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Online stereo wiring diagrams reverse speaker polarity!!

kloker

NAXJA Forum User
Location
Austin, Texas
Has anyone noticed this? Well, I have. Here are the details. I just picked up a new head unit for my '97 XJ Sport, which came with the stock four-speaker system, front 5.25s in the doors and in the soundbar molded into the rear headliner. The new unit is a Pioneer DEH-7800MP. Fry's lowered the price about a hundred bucks on it, and I like the 6800, which I have in my Civic, so I thought I'd step up a notch for almost the same price. I picked up a Metra mount kit (99-6501) and harness plugs (Metra 70-1817) there also. I got home and started looking at the similar plug set I pulled out with the old crapola unit, and it seemed like it was wired wierd compared to the info on the Metra package. But the kid I bought the XJ from wired it, and did say he didn't do it right. But it did have sound coming from it, so I hope the speakers are okay, so I can run 'em for a while till I can get the amps and new speakers. I'll be using MB Quart 6.5" components, haven't decided on the amps yet. Anyway to make a long story, well, a little less long, I started looking on here for links to wiring diagrams.

To start with, my FSM color coding does not match what's in my harness. Some wires are the same but some are not. And in some cases neither do any of the other diagrams I found show the same. But I noticed this: The Metra plugs show speaker polarity the same as the FSM, but the wiring diagrams at the links for Install Dr. (http://www.installdr.com/Harnesses/DCP-Wiring.pdf) and Jeep Stuff (http://snowboard247.blogspot.com/2005/05/1984-01-jeep-cherokee-xj-wiring-info.html) I found here reverse the speaker polarity! The info in those two actually switch the positive and negative leads for at least three speakers, compared to the other diagrams (Metra and FSM). You can compare them for yourself. WTF? So which is right? I guess I'm about to find out, when I install the unit today. I'll post back up what I learn. But I will say that the Metra kits I used on My Civic and several other cars were correct. Of course, when I install amps and use the pre-outs, this will become irrelevant, but I'd still like to know WTF, eh?
 
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Reversing is OK as long as they are all reversed -- consistency is the important thing.

xjradio.gif
 
The only time overall speaker polarity is relevant is if the speakers or inputs to a speaker-driven amp use chassis ground. That's rarely if ever done these days, because most head units and amps require floating speaker outputs. My 84 Colt Vista used chassis ground for the negative, presumably to save on wire, and I had to get a special isolater for an aftermarket cassette player that required separate negative lines for the speakers.
 
This is what they have over at the12volt.com which I have used before for my 00' XJ... for a 97' XJ this is their wiring diagram for stereo...

1997 Jeep Cherokee Stereo Information​

Constant 12V+Pink/Yellow
Switched 12V+ Red/White
Ground Black
Illumination Orange/Brown
Dimmer Black/Light Blue
Antenna Right Front
Front Speakers 5 1/4" Doors
Left Front (+) Dark Green
Left Front (-) Brown/Red
Right Front (+) Purple
Right Front (-) Dark Blue/Red
Rear Speakers 5 1/4" Rear Deck
Left Rear (+) Brown/Yellow
Left Rear (-) Brown/Light Blue
Right Rear (+) Dark Blue/White
Right Rear (-) Dark Blue/Orange
 
If in doubt, hook a multi-meter to the speaker wires on the DV volts setting and check them that way. Once the meter shows positive volts, you've identified the correct polarity. That's the easy way to do it without a wiring diagram. It is important to have the polarity set correctly to the speaker for proper bass.
 
Matthew Currie said:
The only time overall speaker polarity is relevant is if the speakers or inputs to a speaker-driven amp use chassis ground.

Right -- Its worth pointing out that they all should be the same. If you reverse one speaker relative to the other they will be out of phase and it will muddy your bass.
 
so, basically, if you take a speaker and cross the wires, you'll be reversing the polarity and it muddies up the bass? just tryin to clarify for myself...
 
5spd_xj said:
so, basically, if you take a speaker and cross the wires, you'll be reversing the polarity and it muddies up the bass? just tryin to clarify for myself...

More or less. It won't muddy up the bass as much as simply to make it disappear. It's a matter of wave physics, not electronics. Take two speakers, which are putting out the same signal. If the two push and pull in sync, everything is fine. If you reverse the polarity of one relative to the other, then one will push when the other pulls, and when the waves meet, they will tend to cancel each other out. With sound systems, the lower frequencies have the least stereo separation and phase difference (the low bass is essentially monaural even in stereo, which is why you only need one subwoofer), so they are the most susceptible to audible cancellation. Putting speakers out of phase won't cause any harm. It will just sound thin.
 
If one speaker pushes at exactly the same time that the other pulls, it will create a noid. Two non-mono waves are only fully coherent with each other if they both have exactly the same range of wavelengths and the same phase. The only reason that people think they need only one subwoofer is that most every song ever recorded has the panpot fully adjusted into the up right position. No bass signal (500k or below) is ever panned to the left or the right. if it was it would take up twice the amount of head room for the piticular track that it is being recorded/mixed to. The only way to ever create a total noid is to put the "audio signal" or electrical signal out of phase in the mixing console or somewhere before the the end of the audio chain. The bass wave form is simpler than the higher freq. Thats about it. Oh yea I am an audio engineer.
 
That's what was worryin' me, that I'd end up with muddy sound, since it appeared that the diagrams I was looking at reversed the polarity on 3 speakers but not the 4th. Anyway, after a lot of checking, I ended up going with the Metra adaptors using their color coding, and it came out good. The little 5.25" Infinitys are all okay, and it will do nicely until I get the suspension done and am ready to buy amps and speakers. Then I'll run all new wire. Thanks for your help, everybody. I learned some things. I'm sure I'll learn even more when I do the upgrade. I know that'll be interesting, since it'll be my first time with that too. In the meantime I have some tunes. Beauty, eh?
 
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