Testing polarity of speaker wire coming from HU

[mordant80]

Alright, I had asked my friend to help replace my speakers. There was no label for polarity so he decides to check the polarity of the speaker wire coming from the HU he's gonna set a multimeter to ohms and put one end of the probe on one the the speaker wires from the HU and the other probe on chassis ground (a bolt in the door) In my head I cannot see how this would work as the negative speaker wire isn't ground! Anyhow, I decide I'm gonna look up a diagram just to be sure as I don't understand how he's coming up with his answer. Well he won't talk to me know because I "don't trust him" and had to comfirm. Anyhow, is it even remotely possible to figure out the polarity of the speaker wire off the HU like this? I just can't make it work in my head.

 

[Mid_Life_Crisis]

Depends on the H/U. Pretty much everything made these days has a floating ground for the speakers. In the old days you would find systems that worked like your friend is thinking, but I haven't seen one in a loooonnnngggg time.
What is the H/U? Can you look it up on the manufacturer's website?

 

[mordant80]

It's our stock HU. I got it, looked up a diagram. Isn't + and - on this simply phase and has nothing to do with ground?

 

[Mid_Life_Crisis]

It's our stock HU. I got it, looked up a diagram. Isn't + and - on this simply phase and has nothing to do with ground?

Modern speakers are floating. The - is not tied to ground. You can safely consider it as a phase reference, although the Bose unit has a funny ground system, so I would try to observe polarity if you are connecting to an amp and make any polarity changes on the speaker leads. Just to be safe.

 

[mordant80]

Thanks for the info