Line Output Converters - Do I need One and which one should I buy?

By Brian Doll, AutoHarnessHouse.com Technical support

Line Output Converters are used when adding an amp to your OEM vehicle. The speaker signals from the vehicle are a high amplitude signal that is not suitible for many aftermarket amplfiiers. Connecting speaker signals directly to the input of the amplifier can damage the equipment or cause distortion in the audio signal. This article will discuss when you do and do not need a Line Output Converter (LOC) and provide information on which units we recommend.

This article is mostly relevant to installations where the original OEM audio system is retained. If you are installing an aftermarket double din stereo system, such as a Pioneer, Sony, Alpine, or ATOTO system, the connection for the aftermarket amplifier is much more straight forward (and you should not need an LOC for connecting an amplifier to the aftermarket headunit)! Please email us with questions at inquiry@autoharnesshouse.com or head over to our Wiring and Compatibility Database Page to find plug and play parts for installing an aftermarket audio receiver. If you're looking to add Android Auto or CarPlay to your vehicle, this is probably the way to go! This page has free wiring information and pinouts for most vehicles!

Do I need a Line Output Converter?

If you are installing an aftermarket amp in your vehicle (either for the existing car speakers or for adding a subwoofer, the answer to this question will depend on the amplifier that you're installing. You will need a Line Output Converter if the new amp isn't designed to connect to speaker level signals. In some cases, the amp will have a built in Line Output Converter and you'll be able to connect the speaker-level signals directly to the new amp (No LOC needed!). If the amplifier only has RCA inputs, generally this means that line level signals are required. The purpose of the LOC is to convert the speaker-level signals to line level signals without distorting the audio signal. In summary, if you are connecting an amp to the speaker signals in your OEM audio system, you will need to convert the signal to a line level signal unless the amplifier already has circuitry to account for speaker level signals.

Recommended products:

This section provides a list of parts that we recommend based on thousands of hours of hands on experience with car audio!

The Line Output Converter

The gold standard in Line Output converters, is the AudioControl lineup. These can tend to be on the more expensive side but we've been impressed with the features and the quality that AudioControl offers.

Editor's Pick - AudioControl LC2i Pro

If you are installing an subwoofer and amp, the LC2i Pro will suit your needs. It only has 2 channels so if more than 2 speaker channels will be connected to the new amplifier, then you may need to check out the other models below. This unit has the option of adding a level control so that you can remotely adjust the level of the subwoofer and it also has very precise control of the bass frequencies. The LC2i Pro also has built in load resistors which will be handy if you are disconnecting the factory speakers. Another helpful feature is that these units will detect sound and will turn on when a signal is detected. No need to run a separate Amp Turn-on wire (the signal can be used for the remote turn-on for the amp also).

The AudioControl LC2i is a stripped down (and cheaper) version of the LC2i Pro. If you do not need the load resistors or finer AccuBass adjustment, this version may suit your needs.

Used for 4+ Audio Channels - AudioControl LC7i

Need more than 2 channels? The AudioControl LC7i will give you the space you need. This unit has the same features as the LC2i with a couple extra suprises and it allows for 3 stereo input and 3 output channels. You still have the remote level control for the subwoofer and will have individual output level controls per channel.

Budget Model - Scosche LOC2SL

We know that money can be tight and that you do not want to pay for features that you aren't going to use. For about $20, the Scosche LOC2SL will give you the option for a remote subwoofer level control and individual level controls. You will need to run a separate remote turn-on lead for this unit but it is designed (and designed in America!) to be bullet-proof. Nothing special about this unit but it will fit the bill if you are adding an aftermarket subwoofer. The Scosche SLC4 is available if you need more channels.

---

Splice Wiring Adapter - Wiring in your New Amp

Here at AutoHarnessHouse.com, we offer a number of splice adapters or jumper adapters designed to connect to the back of your OEM headunit. These adapters allow you to tie into or cut speaker signals so that signals can be routed to an aftermarket amplifier without damaging the factory wiring harness. Here are listing pages for some of these products:

Honda (2008+)

Nissan (All Available Model Years)

Subaru (All Available Model Years)

Toyota (1987-2019)

Toyota (2018+)

All of these adapters are designed to connect behind the OEM headunit. They use high quality wire and can be used to cut or "T" into speaker signals instead of tying directly into the factory wiring.

If you need connections for the output of the OEM amplifier, just let us know what you need and we will do our best to help you!

Load Resistors

We haven't discussed Load Resistors here. Please see the full discussion on the "Do I Need Load Resistors?" page. These devices can help to stabilize the audio signal if you are amplifying the existing speakers in the car but usually they aren't needed for an aftermarket subwoofer install. If you need Load resistor, we suggest the AudioControl AC-LGD 20 Load Generating Device (Load Resistor):

Final Thoughts

We wish you the best with your install! As automobiles have become more complex, so have the infotainment systems. Hopefully this article has provided you with enough information to install your equiptment right way. Our support team is here and happy to help if you have questions or are confused about details. Email us at inquiry@autoharnesshouse.com if there is anything that we can clarify or if you need something more custom than the standard, recommended set of parts for your vehicle.

---