Integrating an aftermarket subwoofer into a modern factory audio system often presents a significant challenge: the head unit is rarely designed to output a clean, full-range signal suitable for high-performance amplification. Without the Best LOC for Subwoofer in your signal chain, you risk losing critical low-end frequencies, introducing unwanted noise, or failing to trigger your amplifier correctly.
A quality line output converter bridges the gap between high-level speaker signals and the RCA inputs required by your aftermarket gear. By selecting a device that properly handles factory signal processing and voltage requirements, you can achieve a balanced, powerful sound system that retains your vehicle's original steering wheel controls and head unit functionality.
You may also want to compare Best Loaded Subwoofers, Best Loaded Subwoofer Boxes, and Best Loaded Car Subwoofers.
Best LOC for Subwoofer
Quick Comparison
| Product | Best For | Key Strength | Score |
|---|---|---|---|
| AudioControl LC2i Line Output Converter | Best Overall | AccuBASS technology restores bass roll-off for improved low-end response. | 4.9 |
| AudioControl LC1i Line Output Converter | Advanced Signal Integration | Onboard load selection ensures compatibility with modern factory amplifiers. | 4.5 |
| CT Sounds CT-LC2 Line Output Converter | Dedicated Bass Enhancement | BassLift Technology effectively restores factory-restricted low frequencies. | 4.4 |
| Scosche LOC2SL Line Output Converter | Includes Remote Level Control | Remote control knob for convenient, real-time bass level adjustment. | 4.3 |
| Kicker 46KISLOC2 Line Output Converter | Automatic Remote Turn-On | Automatic remote turn-on via DC offset simplifies amplifier wiring. | 4.6 |
How We Chose
- Signal Processing Capabilities: Ability to correct factory bass roll-off and maintain frequency response.
- Input Handling: Capacity to accept high-wattage speaker-level signals without clipping or distortion.
- Integration Features: Inclusion of remote turn-on triggers and ground isolation to eliminate noise.
- Installation Versatility: Compact design and mounting options for tight vehicle spaces.
- Control Options: Availability of remote level adjustment for real-time bass management.
1 AudioControl LC2i Line Output Converter — Restores Bass Roll-Off
Integrating an aftermarket subwoofer into a factory car audio system often results in diminished low-frequency output due to factory-installed bass roll-off. The AudioControl LC2i 2-Channel Line Output Converter addresses this by utilizing proprietary AccuBASS processing technology, which actively corrects and restores bass frequencies as volume levels increase, ensuring a consistent audio profile.
Designed for versatility, the AudioControl LC2i converts speaker-level signals up to 400W per channel into high-quality pre-amp output signals. This allows for the seamless addition of subwoofers and amplifiers while maintaining the use of original factory volume and steering wheel controls. Its compact chassis, measuring 5.4”L x 3.25”D x 1.5”H, includes integrated mounting brackets to simplify installation in space-constrained vehicle interiors.
The unit offers flexible control options, including fixed and variable outputs with discrete onboard level adjustments. For users seeking further customization, it supports the optional ACR-1 dash knob remote for real-time subwoofer level control from the driver’s seat. The Great Turn On (GTO) signal sense feature provides automatic power management, while the Remote Out terminal can trigger up to two additional devices, such as external amplifiers or crossovers, down the signal chain.
Installation requires a stable power source, with a direct 12V line from the battery or a power distribution block recommended. The manufacturer specifies the use of 18 AWG wire and a 1A fuse to ensure safe and reliable operation. While highly compatible with most factory head units, users should note that the device does not retain fader control when multiple amplifiers are utilized in the signal path.
Best for: Drivers looking to add a subwoofer to a factory stereo system while restoring bass frequencies lost to factory roll-off.
Skip if: Users requiring fader control for multiple amplifiers or those who prefer a unit with an included dash remote.
PROS
- AccuBASS technology restores bass roll-off for improved low-end response.
- Compact dimensions and integrated brackets facilitate easy installation.
- GTO signal sense enables automatic power-on functionality.
- Remote Out capability triggers additional audio components.
CONS
- Does not retain fader control when running multiple amplifiers.
