Metra 2 Channel Line Output Converter (LOC) Wiring Diagram & Installation
This guide details the installation of a Metra LOC, converting speaker audio to RCA outputs, enabling aftermarket amplifier addition to factory systems.
Metra Line Output Converters (LOCs) are essential components for integrating aftermarket audio systems with factory car stereos. They bridge the gap between the high-level speaker outputs of a factory radio and the low-level RCA inputs required by most amplifiers. Metra offers a diverse range of LOCs, designed to handle various power levels and integration scenarios.
The AX-MLOC720, a popular 2-channel LOC, exemplifies Metra’s commitment to quality and functionality. These converters allow users to retain their vehicle’s original stereo while enjoying the benefits of a more powerful and customized audio experience. Understanding the purpose and capabilities of Metra LOCs is the first step towards a successful car audio upgrade. They are designed for ease of installation and reliable performance.
What is a Line Output Converter?
A Line Output Converter (LOC) transforms high-level speaker signals into low-level RCA signals. Factory car stereos typically output audio at speaker level, which is a higher voltage and power signal. Aftermarket amplifiers, however, require a low-level signal for optimal performance and to prevent distortion. The LOC acts as an intermediary, reducing the voltage and impedance to a compatible level.
Essentially, it “steps down” the signal. This conversion allows you to add an aftermarket amplifier and subwoofer to a vehicle without replacing the original factory radio. LOCs are crucial for maintaining factory features while enhancing the audio system’s capabilities, providing a cleaner and more powerful sound.
Applications of a 2-Channel LOC
A 2-channel LOC, like the Metra AX-MLOC720, is ideal for adding a single aftermarket amplifier to your vehicle’s audio system. This setup commonly powers a dedicated subwoofer, enhancing the bass response without altering the factory front or rear speakers. It’s also suitable for powering a pair of door speakers, upgrading the overall sound quality.
Furthermore, a 2-channel LOC can be used with OEM radios to add aftermarket amplification. The LOC detects audio signals and generates a 12V output to activate the amplifier. This is particularly useful in vehicles lacking a dedicated remote turn-on wire, simplifying the installation process and expanding audio possibilities.
Understanding the Metra AX-MLOC720
The AX-MLOC720 is a 2-channel adjustable Line Output Converter with a built-in amplifier remote generator, designed for OEM and aftermarket audio upgrades.
Key Features and Specifications
The Metra AX-MLOC720 boasts several key features enhancing audio system integration. It handles up to 80 watts per channel continuously, preventing overheating during operation. The input circuitry actively corrects crossover distortion, a common issue with standard LOCs, providing a superior 6:1 high-to-low level conversion.
Output audio levels are infinitely adjustable via onboard potentiometers, allowing precise signal tuning. The remote output, or amplifier trigger, is rated at 500mA (12V), capable of driving external relays for increased current demands.
This LOC triggers instantly upon detecting a DC voltage above 5V on the left audio input or a low audio signal, and shuts off after 60 seconds of signal absence. It’s designed for stereo speaker outputs or OEM amplifier wires up to 80 watts per channel.
Power Handling Capabilities (80 Watts/Channel)
The Metra AX-MLOC720 is engineered to reliably handle substantial power, specifically rated at 80 watts per channel for continuous input. This robust capacity ensures stable operation even with higher-output factory stereos or amplifiers, preventing overheating and signal degradation.
This specification makes the LOC suitable for a wide range of vehicles and audio systems. It allows for clean conversion of speaker-level signals without compromising audio quality.
The design prioritizes thermal management, ensuring long-term performance and reliability. Exceeding this wattage rating may lead to diminished performance or potential damage, so adherence to the 80-watt limit is crucial for optimal functionality and longevity of the converter.
Automatic Amplifier Turn-On Functionality
The Metra AX-MLOC720 incorporates an intelligent automatic amplifier turn-on feature, eliminating the need for a separate remote wire connection in many installations. This functionality detects the presence of an audio signal or DC voltage on the left audio input wire (white wire) exceeding 5V.
Upon signal detection, the LOC instantly generates a 12V output, rated at 500mA, capable of directly triggering most aftermarket amplifiers.
If no audio signal is present, the 12V output will automatically shut off after 60 seconds, conserving power and preventing unnecessary amplifier operation. This feature simplifies installation and provides a seamless integration with existing vehicle systems, even supporting outboard relays for higher current demands.
Wiring Diagram Overview
The LOC connects to speaker wires for input, converting them to RCA outputs for amplifiers, and features a 12V remote turn-on output.
Input Connections: Speaker Level Audio
Connecting the LOC to your vehicle’s speaker outputs is the initial step. Identify the left and right speaker wires – typically, these are found behind the factory radio or amplifier. The Metra AX-MLOC720 accepts speaker level inputs, meaning you connect directly to the existing speaker wires without modifying the factory wiring extensively.
The white wire represents the left channel input, while the white/black wire is the right channel input. Ensure a secure connection using appropriate connectors; solder and heat shrink tubing are recommended for a reliable, long-lasting connection. Proper polarity is crucial; incorrect wiring can result in phase cancellation and poor audio performance. The LOC is designed to handle up to 80 watts per channel continuously.
