# Testing speaker cable polarity with multimeter



## SPAZ (Jan 7, 2009)

Hi,

The installer did not label the wires going to the tweeter from the amp. Is there an easy way to measure the wire polarity using a multimeter?


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## ckirocz28 (Nov 29, 2017)

SPAZ said:


> Hi,
> 
> 
> 
> The installer did not label the wires going to the tweeter from the amp. Is there an easy way to measure the wire polarity using a multimeter?


No can do with AC. You can test speaker polarity with an app.


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## timps67 (Dec 29, 2012)

You're trying to figure out which wires go to which tweeter? Disconnect 1 set at a time at from the amp and see which tweeter stops playing. The speaker wires should have a mark to show which side is + or -. 

If for whatever reason you still need to figure out the polarity but know which wires go to which speaker, disconnect the speaker wire at both ends, get a long piece of wire use it as a jumper to test for continuity to each side of the speaker wire. One lead on your meter goes to the amp side of the wire and the other end to the speaker side.


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## ckirocz28 (Nov 29, 2017)

Sometimes the wires have a ridge, or one side is square, or they have writing on them. Usually, if there isn't a + or -, the odd one is positive (the square, ridged, or writing), the round or blank one is negative.


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## Justin Zazzi (May 28, 2012)

All good stuff, and there is another trick if you need more:

If you can see the tweeter, even a little bit, try connecting a 9V battery to one pair of wires. If the tweeter moves outward toward you, that's the correct polarity where the + on the battery is connected to the positive wire. The tweeter will move a very small amount, sometimes it's hard to see unless you're looking really close and you might have to connect the battery rapidly a few times to see it.


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## mumbles (Jul 26, 2010)

^^^^ This


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## thornygravy (May 28, 2016)

Safest way is to use an app or a polarity tester.


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## bluesman1 (Mar 2, 2010)

thornygravy said:


> Safest way is to use an app or a polarity tester.


This^^.

If you don't have an easy way to, or don't want to use a phone app, a polarity tester with CD is all of about 10 bucks on amazon.


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## Mullings (Jan 31, 2016)

Just set the multimeter to continuity and if there a tone setting ( this is when it beeps when there’s continuity) turn that on then Test from tweeter side and amplifier side for correct wire.


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## Justin Zazzi (May 28, 2012)

thornygravy said:


> Safest way is to use an app or a polarity tester.


Do you believe using a small battery is not safe?


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## bluesman1 (Mar 2, 2010)

Battery is pretty much safe although, personally, I wouldn't use a 9V on a tweeter.
Problem with the battery is you have to be able to see the speaker cone. Second problem is, with tweeters, it can be difficult to see the dome move. Also, if passive crossover are in line, the capacitors will block the DC. But battery is ok otherwise.
Battery is also good if you are checking wire runs at opposite ends of the vehicle where you can't meter both ends of the wire. Just clip a battery on one end and check polarity at the other and then label the wires at each end. 

A polarity tester is much easier when the system is already hooked up. Some phone apps work like a polarity tester where you can play a test tone and use the phone near the speaker to check polarity. Some allow you to plug a 1/8" plug into the phone and wire the other end direct to the speaker wires.


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