question about speaker polarity

[redlightrich]

hi all, does anyone know if it is possible to check the polarity of the audio systems speaker leads with a dvom? if so how? i have the wiring diagram, but being the stereo was previously modified, i can no longer trust the wiring diagrams accuracy. thanks, rich.

 

[Steamroller]

I am not aware of how to use a DVOM for testing speaker polarity, but I do have a solution:

1. Ensure that the speaker lead points you have access to go directly to the speaker only. That is, be sure that the leads go only to speaker, and that they do not tie into any other wire harness, power point, etcetera.
2. Get a 1.5 VDC battery (i.e, a "C" size).
3. For a brief moment, touch the "+" side of the battery to one speaker lead, and touch the "-" side of the battery to the other speaker lead.
4. If the speaker cone moves out (i.e., away from the speaker magnet on the back of the speaker), then the speaker lead going to the "+" side of the battery is the "+" side of the speaker, and the speaker lead going to the "-" side of the battery is the "-" side of the speaker. If the cone moves in (i.e., towards the speaker magnet on the back of the speaker), then the speaker lead going to the "+" side of the battery is the "-" side of the speaker, and the speaker lead going to the "-" side of the battery is the "+" side of the speaker.

 

[JDR]

Monster, $149: http://www.monstercable.com/productPage.asp?pin=534

Alternative brand, $109:
http://www.davidnavone.com/detail.asp?PRODUCT_ID=N-PD-9

Free:
You can do it by ear (and feel)... put in a CD with a SOLID BASS sound. Play just the rear speakers, if your speakers are out of polarity they'll cancel each other out and make light thumps, if the are good, you'll get good hard thumps. Then do the fronts, and then just the left (or right). Fronts are more difficult, as crossovers naturally cut down most of the base, so in and out of phase will be very subtle. In the end they'll all be either right or 100% reversed... either way they will ALL be "in phase" which is what really you're looking for.

As for using a volt meter... now a days most stereos use floating grounds on the speakers, so you can't measure the difference to the car's chassis any more.

As for Steamroller's way, I've used that way too. Do you at least know the wiring coming out of the head end (amp)?