Use multimeter to determine polarity on speakers while playing?

[onefstfoknv6]

Can you use a multimeter to determine polarity on wire that is unlabeled (potentially while music on)? Wires were connected to factory rears to run to amp high level in. Those bare wires will power a test 5x7, just unsure of polarity when wiring my high level adapter.

 

[keep_hope_alive]

if the signal is unbalanced, you could try measuring AC voltage relative to chassis ground on each wire. Likely, both wires will have voltage (similar to a bridged output) and the DMM won't be able to help.

You could, however, assume the existing speaker is wired correctly and then disconnect it and use an AA battery to test polarity on the speaker terminals - which would infer what wire is "positive".

You can also assume the speakers are made consistently so pay attention to the connections and be consistent as you snag left and right to sum at the sub amp.