JL Audio HD Series HD750/1

Features

Monoblock Full-Range Class-D Amplifier: The JL Audio HD750/1 is a very powerful and compact monoblock (single channel), full-range amplifier utilizing patented Single Cycle Control Class D technology. This technology delivers reference-grade sonic performance while requiring far less current from the vehicle’s electrical system than a conventional amplifier. Unlike most monoblock amplifiers, the HD750/1 is a full-range design so it can be used as a subwoofer amplifier or as a very powerful full-range or satellite amplifier using a second 750/1 to form a stereo pair.

Amplifier Rating: The JL Audio HD750/1 Class D monoblock, full-range amplifier is rated at 750 Watts RMS x 1-channel in 1.5 to 4-ohm at 20 to 20kHz with a signal-to-noise-ratio of 111 dB and a total harmonic distortion of 0.03% while receiving 11 to14.5 Volts.

High-Fidelity Class D (HD) With Single-Cycle Control: The JL Audio HD750/1 utilizes patented Single Cycle Control Class D technology for all channels. This technology delivers reference-grade sonic performance while requiring far less current from the vehicle’s electrical systems than a conventional amplifier. Single Cycle Control is a unique approach to controlling a full-range Class D amplifier. By tracking the audio signal, comparing it to the real PWM waveform, and then correcting it in each and every cycle (over 400,000 times per second), a multitude of distortion-causing mechanisms can be tightly controlled to enable pristine amplification. While there are certainly less expensive ways to make a full-range switching amplifier, no other Class D control system works faster or more accurately than Single Cycle Control.

Compact/Efficient Design: The JL Audio Class D amplifier on average is 13% smaller overall and over 1/2-inch shorter in height than most class-AB amplifiers. The HD750/1 features outstanding overall efficiency (80% at 1/2 rated power) which allows for huge power from a tiny chassis and is easy on your vehicle’s charging system, drawing 60% less current than a class AB design of equal power.

R.I.P.S. (Regulated, Intelligent Power Supply): R.I.P.S. stands for “Regulated, Intelligent Power Supply” and is a central feature of the JL Audio HD amplifier. The JL Audio R.I.P.S. System ensures consistent power delivery over a wide range of battery voltages and load impedances. This technology provides optimum power at any impedance level between 1.5 ohms to 4 ohms per channel and at any vehicle voltage level between 11V and 14.5V.

• Regulated Power Supply: “Regulated” means that the power supply adjusts its operation so as to maintain the amplifier’s rated power output and low distortion operation over a wide range of vehicle voltages (11V-14.5V ). This allows the JL Audio HD amplifier’s rail voltage and clean power output to remain stable in real-world car-audio systems, resulting in superior fidelity and stability.
• Intelligent Power Supply: The “Intelligent” portion of the R.I.P.S. System is a circuit that actually monitors output current to optimize the amplifier’s output power over a wide range of load impedances (1.5 ohms to 4 ohms per channel). The R.I.P.S. System detects the actual impedance being driven and adjusts output rail voltages to deliver optimum output. The entire process is seamless, automatic, and results in incredible dynamics for satellite channels and consistent power output for a wide range of subwoofer configurations. It also takes into account the real impedance of your car-audio system, rather than relying on often inaccurate assumptions based on a speaker’s rated impedance.

RealSink Heat Management With Rollback Protection: This JL Audio amplifier employs an advanced type of heat management, called RealSink. This feature takes advantage of convection and radiation effects to remove heat from the amplifier circuitry. For optimum cool performance, the vertical heat sinks located at the sides of the amplifier should be exposed to as large a volume of air as possible. If a JL Audio HD amplifier should ever reach an unsafe temperature, its unique Advanced Rollback Protection circuit also adjusts power until the amplifier cools down, without ever shutting your music 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 car audio installation. The JL Audio HD amplifier provides range switching on each of its inputs via the “Input Voltage” switch. This permits connection to a wide range of source voltages while retaining excellent sensitivity setting precision.

Note: You will need a speaker wire to RCA adaptor (136XDCLR2S, sold separately) to connect this amplifier to your headunit via speaker-level.

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

• Flashing Green: When the LED is flashing green, the amplifier is powering up and the audio output is muted.
• Constant Green: This LED lights green to indicate that the amplifier is turned on and operating normally.
• Constant Red: This Red LED lights to indicate that the amplifier has exceeded its safe operating temperature, putting the amplifier into a shelf-protection mode, which reduces the power output of the amplifier. The red light will shut off and the amplifier will return to normal, full-power operating mode if the heat sink temperature drops back to a safe level.
• Constant Yellow: This amber LED lights to indicate that the impedance of the speaker load connected to the amplifier is lower than the optimum impedance load range for the amplifier. When this light is on, a protection circuit engages and reduces the power output of the amplifier. The amber indicator will also light when a short-circuit is detected in the speaker wiring.
• Alternating Red/Green: The LED alternated between Red and Green to indicate that the amplifier is experiencing a fault that may require service of the amplifier, its wiring, or the vehicle’s operating system. Audio is muted when this fault occurs.

Note: There is only one condition that will shut down the HD750/1 completely and that is if the battery voltage of your vehicle drops below 10 volts.

