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Can I use a voltmeter to determine polarity?

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Old November-2nd-2003, 07:03 PM
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Can I use a voltmeter to determine polarity?

Hey all!

I've had this long standing issue with not being sure if I had correctly installed all my speakers. I want to know the easiest way (or the best way) to determine the polarity of the speaker wires in my '97 Protege LX.

I thought of using a digital voltmeter to check the polarity, but I am not sure if that's possible. Someone suggested to me the idea, but never explained how it's done. What I did was this -- I take the positive lead of the DMM and hook it up to what I presume is the positive speaker wire, then I hook up the ground lead to the negative speaker wire and if the DMM shows a "+" in front of the voltage reading, then the polarity is correct. If it shows a "-", then I have to reverse the polarity. Does that make sense?

Well, apparently that doesn't work all the time. I tried using this method on my rear speakers and when I tested them, there was almost no bass. Having only one speaker ON gives a lot more bass than having the two of them. Then I reversed the polarity on one of them and the low freq's magically returned.

So, how can I determine the polarity of those damn speaker wires using a voltmeter (or anything else)?

Thanks a lot!

P.S. Where is the Car Audio section of the forum??
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Old November-2nd-2003, 09:36 PM
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Can I use a voltmeter to determine polarity?

Apparently not...

I found this on another forum:

The voltmeter won't be of any use since Alternating Current has no POLARITY.. it only has PHASING. The voltmeter on the AC setting won't give you a + or - indication. AC is constantly changing between positive and negative.

You'd need an Oscilloscope to check the phasing.
So, does anyone have the colors for those speaker wires?
Is there a way to test for polarity?
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Old November-3rd-2003, 11:29 PM
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Well, if anyone's interested, the speaker wires on the '97 Protege are these:

Front Door (Driver) - Violet (+); Blue/Brown (-)
Front Door (Passenger) - Yellow/Blue (+); Violet/White (-)

Rear Dash (Driver) - Orange(or Brown) (+); Yellow (-)
Rear Dash (Passenger) - Green/Black (+); Green/Brown (-)
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Old November-14th-2003, 08:26 AM
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Yup. It is standard to switch the wires on one speaker if no bass is present.
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