Does Anyone have a method for figuring out correct polarity to a speaker when the wire is unmarked?

For example;

You are on a job done by another company years ago. The previous owners of the house sold the home complete with speakers in every room and a mess of tangled wire in the family room closet.

They call their local A/V shop (you) and agree to your price to activate the dozen or so pairs of speakers.

Your guys get there and realize that in addition to every wire being unmarked, The wire ran is like some sort of lamp cord with no indication of + or - on the wire.

Lets assume that the wires cannot be run again. Is there a way other than removing every speaker and toning one wire to check for polarity?

I have heard of a battery trick but I am skeptical if that really works. I know polarity to some is irrelevant at a time like this ( above scenario ) but for the passionate installer who wants to give the best quality this could be a nightmare.

Thanks

9VDC battery and multimeter.

Battery on the amp end and meter on the speaker end.

Dave

Thanks for the response.

I was wondering how to do it without removing the speakers though

If the MID/Woofer moves forward you have the correct polarity + to + and - to -.

I also have a test CD and a polarity checker from Richard Clark around my office somewhere if you need to check absolute polarity.

Do you mean with the battery? will this work more than once?

I suppose this has to be checked with the grills off.

Negative on the 9 volt - use a 1.5v cell ie AA

A 9 Volt is fine, you cant push enough amperage from a 9v battery to damage a speaker.

Heck, I've used a 14.4V Cordless drill battery before to pop speakers........

You won't have to disconnect the speakers to use this method, but you might have to remove the grilles. That can be worse.

The 9 volt battery won't hurt the speakers, in my experience. You will have a problem with some smaller speakers, though, that have a capacitor to keep bass out of them. they will respond once, then you will have to short the speaker leads to get another response. And these small speakers often have grilles that are not removeable.

If you are testing the small Bose speakers, I suggest connecting them to 120 volts AC from the wall. This will not detect their polarity, but it will give you a good reason to recommend their replacement.*




*newbies: this is a joke. 120 V will fry almost any speaker in one VERY LOUD instant and AC won't tell you a thing about polarity.

yes
hire a PRO

If it's not possible to remove the grilles, you can try using painter's tape to cover the grilles with plastic wrap (ie Saran wrap). When the battery makes contact, the woofer's movement should either bulge the plastic out or suck it up.

Is the entire house done without VC's? Most likely there are volume controls in each room. just remove the VC and test from there. unless of course they didn't hook up the VC right the first time.

There is no difference in the wire? Usually there is some indicator. Like a string ran with the wire or tiny ridges on one of the wire or something.



What about attic access? there isn't any access to the rear of any of these speakers?

Deb Has good idea, we generally use a piece of solder, any piece of wire, thru the grill , gently in contact with cone, pop spk and wire will jump forward or not .

Please be careful with using anything over a 9volt battery!!!!!!!!!!!!!!! Big Dewalt, Makita, etc batteries will blow tweeters. Been there and done that. Polarity testing devise is the best but most expensive. Richard Clark has a system as well as Rockford Fosgate. Good luck.

The trouble with even marked cables is you can't tell if the previous installer paid attention to it. Especially true with lamp cord - it always has a ridge on one side of the cord, but the kind of guy who would use that probably wouldn't bother with polarity, so plan on checking it.

JMK, a 14.4 battery won't fry the tweeter, since a capacitor is in series with it. The capacitor is often "the crossover" in a cheaper speaker and a capacitor blocks DC from ever getting to the tweeter.

14.4 volts on the other hand will go straight to the woofer, and that battery has *plenty* of current to fry the voice coil of the woofer.

We always use a AA battery - gives plenty of pop and cheaper than 9v batteries!

BTW, the saran wrap trick and the solder trick are excellent.

Minor correction here. The entire time the capacitor is charging, current is flowing through the tweeter. Once the cap is fully charged, then current flow stops.

That said, we have been using 14 v drill batteries for a great many years.... never had one tweeter to blow.