JL Audio MX500/4 - User Manual

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Thank you for purchasing a JL Audio amplifier for

your sound system.

Your amplifier has been designed and manufactured to exacting

standards in order to ensure years of musical enjoyment. For maximum

performance, we highly recommend that you have

your new amplifier installed by an authorized JL Audio dealer. Your

authorized dealer has the training, expertise and installation equipment

to ensure optimum performance from this product. Should you

decide to install the amplifier yourself, please take the time

to read this manual thoroughly to familiarize yourself

with its installation requirements and setup procedures.

If you have any questions regarding the instructions in this

manual or any aspect of your amplifier’s operation, please contact your

authorized JL Audio dealer for assistance. If you need further assistance,

please call the JL Audio Technical Support Department

at technical@jlaudio.com or call (954) 443–1100 during business hours.

OWNER’S MANUAL

500W Full-Range 4-Channel Class D Amplier

What’s Included

(1) Amplifier

(4) Stainless steel mounting screws

(1) User manual

Product Description

This is a four-channel, full-range audio amplifier utilizing Class D technology for

all channels.

Installation Applications

This amplifier is designed for operation with 12 volt, negative-ground electrical

systems. Using this product in systems with positive ground and/or voltages

other than 12V may result in damage to the product and will void the warranty.

This product is not certified or approved for use in aircraft.

Safety Considerations

• Whenever possible, mount the amplifier in a dry, well-ventilated location

that does not interfere with other factory installed electronic devices. If a dry

environment is not available, a location that is not exposed to heavy splashing

may be used.

• While this amplifier is designed to be water-resistant, it should never be

submerged under water or subjected to high-pressure water spray.

Do not install where it will be directly exposed to the elements.

• Do not mount the amplifier in the engine compartment or in any areas of

extreme heat.

• Securely mount the amplifier so that it does not come loose in the

event of a collision/sudden jolt or as a result of repeated vibrations during

normal operation.

• Check before drilling to make sure that you will not be drilling into an exterior

panel/hull, fuel tank, gas/brake line, wiring harness, or other vital system.

• Do not run system wiring outside or underneath the vehicle/vessel. This is an

extremely dangerous practice, which can result in severe damage/injury.

• Protect all system wires from sharp edges (metal, fiberglass, etc.) by

carefully routing them, tying them down and using grommets and loom

where appropriate.

• Secure all wiring as needed, using cable ties or wire clamps to protect them

from moving parts and sharp edges.

IPX7 Water Resistance Rating

This product has been tested to withstand immersion in water, up to 1 meter

(3.28 ft.) deep, for up to 30 minutes (with control panel cover properly installed).

Note - while designed to be water resistant, this product should never be

submerged under water for prolonged periods or subjected to activity that

creates pressure on it that exceeds its depth rating.

Installation Procedure/Connections

1. Disconnect the NEGATIVE battery post connection and secure the discon-

nected cable to prevent accidental reconnection during installation. This is

an essential safety precaution during installation!

2. Connect the RED power lead to the positive (+12V) battery post. 4 AWG is

the minimum power wire size for this amplifier.

3. An appropriate fuse (sold separately), such as the JL Audio Water-Resistant

Master MAXI™ Fuse Block (XD-MFBW-MAXI), at the main power wire(s) to

the amplifier(s) is vital for vehicle/vessel safety. This fuse must be installed

within 18 inches (45 cm) of the positive battery post connection. If this is

the only device connected to this main wire, use a 50A fuse. Do not install

the fuse until the power wire has been securely connected to the amplifier.

4. Connect the BLACK negative ground lead to a clean, solid metal grounding

point near the amplifier. This can be to metal chassis ground, if available. If

no metal chassis ground is available, it may be necessary to make this con-

nection to the NEGATIVE battery post. 4 AWG is the minimum ground wire

size for this amplifier. All ground connections (source unit and amplifi-

ers) should be made at the same location.

5. Connect the BLUE remote turn-on lead to the source unit’s positive (+12V)

remote turn-on output. If your source unit does not have a dedicated

remote turn-on output, the amplifier’s turn-on lead can be connected to

+12V via a switch that derives power from an ignition-switched circuit.

