Speaker cables (+ or -)

[MKlahr]

My house has been renovated and set up with in-wall speakers in the main room. The cables have all been connected and are hidden from view coming out of the wall near my amplifier. It all looks very good. Unfortunately the person who put in the speakers (and connected the cables to them) can not tell me at the amplifier end which of the cables (for each speaker) is positive and which is negative. There are no markings on the speaker cable. Is there a way where I can find out which wire is which without having to take out all the cable and starting again. Thanks.

 

[Alex2507]

You could use a test wire (jumper) from the speaker location back to the amp location with an ohm meter (continuity tester) to identify + and -. The problem is that your speaker wire is more than likely not rated for in wall use. I would replace it with something appropriate like CL2 or CL3 rated wire. I'm not sure right off hand which is required but I'm sure a Google search would get you a ton of info. If the existing cables are not fastened to the studs, you could attach the new cable to the existing cable and snake it back through.

-Alex

 

[TLS Guy]

My house has been renovated and set up with in-wall speakers in the main room. The cables have all been connected and are hidden from view coming out of the wall near my amplifier. It all looks very good. Unfortunately the person who put in the speakers (and connected the cables to them) can not tell me at the amplifier end which of the cables (for each speaker) is positive and which is negative. There are no markings on the speaker cable. Is there a way where I can find out which wire is which without having to take out all the cable and starting again. Thanks.

Two ways you can tell. I agree with Alex though, that this is likely substandard cable.

Connect a battery to one end of the cable. Mark the positive connection. Put a meter across the other end of the wire. Mark the wire connected to the red lead that gives a positive deflection of the meter.

The other way is to have an assistant make or break a connection to a battery one end, marking the positive connection. Attach a speaker to the other end. Mark the wire positive that is connected to the speaker, when the first movement of the cone is outward, when the connection is made.

 

[highfigh]

My house has been renovated and set up with in-wall speakers in the main room. The cables have all been connected and are hidden from view coming out of the wall near my amplifier. It all looks very good. Unfortunately the person who put in the speakers (and connected the cables to them) can not tell me at the amplifier end which of the cables (for each speaker) is positive and which is negative. There are no markings on the speaker cable. Is there a way where I can find out which wire is which without having to take out all the cable and starting again. Thanks.

If that person actually charged money for this, they should A) know that the electrical code requires that proper cabling be used, B) know that polarity matters when connecting the speakers and C) come back and identify the wires for you, possibly replacing the wire they installed. Lamp cord from Home Depot is marked- I can't imagine where this stuff came from, or how old it is.

Strip off some of the insulation from both conductors, to see if one is silver and the other copper. That's how some manufacturers have differentiated them.

CL-2 and CL-3 are both appropriate for in-wall use. Plenum rated cabling without PVC is made for runs that pass through HVAC returns (not usually through ducting, though).

 

[Adam]

Another way to check is to hook up the amp/receiver and do a phase test. Some receivers have that built in - they'll check to see if you have the wires hooked up correctly or if they are reversed.

 

[Alex2507]

If that person actually charged money for this, they should A) know that the electrical code requires that proper cabling be used, B) know that polarity matters when connecting the speakers and C) come back and identify the wires for you, possibly replacing the wire they installed.

Do you really think an electrician ran those wires? Something tells me the guy doing the work was hardly getting paid enough to work, nevermind know anything. I also have to wonder about the guage of the wire.

Another way to check is to hook up the amp/receiver and do a phase test. Some receivers have that built in - they'll check to see if you have the wires hooked up correctly or if they are reversed.

I'm not 100% about this but I have a vague idea that getting the speakers in phase is not the same thing as having correct polarity. I'm only bringing it up in hopes of having it clarified now that the subject is on the table.

 

[TLS Guy]

Do you really think an electrician ran those wires? Something tells me the guy doing the work was hardly getting paid enough to work, nevermind know anything. I also have to wonder about the guage of the wire.



I'm not 100% about this but I have a vague idea that getting the speakers in phase is not the same thing as having correct polarity. I'm only bringing it up in hopes of having it clarified now that the subject is on the table.

In terms of speakers it is the same thing. However I would never trust receiver software to get it right.