Output Connections: Line Level Audio
The Metra LOC converts speaker-level signals into line-level RCA outputs, ready for connection to your aftermarket amplifier. Typically, you’ll find red and white RCA jacks on the LOC – red for the right channel and white for the left. Use high-quality RCA cables to minimize signal loss and interference.
Connect these RCA cables directly to the corresponding inputs on your amplifier. The LOC features onboard potentiometers allowing for precise adjustment of the output signal level. This is crucial for matching the LOC’s output to your amplifier’s input sensitivity, ensuring optimal performance and preventing distortion. A 6:1 step-down ratio is provided.
Remote Turn-On Output (500mA)
The Metra LOC incorporates a built-in amplifier remote generator, simplifying installation by eliminating the need for a separate remote wire run. This feature detects audio signals, triggering a 12V output rated at 500mA. This output can directly activate most aftermarket amplifiers.
If your amplifier requires more current, the 500mA output can easily control an external relay. The LOC’s remote output activates instantaneously upon detecting a DC voltage above 5V on the white (left) audio input or a low audio signal. It will deactivate 60 seconds after signal loss, conserving battery power.
Wiring Instructions ⎯ Step-by-Step
Begin by carefully identifying the speaker output wires from your stereo or OEM amplifier, then connect the input wires for left and right channels.
Identifying Speaker Output Wires
Locating the correct speaker wires is crucial for successful installation. Typically, these wires are found behind the factory radio or amplifier. Consult your vehicle’s wiring diagram, if available, to accurately identify the left and right speaker outputs. Common color coding exists, but varies by manufacturer; however, often positive wires are marked with a stripe.
The Metra AX-MLOC720 requires connection to these speaker level outputs. Use a multimeter to confirm polarity; the positive terminal will show a positive voltage when the radio is on and playing audio. Carefully strip a small portion of insulation from each wire to expose the conductor for connection. Ensure no stray strands short circuit against each other or the vehicle’s chassis during the process. Proper identification prevents incorrect wiring and potential damage.
Connecting Input Wires (Left & Right Channels)
Connect the identified speaker wires to the Metra LOC’s input terminals, observing correct polarity. The LOC designates specific terminals for left and right channels; typically, these are labeled or color-coded. Match the positive wire from the vehicle’s speaker system to the positive terminal on the LOC, and the negative to negative.
Secure connections are vital for optimal signal transfer. Use crimp connectors or solder to ensure a firm, reliable connection. Avoid loose connections, which can introduce noise or signal loss. The white wire on the LOC is the left audio input, triggering the remote turn-on with 5V DC or a low audio signal.
Connecting Output Wires (RCA)
Connect the RCA output cables from the Metra LOC to the corresponding input jacks on your aftermarket amplifier. Typically, red RCA cables represent the right channel, while white or black represent the left. Ensure a snug fit for each connection to prevent signal interference or loss.
Use high-quality RCA cables to minimize noise and maximize signal clarity. Shielded cables are recommended, especially in environments with potential electrical interference. Double-check all connections before powering on the system to avoid potential damage to the amplifier or LOC.
Grounding and Power Connections
Securely ground the LOC to a clean metal chassis point and connect the 12V power wire to a switched power source for operation.
Proper Grounding Techniques
Achieving a solid ground connection is crucial for optimal performance and minimizing noise. Locate a clean, unpainted metal surface on the vehicle’s chassis, ensuring it’s free from rust or corrosion. Scrape away any paint if necessary to expose bare metal.
Use a short, thick gauge ground wire (16-18 AWG is generally sufficient) and securely attach it to the chassis using a screw and star washer. The star washer ensures good contact. Avoid grounding to components that move or are already carrying a significant electrical load.
A poor ground can introduce unwanted hum or distortion into the audio signal, so double-check the connection for tightness and conductivity. Proper grounding is fundamental for a clean and reliable audio system.
12V Power Source Connection
Connect the LOC’s 12V power wire to a switched 12V source, meaning it only provides power when the vehicle’s ignition is on; Avoid using a constant 12V source, as this could drain the battery. A suitable source is often the vehicle’s radio power wire or an accessory power wire.
Use a properly sized fuse (typically 1-2 amps) inline with the 12V power wire, as close to the power source as possible, to protect the LOC and the vehicle’s electrical system. Ensure the fuse is the correct amperage rating.
Securely connect the wire and fuse holder, insulating any exposed connections to prevent shorts.
Adjusting the Output Level
Fine-tune the onboard potentiometers to optimize the audio signal, ensuring a clean and distortion-free output to your amplifier for best sound quality.
Using Onboard Potentiometers
The Metra AX-MLOC720 features high-quality potentiometers for infinitely adjustable output levels. These allow precise control over the signal sent to your aftermarket amplifier, crucial for achieving optimal performance. Begin with the potentiometers turned down low, then gradually increase the level while playing music.