6. Signal Input (Low-Level): Connect the amplifier’s RCA input jacks to the

source unit’s preamp level output jacks.

7. Signal Input (Hi-Level): If your source unit does not offer preamp level signal

outputs, you can splice the speaker output wires of the source unit onto a

pair of RCA plugs for each input pair or use the JL Audio ECS Speaker Wire

to RCA adaptor (XD-CLRAIC2-SW). Make sure to observe correct polarity in

making “Hi-Level Input” connections. Failure to do so will result in a loss of

signal (poor performance).

8. Connect the speaker output leads to the corresponding speaker wires.

9. Make necessary adjustments to the filter controls and input sensitivity.

WARNING! Failure to make safe, tight, high-integrity power connections

can result in fire and extensive damage!

Control Setting Mode / Function

Channel Mode

2CH

#1) 4 Stereo Outputs (non-fading)

Use Front

Inputs Only

#2) 2 Bridged Mono Outputs

3CH

#1) 2 Stereo Front + 2 Mono Rear Outputs

Use Front

Inputs Only

#2) 2 Stereo Front + 1 Bridged Mono Rear Output

4CH

#1) 4 Stereo Outputs (fading) Use Front and Rear Inputs

#2) 2 Bridged Stereo Outputs

Left to Both

Front Inputs

Right to Both

Rear Inputs

Front

Rear

Input

Voltage

Low RCA/Preamp Level Range (250 mV - 4 V)

High RCA/Preamp or Speaker Level Range (750 mV - 15 V)

Filter

Mode

Off Full-Range Operation of Input Signals

(High-Pass) Configures Filter to Attenuate Frequencies BELOW

the Selected Filter Frequency

(Low-Pass) Configures Filter to Attenuate Frequencies ABOVE

the Selected Filter Frequency

Filter

Freq.

Variable

Adjusts the filter cutoff frequency of the selected Filter Mode,

variable from 35-300 Hz, 12 dB/Octave

Input

Sens.

Variable

Adjusts the input stage of each pair of amplifier channels to

match the source unit’s output voltage for maximum clean

output (refer to Appendix A)

Control Panel Settings and Adjustments

The amplifier’s settings and controls are located on the bottom panel beneath a

gasketed, protective cover. Remove the four Phillips head screws from the center

panel to access the controls and make adjustments. Replace cover when finished

and mount the amplifier.

Specications MX500/4

Rated RMS Power @ 14.4V,

<1% THD+N

70W x 4 @ 4 Ω 90W x 4 @ 3 Ω

125W x 4 @ 2 Ω 250W x 2 @ 4 Ω Bridged

Rated RMS Power @ 12.5V,

<1% THD+N

55W x 4 @ 4 Ω 70W x 4 @ 3 Ω

90W x 4 @ 2 Ω 180W x 2 @ 4 Ω Bridged

Frequency Response 20 Hz - 20 kHz (+0, -1dB), 6.3 Hz - 30 kHz (+0, -3dB)

S/N Ratio, A-weighted,

20 kHz noise bandwidth

88 dB (Referred to rated power), 68 dB (Referred to 1 W)

Damping Factor >92 / 50 Hz @ 4 Ω, >43 / 50 Hz @ 2 Ω

Input Voltage Range 250 mV - 4 V (Low) or 750 mV - 15 V (High)

Filter Modes Low-Pass or High-Pass, defeatable

Filter Freq. Range, Slope 35 - 300 Hz, 12 dB/Octave

Detented Filter Frequency

Potentiometers

35, 80, 135, 300 Hz (Calibrated)

Input Mode Switch 2 / 3 / 4 Channel

Min Power/GND Wire 4 AWG

Fuse Rating 50A

Dimensions 9.33 in x 4.50 in x 1.77 in / 237 mm x 114.5 mm x 45 mm

Status LED’s / Protection Circuitry

There are two status indicator lights on the wiring end panel of the amplifier.

1. “POWER” (Green): Lights to indicate that the amplifier is turned on and

operating normally.