The convention is that with a battery positive to positive and negative to negative, the cone flies forward. If the polarity is reversed then the speakers are 180 degrees out of phase.

 

[Alex2507]

In terms of speakers it is the same thing. However I would never trust receiver software to get it right.

The convention is that with a battery positive to positive and negative to negative, the cone flies forward. If the polarity is reversed then the speakers are 180 degrees out of phase.

It might help to mention that a AA or maybe a AAA battery is all that's needed. I knew that trick but forgot that I knew it. Somewhere along the line I heard that the positive should go to the cap on a coaxial car speaker. Be that as it may, I'll take your word for it.

Speaking of convention, when you do get the dark and light colored conductors in a speaker wire, which is used for positive? If I knew the convention, then I could just do it that way from here on in.

 

[highfigh]

Do you really think an electrician ran those wires? Something tells me the guy doing the work was hardly getting paid enough to work, nevermind know anything. I also have to wonder about the guage of the wire.



I'm not 100% about this but I have a vague idea that getting the speakers in phase is not the same thing as having correct polarity. I'm only bringing it up in hopes of having it clarified now that the subject is on the table.

Why would an electrician be the first choice for your question? Stereo shops are full of people who think they know all about how to wire this stuff, even though they barely know how to plug it in. Also, in my experience, unless the electrician has actual interest or training in A/V wiring, they shouldn't bother. They seem to like running everything along side the power wiring, usually bundled together and the range of bad cabling choices I have seen used by them is incredible. While some places require all wiring to be done by licensed people, it could have been a friend doing it for a low price, someone doing a side job or a builder with "a guy who's good with this kind of stuff".

Speaker wires are marked for polarity- the sound from speakers is in or out of phase. If a positive pulse at the source results in a negative pulse from the speaker, the polarity has been reversed, somewhere. In AC voltages, phase is important.

 

[highfigh]

It might help to mention that a AA or maybe a AAA battery is all that's needed. I knew that trick but forgot that I knew it. Somewhere along the line I heard that the positive should go to the cap on a coaxial car speaker. Be that as it may, I'll take your word for it.

Speaking of convention, when you do get the dark and light colored conductors in a speaker wire, which is used for positive? If I knew the convention, then I could just do it that way from here on in.

If a coaxial speaker has a cap(acitor), connect the battery + to the terminal connected to the cap if the terminals are the same size. Most car speakers use two different sizes for the speaker terminals and they're often marked. If it's not marked in any way, the battery will make the cone move outward with the positive terminal connected to the speaker's positive terminal, as TLS stated.

If you have two conductors of different colors, it really won't matter which is positive, as all are wired the same way. Electrically, I seriously doubt that the cable will react differently. If the colors are white and black, the white is usually positive.

Often, Red/Black is R+/R- and White/Green is L+/L-, although I have seen blue substituted for green.

 

[Ttom]

My house has been renovated and set up with in-wall speakers in the main room. The cables have all been connected and are hidden from view coming out of the wall near my amplifier. It all looks very good. Unfortunately the person who put in the speakers (and connected the cables to them) can not tell me at the amplifier end which of the cables (for each speaker) is positive and which is negative. There are no markings on the speaker cable. Is there a way where I can find out which wire is which without having to take out all the cable and starting again. Thanks.

You have in wall speakers but don't they have a grill over them? Seems like you should be able to remove the grill and take out one speaker to see how it is wired, that is assuming you have silver and copper colored wires.

Also if you don't have CL2 or CL3 you just may need to start over as was mentioned above.
If you don't know the type or gauge of wire you have cut off a short piece, go to a local audio shop or Radio Shack and find out what you have.

 

[Rickster71]

As others have already mentioned; it sounds like the installer didn't know what he was doing.

Wire that has UL approval will have a surface marking of some type.
Whether it's imprinted on, or stamped into the jacket, or has raised ribbing; it will be marked in some way.
Some will have a few fine fabric strands inside, wrapped around the wire strands.
The markings indicate several things about the wire. i.e. - Temp rating, voltage, sunlight resistance, etc. (too many to list here)

Those markings can be used to maintain a marking convention for polarity.

Rick