- ACR-1 dash remote is sold separately.
2 AudioControl LC1i Line Output Converter — Advanced Signal Integration
Integrating aftermarket audio components into a modern vehicle often requires managing complex factory signals, and the AudioControl LC1i Line Output Converter addresses this by converting high-power speaker-level signals—up to 400W—into clean, high-quality pre-amp outputs. This allows you to add subwoofers or amplifiers while maintaining your factory head unit and steering wheel controls.
A standout feature for modern vehicle compatibility is the onboard load selection, which includes 20-ohm, 60-ohm, and 20k-ohm settings. This ensures that factory amplifiers correctly detect a speaker load, preventing the system from muting or shutting down when you tap into the audio signal. The unit also functions as a line driver, providing an optimized signal to your downstream equipment for improved audio consistency.
Installation flexibility is prioritized through several design choices. The GTO (Great Turn On) signal sense automatically powers the device when audio is detected, and the Remote Out feature can trigger your external amplifiers, simplifying the wiring process. For those dealing with unwanted noise, a selectable ground isolation switch helps eliminate common issues like alternator whine or ground buzz.
The AudioControl LC1i is built with a compact slim chassis measuring 4.8 inches by 3 inches by 1 inch, making it easy to tuck away in tight vehicle spaces. For added convenience, it supports the optional ACR-1 dash remote, which provides direct control over subwoofer levels from the driver's seat.
Best for: Drivers looking to add aftermarket subwoofers or amplifiers to a factory stereo system while retaining full OEM functionality.
Skip if: Users who do not require a line driver or signal integration for factory head units and prefer a simpler, non-powered signal converter.
PROS
- Onboard load selection ensures compatibility with modern factory amplifiers.
- Built-in line driver boosts weak signals for optimal amplifier performance.
- Selectable ground isolation effectively reduces alternator whine and ground buzz.
- Compact slim chassis allows for flexible installation in tight vehicle locations.
CONS
- ACR-1 dash remote is sold separately rather than included in the box.
3 CT Sounds CT-LC2 Line Output Converter — Dedicated Bass Enhancement
Integrating a subwoofer into a factory audio system often results in underwhelming low-end output due to the inherent bass roll-off programmed into stock head units. The CT Sounds CT-LC2 2-Channel Premium Line-Out Converter with BassLift addresses this by specifically targeting factory signal limitations, allowing users to bridge the gap between high-level speaker outputs and aftermarket amplification.
At the core of this unit is BassLift Technology, which is engineered to restore and compensate for the frequencies typically lost in factory-tuned systems. By converting high-level signals into a clean, low-level RCA input, the CT Sounds CT-LC2 provides a dedicated path for signal processing. It features distinct outputs, offering both a Full-Range Main Output for your primary speakers and a Low-Pass Bass Output specifically for your subwoofer, ensuring each component receives the appropriate frequency range.
Installation is designed to be straightforward, supported by an included 34-page product manual that provides step-by-step guidance. This documentation is essential for users navigating the complexities of tapping into factory wiring, ensuring that the conversion process maintains signal integrity without requiring a complete head unit replacement.
Choosing the right converter is a balance between signal restoration and ease of integration. While this unit excels at bringing life back to factory systems, it is a specialized tool for those looking to retain their original dashboard aesthetic while upgrading their audio performance. It serves as a critical bridge for any build focused on adding a subwoofer to an otherwise unmodified factory audio environment.
Best for: Users looking to add a subwoofer to a factory car audio system while compensating for built-in bass roll-off.
Skip if: Users who have already replaced their factory head unit with an aftermarket receiver that includes dedicated RCA subwoofer outputs.
PROS
- BassLift Technology effectively restores factory-restricted low frequencies.
- Provides dedicated Full-Range and Low-Pass RCA outputs for precise signal routing.
- Includes a comprehensive 34-page manual for guided installation.
- Simplifies integration by converting high-level signals to low-level RCA inputs.
CONS
- Requires manual splicing into factory speaker wiring.
- Limited to 2-channel conversion, which may not suit complex multi-zone factory systems.