2. “PROTECT” (Red): Lights to indicate the amplifier’s protection circuitry

has been activated to prevent product failure due to thermal overload,

over current or short-circuit to the amplifier’s outputs. When this pro-

tection mode is activated, the amplifier will shut down to protect its

circuitry. When the problem is corrected, the amplifier will return to

normal operation and the “Protect” LED will shut off. Connecting the

speaker outputs to impedances lower than 2 ohms stereo (4 ohms

bridged) will also cause this protection mode to activate.

POWER

(Green LED)

PROTECT

(Red LED)

Status Note

ON OFF Normal Operation



OFF ON Thermal Protection Lasts until temp cools to normal

OFF/ON ON/OFF Over Current Green/Red LEDs alternate for 1 second

OFF ON Short Circuit Possible audible “popping” noise

Remote Turn-On

High <or> Low-Level Inputs Speaker

Outputs

(selectable via Input Voltage Switch

for each channel pair)

[FR–]

[FR+]

[RL–]

[RL+]

[RR–]

[RR+]

[FL–]

[FL+]

[REAR IN]

Source

[REM]

Battery

Fuse

(not included)

[+12V]

[GND]

[FRONT IN]

Label Wire Color Description

+12V Red Positive (+12V) Power Connection

GND Black Negative (GND) Ground Connection

REM Blue Positive (+12V) Remote Turn-On Input

FL+ White

Ch. 1

output

(+) Positive Front Left Speaker Front Bridged (+)

FL– White/Black (–) Negative Front Left Speaker

FR+ Gray

Ch. 2

output

(+) Positive Front Right Speaker

FR– Gray/Black (–) Negative Front Right Speaker Front Bridged (–)

RL+ Green

Ch. 3

output

(+) Positive Rear Left Speaker Rear Bridged (+)

RL– Green/Black (–) Negative Rear Left Speaker

RR+ Purple

Ch. 4

output

(+) Positive Rear Right Speaker

RR– Purple/Black (–) Negative Rear Right Speaker Rear Bridged (–)

Label Plug Description

FRONT

White RCA Ch. 1 / Front Left Channel Signal Input

Red RCA Ch. 2 / Front Right Channel Signal Input

REAR

White RCA Ch. 3 / Rear Left Channel Signal Input

Red RCA Ch. 4 / Rear Right Channel Signal Input

Connections

IPX7

WATER

RESISTANT

Need help?

Do you have a question about the JL Audio MX500/4 and is the answer not in the manual?

The JL Audio MX500/4 is a 4-channel Class D amplifier designed for marine applications, offering a compact and efficient solution for powering audio systems in boats. Its Class D design contributes to its small footprint and high efficiency, making it suitable for installations where space and power consumption are critical.

Function Description:

The MX500/4 serves as a power amplifier, taking a low-level audio signal from a source unit (like a head unit) and amplifying it to drive loudspeakers. It features four independent channels, allowing for flexible system configurations, such as powering four full-range speakers, two full-range speakers and a subwoofer (in bridged mode), or two subwoofers (in bridged mode). The amplifier incorporates JL Audio's NexD™ switching technology, which is a Class D design that delivers full-range bandwidth with very low distortion and high efficiency. This technology allows the amplifier to operate coolly and draw less current, which is particularly beneficial in marine environments where battery power is often limited.

The amplifier includes a variety of input and output options to accommodate different system setups. It offers both RCA (low-level) and speaker-level (high-level) inputs, making it compatible with a wide range of source units, including factory radios that may not have RCA outputs. The speaker outputs are designed to connect directly to your loudspeakers.

Important Technical Specifications:

Rated RMS Power @ 14.4V:
- 70W RMS x 4 @ 4 Ω
- 125W RMS x 4 @ 2 Ω
- 250W RMS x 2 @ 4 Ω (bridged)
Rated RMS Power @ 12.5V:
- 60W RMS x 4 @ 4 Ω
- 100W RMS x 4 @ 2 Ω
- 200W RMS x 2 @ 4 Ω (bridged)
Frequency Response: 20 Hz - 20 kHz (+0, -1dB)
S/N Ratio (A-Weighted): >104 dB (referred to rated power)
Damping Factor: >75 @ 4 Ω / 50 Hz, >50 @ 2 Ω / 50 Hz
Input Voltage Range: 250 mV - 4 V (low-level) or 750 mV - 15 V (high-level)
Filter Type: Selectable Low-Pass or High-Pass
Filter Frequency Range: 50 - 500 Hz
Filter Slope: 12 dB/octave
Dimensions: 8.50 in x 4.33 in x 1.77 in (217 mm x 110 mm x 45 mm)
Fuse Rating: 50A (external fuse)
Minimum Recommended Power Wire: 8 AWG

