How to determine car speaker wire polarity

It is fantastic to listen to your favorite singer’s song while you are driving your car! We know it is very well. But if your car’s speakers are not working and you can’t listen to music, it will be very frustrating.

So it is a great demand to connect the wires to the speakers in the right way. But what if when you have found a lot of cables to the speakers, and you can’t find out the right two. It will be time-consuming and hard to sort out one by one.

So if you know how to determine car speaker wire polarity, that will be very helpful for you. To see the procedure check our content, we have discovered the process for you.

1. Speaker polarity

Before going to the step by step procedures let’s know something in detail about speaker polarity.

What is speaker polarity?

Speaker polarity is a process of connecting the wires between the speaker and the amplifier. In this process, you have to connect the positive amplifier wire to the positive amplifier and the negative amplifier wire to the negative amplifier.

When you have done the job successfully, the speaker gets the right polarity and works well. But if you have made the connection in a reverse way, the speaker gets the reverse polarity.

How does it work?

We think you are very much familiar with a microphone. Basically, a microphone and a car’s speaker works in basic rules. When the electricity goes to the microphone’s diaphragm and creates its movement in a microphone, then the sounds generate. The same thing happens in a speaker. But in this case, the electricity passes by the speaker’s wires.

The speaker stays in a default position when it does not have any connection with electricity. But, when it is connected with electricity, it gets an audio signal and starts to move outward and inward. We think you have seen this when you listen to a song on your audio player.

As it vibrates outward and inward, so it forms positive and negative changes in its pressure by displaying air particles in its surroundings. And these changes make a chain reaction to our ears by the air form of speakers

What happens when a speaker polarity is inverted to the speaker?

When you cross the wires from the amplifier to the speakers, it inverts the speaker’s polarity. It means that it moves to the inward when it should be moved outward, and it moves to the outward when it should be moved inward.

The speaker creates a sound wave, and it is exactly the opposite direction by how a microphone records the signal.

How can speaker polarity affect sound quality?

You have to invert the wires in a correct way to the amplifier, either it affects the sound quality or not. But if you make a mistake to push the cables correctly to the amplifier, the result varies depending on the situation.

Sometimes Mis-wiring doesn’t make any noticeable difference, but sometimes it may cause massive problems. There are two kinds of reversed polarity. One is one speaker reversed polarity, and the other is multiple speakers reversed polarity.

One speaker reversed polarity

When you use one speaker, then you can’t see any remarkable effects on it. In one speaker, the sound speaker fluctuates the pressure alternatively. And the speaker wire gets an alternative electrical current and makes audio signals.

During this time, every position is changed virtually and equally through opposite negative changes. That’s why you don’t notice any sound difference in the audio signal between polarity and out of polarity.

Multiple speakers reversed polarity

In multiple polarities, you have noticed a lot of effects on reversed polarity. You don’t see any virtual effects either connect the wire in the correct polarity or reverse polarity. But if you connect the wire for one speaker in a proper way and the other in a reverse way, you will notice a significant effect. If you like to observe these effects, you can use two speakers’ headphones or two speakers stereo.

But if you use a speaker with an array, you will find that one inverted polarity causes significant sound system changes. If you use full range line array speakers, which are used for live sound reinforcement, you have to make a connection in the same way.

You can also use subwoofer speaker’s arrays for inverting polarity to get a better direction. And for this, you should correctly wire it. If you make any changes in the polarity, it makes an audio console or DSP (digital signal processor) amplifier.

If your DSP amplifier or audio mixer doesn’t permit you for polarity inversion, you have to use an inversion adapter of polarity.

Does incorrect polarity damage speakers?

The sound quality changes in various ways if you connect inverted polarity. But we like to say on a positive note that thankfully it does not make any hamper to your amplifier. The correct polarity and the reverse or incorrect polarity applied voltage to the inverted polarity are the same. So your amplifier will not damage due to it. But, your amplifier does not work well though you give proper connection to the speakers.


So, it will be wise to provide a standard connection to the speakers and get crystal sound quality.

2. How to Test Speaker Wire Polarity?

Before identifying the positive and negative wire, you have to test some things. Such as

  • Set up the audio system

First, you have to set up your basic audio system with your car’s amplifier because the amplifier runs through the car’s battery.

Basically, you can set up this simple audio system anywhere on the car. But most of the car has it’s an amplifier to its radio head unit. (Radio unit is a thing that has some buttons what you can push.)

  • Text the car audio system

You have found a phone/RCA (Radio Corporation of America) cable that goes to the radio head unit beside the incoming power cable. The power cable is a basic model of integration. There also has a ground cable and a set of speakers wire to every speaker. When you look at the speaker’s wires very carefully, you will get two wires. One is positive wire, and one is negative wire; what you have to find out from those wire.

When you connect the positive and negative wire to the correct polarity, your car’s speakers will work flawlessly.

  • DC voltage measurement system with a multimeter

You have to use DC ( Direct Current) voltage settings to measure your car’s voltage on the multimeter. Because always the batteries are measured in DC voltage. As your car gets the power from the battery, so you need one of these settings. Another thing is, DC voltage is one of the best functions of a multimeter. Even your digital multimeter does not have any other settings without DC voltage.

You have to plug in your standard test leads into the multimeter to measure your DC voltage. You have to measure the battery voltage of the car to test the settings. When you hold each cable to the battery terminal, you can see around 12 volts.

3. How to determine car speakers polarity

After the above discussion, we think now you have a good understanding of a car audio system, DC voltage, and a multimeter. Now, we will tell you a step-by-step procedure for determining car speaker wire polarity with a multimeter.

1. Unplug the cable

First, disconnect the wires from the outlet for your personal safety. When you unplug, you can quickly move the wires however you want.

2. Attach the wires to the battery

After unplugging everything:

  • Take the 9V battery.
  • Open one of the speaker wire from the receiver and the speaker.
  • Warp up each receiver wire end part around the battery.

3. Test wires with your multimeter

You can see that a flow of current passes through the wire. Now, touch one of the wire with one of the test leads. If the test and the wire’s polarity match up correctly, you can see a positive reading is going on your screen. If the test and the wire’s polarity don’t match up correctly, you can see a positive reading, which means you have touched the negative wire.

If you have connected a negative test lead and notice a negative reading, you have touched the negative wire. It is the reverse system.

4. Give a remark to the wire

It is the last step of your task. Now give a marking to the positive wire with a tape and connect it to your speaker. As you can identify one wire as positive, so you can naturally understand that the other is a negative wire. Now connect the negative wire to its place.

Now turn on your car’s audio system. You can listen to a crystal clear sound from your audio system.

Final thoughts

To test the wire polarity with a multimeter, it is not an as tough job as you seem. But you need a little bit of knowledge about this procedure to do the job efficiently.

We have tried to discuss how to determine car wire polarity with a multimeter with a very easy and step by step process.

Though it is not a tricky job, you have to take your time when you work with your car’s audio system.

If you are not accustomed to car repairing work, it will be a time-consuming job for you.

Yes, you find it very hard at first, but it will be more comfortable when you start working. Even after performing this task for sometimes, you will become an expert.

Have a great experience listening to your favorite music.

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