How to Add RCA Input to Factory Radio (SOLVED)

Norvan Martin
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An RCA jack is a signal carrier commonly used for carrying audio and video signals from one device to another. Using RCA input is one way to manually connect an aftermarket external car amplifier with a factory stock car radio system.

However, dealing with a factory radio poses the challenge of adding an RCA input because most of these radios don’t come with an integrated RCA input. However, you can add RCA inputs by attaching an RCA adapter converter box or line output converter. We explain below.

Quick Step-By-Step Guide

Below is a quick look at the step-by-step guide:

  1. Carefully remove your car stereo from the DIN slot
  2. Disconnect the speaker wires on the rear channels
  3. Connect the speaker wires to the two sets of input terminals on the RCA converter box or a line output converter like the PAC SNI-35 Variable LOC Line Out Converter.
  4. Attach the RCA cables to the jacks and run the wire to the amplifier. You may have to remove carpets and such for this. You will need long cables like the KabelDirekt – 25ft Long – RCA/Phono Cable, 2 to 2 RCA/Phono, Stereo Audio Cable
  5. Connect the RCA plugs to the input sockets on the amplifier. 
  6. Tune the gain control accordingly as this will prevent any distortion.

This is explained in more detail below, but first, let’s talk about the converter box.

What Is an RCA Converter Box?

An RCA converter box or line output converter is used when adding an amplifier to a factory radio to convert the radio’s speaker level output to the lower amplifier (RCA) level input.

This means that it will take the high-level signal from the radio’s speakers and convert it into a low-level output that is compatible with any car amp.

Please note that the sound quality you gain from this will not be the same as installing a high-end aftermarket head unit. However, you can find some good options out there that will do a good job. A good example is the PAC SNI-35 Variable LOC Line Out Converter.

Step1: Remove the factory car stereo from the slot.

  1. For safety reasons, the first and most important step when performing any upgrade or removal on your car is to disconnect the battery from the terminals. This is to prevent accidents that could be detrimental to the parts of the car or even to the person. However, this should be done by removing the negative wire first and then the positive, ensuring that they don’t touch each other. The positive wire can be identified as a black wire or by locating the wire with a plus (+) sign. The negative is red or with a minus (-) sign.
  2. Most factory-fitted radios come with a cover known as the “stereo trim.” This is a plastic covering that forms part of the interior design and holds the radio in the slot. Remove this plastic trim by unscrewing it from the dashboard. The screw is mostly located safely in a part that is hidden from the naked eye, although this is always toward the bottom of the trim.
  3. After removing the screw, separate the trim from the dashboard by using a flathead screwdriver. Remember, these are factory-fit, which means they might be hard to separate. However, be careful with the force you add not to break the plastic.
  4. Removing the car stereo should now be easier. Although this might depend on your type of stereo, the stereo should have between 2 and 4 bolts holding it down in place. Unscrew the bolts to slide it out.

Step 2: Separate the wires from the radio’s rear channel.

  1. Most of the time, you might find that it is still difficult to bring out the stereo even after unscrewing it. This is because of the antenna wire. Most often, this wire is short, and that might be responsible for the difficulty. Hold the stereo out with one hand and use the other hand to disconnect this antenna wire.
  2. There are other couples of wires you will also need to disconnect from the back of the stereo. The common ones are the speaker wires and the power wires. Gently disconnect these wires from the rear of the radio without damaging it. The best way to ensure this is by removing the wires one at a time and holding the wire with one hand and the stereo with the other hand firmly.

Please note: it is important to note where you remove each of these wires to make it easier when you have to put them back.

Step 3: Connect the wires to the RCA converter.

  1. Before connecting the wires, the first step to take is locating where to mount the converter. This might sound strange, but as a non-professional, the best way to save wastage is to first find out where you want to put the converter. This step will be able to guide your selection of how long the wires will be.
  2. Run a wire from the position you have chosen to mount the converter to your head unit. The dashed box behind the head unit might not be an ideal position for the converter because it might cause discomfort when putting the stereo back in.
  3. Connect the wires to the splice bar of the converter and place them where you have decided.

Step 4: Attach the cables from the RCA cable to the jacks and run down the car

Next, connect the RCA cables to the jack and run it from the converter down through the headbox. This should come out through the box to the engine unit to make it easier to connect to the amplifier.

Step 5: Connect to the amplifier

To get your speaker working, connect the wires to the amplifier to power it. Now you can test to be sure your connection is working.

Fix all connections back and replace the stereo in the dashed box. Fix it all the same way you removed it. Everything should work perfectly now.

Please note: To prevent the converter from producing a rattling sound when the car is in motion, you can screw it down or tape it to a surface to hold it in place.s

RCA Adapters for Stock Radio

Connecting an amplifier without speaker-level inputs to an amplifier with no preamp outputs is made possible by using the RCA adapter that comes with the receiver. An example of this is the LOC2S amplifier add-on RCA adapter.

Speaker to RCA Converter

These are adapters that convert audio signals from an electronic device to a speaker-level output. This adapter is compatible with smartphones, multimedia players, tablets, and so on. An example of this is the “CESS-064-1f Speaker Cables to RCA Plugs Adapter”.

Car Stereo RCA Output

As long as your head unit has RCA outputs that work, an amplifier can be added to your stereo. This makes it possible for audio signals to reach the amplifier and be turned into powerful signals that can drive the car speakers. Otherwise, you will only get low-quality sounds or no sounds at all.


1. Can I use any RCA input for my car?

It depends! Knowing the exact type of RCA that works best for your car may be the only help you will need. However, in most cases, you can easily get this help at no cost by asking the seller which RCA would be best for you.

2. Can I use RCA input without an amp?

No! RCA cables are used to connect amplifiers to speakers and vice versa. Therefore, thinking of using an RCA cable without an amp may defeat the purpose of using an RCA input.

3. Are RCA converters expensive?

That will depend on your definition of “expensive.” But, in a truer sense, an RCA converter only costs a couple of bucks to a few hundred dollars.


Adding an RCA input to your factory radio might look like a task only a professional should attempt, but when you look at the importance of having an RCA cable to the factory radio, almost everyone should be able to do it. The steps in this article should guide you to fixing one in your car when the need arises.

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Norvan Martin is the founder of He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin