So I got some new 6x9s to replace the factory ones (Infinity I system) in my rear deck. I got one in and decided to test it side by side with an old one in the opposite side. Individually, both the factory speaker on the left and the new one on the right put out good bass, but when played together rather than faded to one or the other, the bass goes away. I knew right away there was something up with the polarity.
Eventually, I determined that the factory 6x9 speakers have the polarity crossed up compared to the wiring diagrams and labels
. I then checked the factory 6.5" speakers that were in the front doors to see if those too were inverted and if so then I'd just assume the wiring diagrams themselves are wrong, but those DO have the correct polarity.
So that left two possible scenarios:
1. The factory speakers had the front and rear speaker pairs out of phase with each other at the speaker connection, and the wiring diagrams are correct.
2. The factory speakers had the front and rear speaker pairs IN phase with each other, but the wiring diagrams are wrong for one or the other somehow.
The answer? #1
Here's how I determined that:
Somebody gave me the idea of buying a polarity tester to figure it out, however I'm not one to spend money if I don't have to; I figured I could come up with something that worked the same by myself.
Those testers typically come with a CD with certain sound tones on it, which a microphone likely measures to see if it produces what is expected.
I created such a tone in Audacity, that should only create a 'push' and not a 'pull' if the polarity is correct.
(A pull is created for waves under the middle line; this was about a 50Hz tone, sounded like a short drum kick when played).
I then hooked my laptop up to the stereo and played it on all 4 individual speakers (FL, FR, RL, RR) to see if it sounded different on any of them, and sure enough the RL speaker sounded different than the others. I had temporarily put both new speakers in the back, but swapped the wires for the RL one, taking the wiring diagram's word on which was + and which was - (e.x. so the wiring diagram's "-" went to the new speaker's "+"); this seems to indicate that the only thing that had incorrect polarity was the original 6x9 speakers!
To verify that my ear wasn't deceiving me, I got out my phone and recorded a video. Going frame-by-frame visually seemed to correlate what I heard, and so did the recorded audio!:
Hopefully this helps anybody else that's replacing factory Infinity 6x9s. And if you aren't replacing them, you may want to go swap the wires for them anyway...