How to Tell If Line out Converter Is Bad?

Adding an aftermarket amplifier to your car audio system is a great way of adding more volume, detail, and depth to your music, especially when using a weak factory radio. However, most factory radios lack preamp outputs for connecting to an amp. Line-out converters help to connect an aftermarket amp to a factory radio by converting speaker-level outputs of a factory radio into RCA preamp-level for the amplifier. However, if your line-out converter is bad, you will not be able to get sound. In this article, we will show you how to tell if a line-out converter is bad.

Why Use a Line Out Converter?

It is often challenging and confusing to install an amplifier with a car factory radio. Most aftermarket amplifiers are often designed for use with unbalanced low-level inputs (RCA). Unfortunately, most factory radios are not designed to work with inputs from balanced inputs that come with aftermarket radios. With such a connection, there is a high risk of damaging the radio.

Also, most amps come with a basic resistive conversion from high-level to low-level signals. A line-out converter (LOC) takes a high-level input from a factory radio and converts it to a low-level RCA output that can be hooked to an aftermarket amp.

Symptoms of a Bad Line out Converter

Symptoms of a Bad Line out Converter

Many car music lovers add a LOC to their car music system, especially when using a factory radio. Sometimes, the LOC can develop issues that may affect the music system. Here are the possible signs that your LOC is having problems:

  • No sound is coming from the sub despite turning the amplifier on
  • No sound coming from the speakers
  • The signal is cutting out somewhere in the audio setup but other components seem good
  • RCA cable breaks down
  • Unexplainable problems with the subwoofer
  • Problems with the factory radio
  • Sound is fading as you drive
  • The subwoofer is humming loudly

How to Tell If Line out Convertor Is Bad

If you suspect that your LOC is bad and you have noticed the aforementioned symptoms, you should test it to determine if it is indeed bad. To do this, set a multimeter to AC. Then turn on the multimeter. Play any song and check the sub-input terminal voltage. If there is any voltage present, it means your sub is not working properly. It is likely the LOC is not working.

How to Fix a Bad Line out Converter

If you suspect the problem is a bad RCA, you can try to fix the issue by replacing the RCA cable connecting the LOC to the amp. If that fixes the problem, then you are good to go. If that does not fix the problem, then you need to replace the LOC to resolve the issue.

If you have confirmed that the LOC does not have any issue and the amp is turned on, and the factory radio is outputting voltage but there is no audio or the audio is cutting out intermittently, it is likely that the factory radio has issues.

The issue might be caused by the LOC not putting a load on the factory radio speaker outputs. In this case, the high-level speaker line will not have any resistance. As a result, the amp might think there are no speakers hooked to it such that it will fail to output an audio signal or the audio output signal will drop out intermittently.

If you have installed a LOC but you are experiencing issues with the audio output, your car factory radio may require extra load for normal operation. You can track the factory radio to think that speakers are present whenever it thinks there are no speakers attached. To do this, install resistors across the negative and positive wires of the factory radio output. Then hook the other end of the resistors to the LOC input. That way, you will fix the resistance issue.

Should You Ground a Line out Converter?

Besides hooking a LOC between a factory radio and an aftermarket amp, you also need to connect it to the ground and constant power. That way, it will get the power it requires to turn on the circuitry and establish a reliable remote signal.


A line output convertor is an essential component of a car music system that uses a factory head unit. Most factory radios are not designed to output low-level signals for connection to an aftermarket amp. In such situations, adding a line-out converter helps to connect an aftermarket receiver to an aftermarket amplifier. However, if you experience problems with audio after installing a LOC, you need to know how to tell if the line-out converter is bad. That way, you will find it easier to fix the problem.

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