4 Scosche LOC2SL Line Output Converter — Includes Remote Level Control
Integrating an aftermarket subwoofer into a factory car audio system requires a reliable signal conversion, and the Scosche LOC2SL Line Output Converter provides a direct solution by transforming speaker-level signals into RCA line-level outputs. This device is specifically engineered to bridge the gap between stock head units and external amplifiers, ensuring that your audio signal remains clean and compatible with high-performance subwoofer setups.
The Scosche LOC2SL Line Output Converter features a compact and durable design, allowing for flexible installation in tight vehicle spaces. By converting speaker-level signals, it enables the use of an aftermarket amplifier without the need for complex rewiring of the factory stereo system. This approach helps maintain the integrity of the original dashboard setup while enabling significant upgrades to the vehicle's low-frequency output.
Beyond its primary conversion function, the unit includes a remote control knob, which grants users the ability to adjust subwoofer levels directly from the driver's seat. This level of control is essential for fine-tuning bass response on the fly, ensuring that the audio experience can be tailored to different music genres or personal preferences without accessing the amplifier directly.
Designed for versatility, this converter is built to minimize signal interference, which is critical for achieving high-fidelity sound in a custom car audio environment. With its focus on seamless integration and optimal signal quality, the Scosche LOC2SL serves as a functional interface for enthusiasts looking to enhance their car's audio performance through a dedicated subwoofer.
Best for: Drivers looking to add an aftermarket subwoofer and remote bass control to a factory car stereo system without replacing the head unit.
Skip if: Users who already have an aftermarket head unit with dedicated RCA subwoofer pre-outs, as this converter would be redundant.
PROS
- Remote control knob for convenient, real-time bass level adjustment.
- Compact design facilitates easier installation in constrained vehicle interiors.
- Seamless integration with factory stereos to preserve original dashboard aesthetics.
- Minimized signal interference for cleaner audio output to the amplifier.
CONS
- Requires manual wiring into the existing speaker lines, which may be more complex than plug-and-play solutions.
5 Kicker 46KISLOC2 Line Output Converter — Automatic Remote Turn-On
Integrating an aftermarket amplifier into a factory audio system often requires a reliable signal interface to maintain audio integrity. The Kicker 46KISLOC2 K-Series Stereo Line-Output Converter serves this purpose by converting high-level speaker signals into low-level RCA outputs, allowing for seamless integration with external subwoofers or amplifiers.
Designed for versatility, the Kicker 46KISLOC2 accepts an input signal of up to 55 watts (16 volts), making it compatible with a wide range of factory head units. Its primary technical advantage is the automatic remote turn-on feature, which utilizes DC offset to generate a 12-volt, 100 milli-amp remote signal. This eliminates the need to manually wire a switched ignition source to trigger your amplifier.
The unit focuses on maintaining signal fidelity, ensuring that the audio output retains its original characteristics across various volume levels. By utilizing existing factory speaker wiring, the installation process is streamlined, providing a direct path to upgrade your vehicle's low-frequency performance without replacing the head unit.
Measuring 6 inches in length and 5 inches in width, the device is compact enough to be tucked behind dashboards or within tight installation spaces. It comes backed by a 1-Year Manufacturer Warranty, providing coverage for the hardware during the initial period of use.
Best for: Vehicle owners looking to add an aftermarket amplifier to a factory radio while utilizing an automatic remote turn-on trigger.
Skip if: Users who require high-end signal processing features like built-in equalization or those whose factory systems utilize complex digital data buses that require specialized integration modules.
PROS
- Automatic remote turn-on via DC offset simplifies amplifier wiring.
- High input handling of up to 55 watts per channel.
- Maintains sonic accuracy across various volume levels.
CONS
- Limited to basic signal conversion without advanced audio tuning or equalization controls.
Best LOC for Subwoofer Buying Guide
Understanding Signal Conversion
A line output converter (LOC) is essential when you want to add an amplifier to a factory radio that lacks RCA outputs. It takes the high-voltage signal meant for your door speakers and steps it down to a low-voltage signal that an aftermarket amplifier can process. Choosing the right unit ensures that the signal remains clean and free of the distortion often associated with cheaper, passive converters.