Mounting Options: The HD750/1 has two mounting options to choose from during installation.

• Standard Mounting: The standard method of mounting requires removal of the four corner caps with the 3/16-nch he-wrench included with the amplifier. Using the appropriate mounting screws (not included), you can then secure the amplifier in all four corners and replace the corner caps.
• Lateral Mounting Feet: Lateral Mounting Feet are also included with the HD750/1 to provide an alternative mounting option. Each mounting foot should be attached to the bottom of the amplifier by screwing the provided bolts into the bottom of the amplifier and up into the corner cap with the supplied 1/8-inch hex-wrench. Then, using the appropriate mounting screws (not included), you can secure the amplifier by its four lateral mounting feet.

Controls

Control Panel Cover: The HD750/1 features a Control Panel Security Cover which protects and hides the amplifier’s controls. When installed, the cover ensures that the amplifier’s settings are not accidentally changed while creating a clean aesthetic look for the amplifier and your installation. The control panel security cover is pre-installed at the factory and must be temporarily removed for access to the amplifier’s controls. The security cover is secured by a single 2.5mm hex-head screw.

Simplified Gain Setting: The amplifier’s R.I.P.S. feature also allows for easy gain setup. Because the amplifier will always deliver the same amount of power within its operational range of impedances and supply voltages, the maximum, unclipped output is very predictable. This makes setting the gain level of the amplifier via the input sensitivity control very simple. All you need is Digital AC Voltmeter (142TK12V, sold separately) and a Test CD Disc (503CD104, sold separately) 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).

Flexible Input Section And Active Crossover Network: The JL Audio HD amplifier provides a flexible input section and a comprehensive crossover network to fine-tune your system effectively and accurately. The variable filter design employed in the JL Audio HD amplifier crossover sections allows you to seamlessly switch slopes, easily change filter frequencies, and address what frequencies the preamp outputs will pass. The HD750/1 offers the following independent crossover adjustments behind a removable cover plate.

• Filter Mode: The amplifier features a Full-Range, variable Low-Pass, or variable High-Pass filter mode for the amplifier’s preamp input section.
• Switchable Slope on all filters: 12dB/octave Butterworth or 24dB/octave Linkwitz-Riley alignments allowing for more precise integration of subwoofer and speaker channels.
• Variable Frequency: Fully-variable frequency selection from 50-500 Hz for high-pass or low-pass crossover.
• Infrasonic Filter: The Infrasonic Filter is a 24 d/b/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.

Output Polarity Control: Depending on the distance relationship of the mid-bass speakers and the subwoofers in your system, it can be desirable to reverse the polarity of the subwoofer system in order to produce a better transition between subwoofer and midbass speaker output. The amplifier’s Output Polarity switch allows you to quickly perform this polarity inversion.

Connections

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

• Power and Ground: The JL Audio amplifier’s set-screw Power and Ground connections found on the detachable Power/Ground/Turn-on plug are designed to accept 8 to 4 AWG power wire. A 2.5mm hex-wrench is supplied for making connections.
• Remote Turn-On: The JL Audio HD amplifier’s set-screw turn-on lead found on the Power/Ground/Turn-on plug will accept 18 to 8 AWG wire. The same 2.5mm hex-wrench is supplied for making a connection.

Note: The Amplifier is not equipped with a fuse. An external 60-amp AFS, AGU, or MAXI fuse (not included) must be installed on the power wire. If a wiring kit is used which includes a fuse with a value other than 60-amps, the original should be replaced with a 60-amp fuse.

Speaker Output Plugs: The amplifier features one Speaker Output plug which detaches from the amplifier for easier speaker wire connection. Once your speaker wires are connected to these plugs, they simply push into the amplifier. The Speaker Output plug features four set-screw terminals for an easy parallel subwoofer connection. The HD750/1 amplifier’s four set-screw speaker terminals found on the Speaker Output plug will accept 16 to 8 AWG speaker wire. A 2.0mm hex-wrench is supplied for making connections.

Preamp Inputs: The amplifier features one set of differential-balanced RCA jack inputs. The amplifier features a dedicated Input Sensitivity gain control for these inputs. These controls are designed to match the input sensitivity of the HD750/1 to the specific signal source that is feeding it. The amplifier’s input level can be set to Low (200mV-2V RMS) when connecting the amplifier to a low-level preamp signal or set to High (800mV-8V RMS) when connecting the amplifier to a high-level speaker signal.

Preamp Outputs: The HD750/1 incorporates a pass-through preamp output sections so that additional amplifiers can easily be connected to the same signal(s) feeding the HD750/1. These preamp output signals are buffered to prevent noise and are always preamp level, regardless of the level of signals feeding the HD750/1’s inputs.

Remote Level Control: The amplifier features a standard telephone connector for adding an optional wired remote level control. With the addition of the optional wired Remote Level Control (136HDRLC, sold separately), you can control the volume of the HD750/1 form the front of your vehicle. This is useful for subwoofer level control. If desired, multiple HD amplifiers can be controlled from a single HD-RLC controller using a simple phone line splitter and multiple phone cables (all sold separately).

Note: All inputs and outputs are located on the rear side of the amplifier to make installation of the amplifier simple and neat.