How to determine phasing on speaker wiring.


Mark Senn
Could someone please tell me an easy way to determine the proper phasing (+ or -) of the speaker wire (inside a wall) in a pre-wired HT system that does not have color-coded wire?

John A.
For each pair of wires, take one strand at one end and see which strand at the other end will complete a circuit with a simple battery and flashlight bulb, bell, or whatever you have handy that works off a battery. When the light comes on, or the bell rings, you have an electrical circuit. Mark the casing on that strand at both ends; it is one continuous wire. Use it to connect either - to -, or + to +.

Mark Senn
John, I'm a bit confused. Don't you have to connect to both the positive and negative ends of a battery to make a complete circuit and to get the "light to come on"? How can I do that with one strand on one end attached to the battery and one strand on the other end attached to the "light"? I apologize for not understanding.

I am assuming that you already know which wires go to which speaker and all you need to know is which one is negative and which one is positive. Here is one way to find out. If you can access the speakers at all or at least see the cones, it will be easy.
Take a small 1.5v battery and connect it to the wires in question, connect one end to the positive(+) and the other to the negative (-) side of the battery, don't do it for a long time, just enough to observe movement on the speaker cones. Observe the cones of the speakers, if the cones get pushed or moves out, take note of the polarity of the battery because now you know which is which. Now if the cones, move inward or it gets sucked in when you apply voltage, then it's backwards.

John A.

You've got it. Yes, you need some more long wire to complete the circuit. The circuit goes battery positive -> cable -> light -> battery negative. You can put the extra connector in place of any arrow. If the light comes on, you have identified both ends of one strand of cable. That is all you need to know.

Mark Senn
Thanks, John and Berny! I love this discussion group.

John A.

You're welcome. Hope it helps. The insulation really should be marked. Maybe the previous users just guessed, and got bass cancellation, the main effect of having speakers out of phase.

I have the same issue and the answers above does not really answer the original question. I have 6 home run speaker wires (pairs) that run from the ceiling in a church and are inaccessible (very high) and there is no marking on the wires that would suggest polarity. What is needed is a way to determine leg goes to the + and which to - with nothing to work with but the wires and not the speakers.

Drag your finger nail across the wire. The one with the ridges can be possitive.

Most wires are marked with little black plusses, white lines, one (one of the paires will be shaped like a box) or several ridges or slightly different color conductor.

If none of these exists use a AAA battery and a cheap battery tester from Radio Shack. The little needle will let you know the polarity. You will have to mark each pair one at a time though.

Hope this helps.

John A.

All you need to know is which are the two ends of a single wire of each pair. There is no difference in the wires themselves: you just have to make sure + (speaker) is connected to + (receiver) and - to -, for each channel. My replies to Mark will do it. You may need one extra cable to complete the circuit if the two ends of speaker cable are far apart.

Unregistered guest
I need to hook one end of my speaker wire to my ONKYO reciever and the other end to my Audigy sound card. The problem is that the sound card has RCA connectors and the reciever has screw lugs ( red/black). Which is the + and - on the RCA plug. Is the pin portion of the plug the positive line ?

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