the amplifier to make connecting your power, ground, and remote turn-on lead wires more convenient. Once your connections are made, the plug connector simply snaps into the port on the amplifier.

• Power and Ground: The set-screw Power and Ground terminals accept up to 4-gauge wire. (4-gauge minimum is recommended.) A 4mm Allen-wrench is supplied for making the connections.
• Remote Turn-On: The set-screw turn-on terminal will accept up to 12-gauge wire. A 2.5mm Allen-wrench is supplied for making the connection.

Speaker Output: The amplifier also features three Speaker Output plugs (front, rear, and sub) that detach from the amplifier for easier speaker wire connection. Once your speaker wires are connected, the plugs simply snap into the ports on the amplifier. The set-screw terminals will accept up to 12-gauge wire. A 2.5mm Allen-wrench is supplied for making the connections.

Preamp Inputs: The amplifier features three pair of differential-balanced RCA jack inputs (front, rear, and sub), used for both preamp and speaker-level inputs (200mV-8V).

Remote Level Control: With the addition of the optional wired Remote Level Control (136HDRLC, sold separately), you can control the output level of the subwoofer channel. If desired, multiple MHD amplifiers can be controlled from a single HD-RLC controller using a simple phone line splitter and multiple phone cables (all sold separately).