Usage Features:

Input Flexibility: The MX500/4 offers both low-level (RCA) and high-level (speaker wire) inputs. This allows it to be integrated with virtually any source unit, including factory radios that may not have dedicated RCA outputs. The input sensitivity is adjustable to match the output of the source unit, ensuring optimal signal transfer and minimizing noise.
Crossover Controls: Each pair of channels (Channels 1 & 2 and Channels 3 & 4) features an independent selectable filter. Users can choose between a full-range signal (no filter), a high-pass filter (HP), or a low-pass filter (LP). The filter frequency is continuously variable from 50 Hz to 500 Hz with a 12 dB/octave slope. This allows for precise tuning of the audio system, enabling users to direct specific frequency ranges to appropriate speakers (e.g., high-pass for full-range speakers, low-pass for subwoofers).
Bridged Mode Capability: Channels 1 & 2 and Channels 3 & 4 can be independently bridged to create two higher-power channels. This is useful for driving subwoofers or higher-power full-range speakers. In bridged mode, the amplifier delivers 250W RMS x 2 into a 4-ohm load.
Automatic Turn-On Options: The amplifier offers multiple turn-on options for convenience. It can be triggered by a traditional remote turn-on wire (REM), DC offset sensing (DC), or signal sensing (SIG). DC offset sensing is particularly useful for factory radios that do not provide a remote turn-on output, as it detects a small DC voltage on the speaker outputs. Signal sensing detects the presence of an audio signal.
Status/Protection LED: A multi-color LED indicator provides visual feedback on the amplifier's operational status and protection modes. Green indicates normal operation, while red indicates a protection event (e.g., thermal overload, short circuit, low impedance). This helps in quick troubleshooting.
Mounting: The compact dimensions and robust construction make it suitable for marine installations. The amplifier is designed to be mounted securely in a location that provides adequate ventilation.
Corrosion Resistance: As a marine amplifier, it is built with materials and finishes designed to resist corrosion in harsh marine environments. This includes stainless steel mounting screws and a powder-coated chassis.

Maintenance Features:

Troubleshooting Guide: The manual includes a comprehensive troubleshooting guide to help users diagnose and resolve common issues such as no power, no output, distorted output, or amplifier going into protection mode. This guide covers various scenarios and provides step-by-step solutions.
Warranty Information: JL Audio provides a limited warranty for its products, covering defects in materials and workmanship. The warranty period is typically two years from the original date of purchase, or three years if installed by an authorized JL Audio dealer. This ensures support and service for potential manufacturing defects.
Cleaning: The manual advises against using harsh chemicals or abrasive cleaners on the amplifier. A soft, damp cloth is recommended for cleaning the exterior.
Fuse Replacement: The amplifier requires an external 50A fuse. The manual provides instructions on how to properly size and install the power wire and fuse, emphasizing the importance of using the correct fuse rating for protection.
Ventilation: Proper ventilation is crucial for the amplifier's long-term reliability. The manual stresses the importance of mounting the amplifier in a location that allows for adequate airflow to prevent overheating.
Input Level Setting Procedure: The manual provides a detailed procedure for setting the input sensitivity (input level) using a digital AC voltmeter. This ensures that the amplifier receives an optimal signal from the source unit without clipping, maximizing sound quality and preventing damage to speakers.
Safety Precautions: The manual outlines important safety precautions, including warnings about working with electrical systems, potential hearing damage from loud audio, and the importance of professional installation. It also advises against operating the amplifier in an environment where it could be submerged or exposed to excessive moisture.

In summary, the JL Audio MX500/4 is a versatile and robust 4-channel marine amplifier, offering high-quality audio amplification in a compact and efficient package. Its flexible input options, comprehensive crossover controls, and durable design make it an excellent choice for enhancing audio systems in boats and other marine vehicles.