Monitor the amplifier’s input level to avoid clipping or distortion. Listen carefully for any unwanted noise or signal degradation. The goal is to maximize the signal strength without exceeding the amplifier’s capabilities. Adjust each channel independently for a balanced soundstage. Proper adjustment ensures a clean, powerful, and accurate audio reproduction experience.
Optimizing Audio Signal
Achieving optimal audio requires careful signal matching. The LOC corrects crossover distortion, providing a 6:1 step-down from speaker to line level. Ensure the input isn’t overloading the converter – 80 watts/channel is the maximum continuous input.
Fine-tune the onboard potentiometers after initial setup. A clean, strong signal minimizes noise and maximizes amplifier efficiency. Experiment with slight adjustments to find the “sweet spot” for your specific vehicle and audio system. Proper gain staging is key to a dynamic and distortion-free listening experience, enhancing overall sound quality.
Troubleshooting Common Issues
If no sound occurs, verify all connections and power. An amplifier failing to activate suggests a remote turn-on issue or insufficient voltage.
No Output Signal
Diagnosing a lack of audio output from your Metra LOC requires a systematic approach. First, meticulously re-examine all input and output connections, ensuring they are secure and correctly matched – speaker wires to the LOC input, and RCA cables to the amplifier input. Confirm the source unit (radio or OEM amplifier) is producing sound; test the speakers directly connected to it.
Next, verify the 12V power and ground connections to the LOC are solid. A weak or absent ground is a frequent culprit. Utilize a multimeter to confirm voltage at the LOC’s power wire. Finally, check the onboard potentiometers; they might be inadvertently turned down, resulting in a muted signal. Ensure the input signal detection threshold is appropriate for your audio source.
Amplifier Not Turning On
If your amplifier isn’t powering on despite the LOC being connected, several factors could be at play. Begin by verifying the LOC’s remote turn-on output is active; use a multimeter to check for 12V at the remote wire when the head unit is on. Ensure the amplifier’s remote input is correctly connected to this wire.
Confirm the LOC is detecting an audio signal – it needs a DC voltage above 5V on the white (left) audio input or a low audio signal. Check the 500mA remote output rating; if your amplifier requires more current, an outboard relay might be necessary. Finally, inspect the amplifier’s power and ground connections for security and proper grounding.
Safety Precautions
Always disconnect the vehicle’s battery negative terminal before starting installation to prevent electrical shock and short circuits during wiring.
Disconnecting Battery Before Installation
Prior to commencing any wiring procedures with the Metra LOC, it is absolutely crucial to disconnect the negative terminal of your vehicle’s battery. This simple step safeguards against accidental short circuits, which could potentially damage the LOC, your vehicle’s electrical system, or even cause personal injury.
Locate the battery, typically under the hood, and use a wrench to loosen the nut securing the negative cable. Carefully remove the cable from the terminal, ensuring it doesn’t accidentally make contact during the installation process. Securing the cable away from the terminal is recommended; This precaution eliminates the risk of live circuits while you are working with the wiring, providing a safe environment for a successful installation.
Avoiding Short Circuits
Short circuits pose a significant risk during LOC installation, potentially damaging components and creating a fire hazard. Carefully inspect all wiring for exposed copper strands before making connections. Utilize proper wire connectors, crimp terminals, or solder joints to ensure secure and insulated connections.
Avoid routing wires near sharp metal edges or areas prone to abrasion. Employ wire loom or electrical tape to protect exposed wiring from accidental contact with the vehicle’s chassis. Double-check all connections after installation to confirm no bare wires are present. A blown fuse is a warning sign – investigate immediately before restoring power!
Resources and Documentation
Access Metra’s official website (metraonline.com) for comprehensive support and download the AX-MLOC720 installation PDF for detailed diagrams.
Metra Online Documentation (metraonline.com)
Metra’s official website, metraonline.com, serves as a central hub for all product-related information, including the AX-MLOC720. Here, you’ll find frequently asked questions, troubleshooting guides, and updated documentation to assist with your installation. The website provides a searchable database allowing users to quickly locate specific information regarding wiring, compatibility, and optimal performance settings for the line output converter.
Furthermore, Metra offers a dedicated support section where you can submit inquiries or access contact information for direct assistance. Regularly checking metraonline.com ensures you have the latest resources available, as product specifications and installation procedures may be updated periodically. This online resource is invaluable for a smooth and successful installation process.
AX-MLOC720 Installation Instructions PDF
The official AX-MLOC720 installation instructions are available as a downloadable PDF document from Metra’s static server (metra-static.s3.amazonaws.com). This comprehensive guide, dated February 8, 2025, details every step of the installation process, from identifying speaker wires to adjusting the output levels. It explicitly outlines the LOC’s function: converting speaker-level audio to line-level for aftermarket amplifiers or OEM upgrades.
The PDF includes crucial information regarding the 80-watt per channel power handling, the automatic amplifier turn-on feature, and the 500mA remote turn-on output. It emphasizes proper grounding techniques and cautions against short circuits, ensuring a safe and effective installation. Accessing this PDF is vital for a correct and optimized setup.