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How to Install a Line Output Converter

If you’ve ever installed an aftermarket amplifier in a vehicle, you’ll know that they require RCA connectors to connect with the radio.

But the OEM radios don’t have RCA pre-outs. Instead, they feature speaker-level outputs that you’ll have to convert to RCAs.

This is where you’ll need a line output converter.

Also known as LOCs, these converters are placed between your factory radio and the aftermarket amp. They connect to the factory radio through their inputs and the amp through their outputs.

In this post, we’ll learn how to install a LOC in your car/truck.

Line Output Converter Diagram

Before discussing the procedure, we’ll check out the wiring diagrams for some of the popular LOCs.

Scosche LOC2SL Wiring Diagram

Scosche takes a slightly different wiring approach in LOC2SL.

They recommend connecting the rear speakers’ wires to the input wires of the LOC. This way, the LOC will ‘sense’ the input signal from rear-speaker wires.

After this, connect LOC’s blue/white wire to the amp’s REM input and LOC’s RCA outputs to the amp’s RCA inputs via an RCA cable pair.

PAC LP5-4 L.O.C. PRO wiring diagram

The PAC LP5-4 LOC PRO takes the rather conventional approach.

You’ll need to connect the factory radio’s speaker-level outputs to the LOC’s inputs. But since it has RCA connectors as the input, you’ll need to cut them and then connect the remaining wires to the stereo’s speak-level wires – as shown in the picture below.

AudioControl LC6i Wiring Diagram

AudioControl LC7i Wiring Diagram (Factory Amplifier)

AudioControl LC7i Wiring Diagram (no Factory Amplifier)

AudioControl LC7i Wiring Diagram (no Factory Amp)

If you have a factory amplifier in your vehicle, you’ll connect the speaker-level signal from that amp (instead of the radio) to the LOC. And connect the LOC to the 3rd-party amp(s) via RCAs – as shown in the picture below.

How to Install a 2-Channel Line Output Converter

Installing any new component in your vehicle is risky. Therefore, the first thing you need to do is disconnect the negative battery terminal.

Then, remove the head unit from the dash panel to access its wiring.

Once you get access to the wiring, you’ll see that it’s a bunch of different wires. Among those wires, you’ll need to find out the speaker wires.

The color coding in 3rd-party radios’ wirings has been standardized. But that’s not the case with OEM radios, unfortunately. Therefore, you’ll have to read the owner’s manual or search for its wiring diagram on google to understand which wires correspond to the speakers.

Lucky for you, I have recently published separate blogposts about wiring diagrams and color codes in OEM radios. You can check them out below:

Once you’ve identified those wires, you’ll need to connect each speaker wire to its corresponding LOC wire. After you’ve paired them, you can use butt connectors or soldering to secure those connections.

Then, you’ll have to connect the amp to the LOC through RCA cables. Lastly, connect the negative battery terminal again and hopefully, the LOC will work fine. For more info, you can watch this video below.

How to Install a 4-Channel Line Output Converter

Installing a 4-channel LOC is similar to installing a 2-channel LOC. The only difference would be the increased number of speaker wires. A 2-channel will require four connections: Left positive, Left negative, Right positive, and Right negative.

Similarly, you’ll need to manage eight connections in a 4-channel LOC:

  • Front-Left Positive
  • Front-Left Negative
  • Front-Right Positive
  • Front-Right Negative
  • Rear-Left Positive
  • Rear-Left Negative
  • Rear-Right Positive
  • Rear-Right Negative

Frequently Asked Questions

What does a Line Output Converter do?

A Line Output Converter (or LOC) converts speaker-level signals into preamp RCA-level signals.

What Line Output Converter do I Need?

It depends on your car audio setup. If you want to use a 3rd-party amp with only two of your speakers (or a single sub), then a 2-channel LOC would be fine. But if you have four speakers + a sub, and you want to use a 6-channel amp for them, you’ll need a 6-channel LOC.

Where Does a Line Output Converter Connect?

The factory radio/amp’s speaker wires connect to the inputs of a LOC. And the aftermarket amp’s RCA wires connect to its outputs.

Does a Line Output Converter Need Power?

Only the active LOCs need +12V power to operate.

Do Aftermarket Radios Need Line Out Converters?

No. The aftermarket radios come with RCA-level outputs by default. Therefore, they don’t require any LOC.

Michael Brown is the founder of, a website that provides car audio installation guides and tips. A self-taught car audio enthusiast, Michael has been installing and modifying car stereo systems for over 15 years.

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