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How to Install a Line Output Converter

A Line Output Converter, or LOC, is necessary to pair an aftermarket amplifier with a factory car radio.

Here’s how you can install it in your vehicle:

  • Tap the speaker wires and connect them to the converter’s input wires.
  •  Connect the converter’s output wires to the preamp RCA inputs of the aftermarket amplifier.
  •  Connect the amplifier to your speakers/sub.

This article will discuss the installation process and wiring diagrams for different types of line output converters in great detail.

When Should You Install a Line Output Converter?

Upgrading to an aftermarket amplifier is one of the easiest ways to improve your car audio. It enhances bass and improves the overall sound by removing distortion and muddiness.

But the main issue car audio installers face in this regard is compatibility. Most aftermarket amplifiers come with RCA pre-outs that are incompatible with factory radios.

And you’ll have to upgrade to a 3rd-party radio with RCA inputs to solve this issue.

But it’s easier said than done because many modern vehicles have their radios integrated with other in-car systems. These systems include the climate control system, the navigation system, steering wheel controls, etc. Replacing the factory radio means you’ll not be able to use these features again.

This is where Line Output Converts (or LOCs) come into the equation. These converters take the speaker-level signal from the head unit and convert it into the RCA-level signal, which can be sent to the aftermarket amplifier.

How to Install a 2-Channel LOC?

LOCs come in mainly two types: 2-channel and 4-channel.

We’ll first talk about the 2-channel LOCs, which come with only two audio channels: left-front and right-front.

  • Disconnect the negative battery terminal. Since we’re installing a new component in our vehicle, we’ll have to disconnect the negative battery terminal as a safety measure against short circuits, voltage spikes, electrical shocks, etc.
  •  Locate the speaker wires of the factory head unit. You’ll have to remove the head unit from the dashboard to access the wiring.
  •  Identify the speaker wires. Once you have access to the head unit’s wiring, you’ll have to identify the speaker wires. You should check your vehicle’s radio wiring diagram for this. Or test each wire with a multimeter if you can’t find the diagram.
  •  Once you’ve identified the speaker wires, tap into them and connect them to the LOC’s input wires. While connecting, you’ll have to be careful with the polarity – connect positive speaker wires with the positive LOC input wires and vice versa.
  •  You can then use butt connectors and wire crimpers to secure these connections.
  •  Connect LOC’s outputs to the amp’s RCA inputs through two RCA cables. You’ll have to match polarity here too.
  •  Reconnect the negative battery terminal.

2-channel LOC Installation Diagram

Below is the wiring diagram of Scosche LOC2SL – a very popular 2-channel LOC.


How To Install a 4-channel LOC

Unlike their 2-channel siblings, the 4-channel LOCs have four audio channels: front-left, front-right, rear-left, and rear-right.

Regarding the installation process, the only difference is that we connect LOC inputs to the eight wires instead of the four (two for each speaker).

Similarly, you’ll need four RCA cables (instead of two) to connect LOC’s outputs to the amp’s inputs.

4-channel LOC Installation Diagram

Below is the wiring diagram of PAC LP5-4 L.O.C. PRO – a 4-channel LOC.



Installing a line output converter is necessary to upgrade to an aftermarket amplifier while keeping the same factory radio.

The common LOCs in the market are 2-channel, 4-channel, and 6-channel. Each of these LOCs has pros and cons; you should choose one according to your car’s audio system and budget.

Frequently Asked Questions

Does A Line Output Converter Need Power?

Yes, if you have an advanced-level active LOC, it’ll need a 12V power signal.

How Do You Tune A Line Output Converter?

You can tune a line output converter by adjusting its gain and crossover settings. Some high-end LCOs also have additional EQ settings that you can tweak for further customization.

How To Hook Up A Line Output Converter For A Subwoofer?

The process for pairing an LOC for a subwoofer is the same as how we pair it with our speakers. You’ll need to tap its wires, connect them with the LOC’s speaker inputs and then connect the LOC’s RCA outputs with the amplifier’s RCA inputs.

How Many Watts Can A Line Output Converter Handle?

It depends on whether a line output converter is a 2-channel or 4-channel. Or whether it’s a passive or an active converter. A regular 2-channel LOC can usually handle up to 100 watts. On the other hand, an active 4-channel LOC should handle up to 400 watts.

Do I Need An LOC If My Amp Has High-Level Inputs?

The primary reason for installing an LOC is to make the head unit’s speaker-level signal compatible with the aftermarket amplifiers’ RCA-level inputs. Therefore, if your particular amp has built-in speaker-level inputs, installing a LOC is unnecessary.

Is it better to use RCA or high-level input?

Both have their own advantages and disadvantages. The RCA-level inputs provide a cleaner sound that is less prone to interference. On the other hand, RCA -level inputs don’t require you to get an LOC, resulting in less installation time and fewer wires to deal with.

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