When selecting a unit, consider the maximum input voltage it can handle. Some factory systems output high power levels that can overwhelm basic converters. Ensure your chosen LOC is rated for the wattage output of your factory amplifier or head unit to prevent signal clipping and potential hardware damage.
The Importance of Bass Restoration
Many factory head units are programmed to reduce bass output as the volume increases to protect the stock speakers from blowing. This 'bass roll-off' can leave your new subwoofer sounding thin at higher volumes. Advanced LOCs feature proprietary processing, such as AccuBASS or BassLift, to detect this roll-off and actively restore the low-frequency content.
If you are building a system specifically for deep, punchy bass, a converter with active bass restoration is a critical investment. It allows you to reclaim the lost signal, ensuring that your subwoofer performs as intended regardless of the volume level set on your factory head unit.
Remote Turn-On and System Integration
Modern vehicles often lack a dedicated remote turn-on wire, making it difficult to power on your aftermarket amplifier. Many high-quality LOCs solve this by sensing the audio signal or DC offset from your speaker wires and generating a 12V remote turn-on signal automatically. This feature simplifies installation significantly by removing the need to tap into complex vehicle wiring.
Look for units that offer selectable turn-on modes. This flexibility allows you to choose between signal sensing or manual control, ensuring compatibility with a wider range of vehicle electrical systems and preventing issues like amplifier 'pop' during startup.
Managing Noise and Ground Loops
Alternator whine and ground buzz are common frustrations in car audio installations. These noises are often caused by ground loops between the factory head unit and the aftermarket amplifier. A converter with a selectable ground isolation switch can be a lifesaver, allowing you to break the ground loop and eliminate unwanted noise from your signal path.
Always prioritize proper grounding during installation. Even with a high-quality LOC, poor grounding practices can introduce noise. Use the recommended wire gauge and ensure your power and ground connections are secure to maintain the integrity of your audio signal.
Installation and Mounting Considerations
Space is often at a premium in modern vehicle dashboards and trunk areas. A compact, slim-chassis LOC is easier to hide behind the dash or mount securely in a trunk cavity. Integrated mounting brackets are a significant advantage, as they allow for a professional, secure installation that prevents the unit from rattling or coming loose over time.
Before purchasing, measure the available space in your intended mounting location. Consider the length of the unit including the wiring connectors, as these often add significant depth. Choosing a unit that fits your specific vehicle layout will save time and frustration during the installation process.
Frequently Asked Questions
Do I need an active or passive LOC for my subwoofer?
For subwoofer applications, an active LOC is highly recommended. Active units require a 12V power source but offer superior signal quality, bass restoration, and remote turn-on capabilities that passive units lack.
Will an LOC affect my factory steering wheel controls?
No, a properly installed line output converter does not interfere with factory steering wheel controls or volume adjustments. It simply taps into the speaker signal wires to create an output for your amplifier.
Can I use an LOC to power my door speakers as well?
Yes, many 2-channel or multi-channel LOCs can be used to provide signal to amplifiers for both subwoofers and full-range door speakers, provided the unit has enough channels to support your setup.
What should I do if I hear a buzzing sound after installation?
If you hear buzzing, first check your ground connection. If the ground is secure, use the ground isolation switch on your LOC (if equipped) to see if it eliminates the noise. Ensure your RCA cables are routed away from power wires.
Does the LOC need to be fused?
Yes, when using an active LOC that requires 12V power, it is standard practice to use a 1A fuse on the power line to protect the unit and your vehicle's electrical system.
Conclusion: Our Top Pick
For those seeking the most reliable and feature-rich integration, the AudioControl LC2i Line Output Converter stands out as the premier choice. Its dedicated AccuBASS technology effectively combats factory bass roll-off, ensuring your subwoofer delivers a full, rich sound that remains consistent even at higher volumes. The compact design and ability to trigger downstream devices make it a versatile solution for almost any aftermarket audio upgrade.
While other options provide basic signal conversion, the LC2i offers the specific processing power needed to truly enhance the low-end performance of a factory system. By choosing this unit, you gain precise control over your bass levels and a robust, clean signal path that respects the integrity of your vehicle's original audio architecture.