I am questioning the polarity of the front door speaker wiring and it's driving me nuts. I have read the yellow w/red stripe is the positive wire but that does not seem to be true. I have the Crutchfield speaker package for a 2003 Mini Cooper S Polk Audio DB652, Scosche mounting plate and Metra wiring harness 72-9301. I have bench tested the OEM speaker with AA battery to determined the polarity of the two spade connectors by seeing the direction of the cone travel. I will refer the two spades as being horizontal or vertical as pictured. In the attached photos you can see the connector in the door as well as the OEM speaker (spade connectors polarity marked) The Mini connector clearly has the vertical female connector (which is yellow/red) plugging into the negative spade on the speaker. If the 72-9301 harness is plugged into the door connector it will give me the white positive wire (with large female connector for speaker) on the neg side of the OEM wiring. The negative should be black and have the small female connector to go to the DB652

I am not a electronics guy but I did a little googling & saw how to test the wiring polarity with a multimeter- With the 72-9301 connected to the door's wire connector - This puts the white wire on the vertical spade and the black wire on the horizontal (so to speak). Using the 200m scale V DC
Positive lead on white wire and negative lead on the black wire I get a reading of -13.9 (that is minus)
Positive lead on black wire and negative lead on white I get 13.9
Does this confirm that the OEM speaker is connected correctly ? And that the vertical spade is indeed the negative speaker wire.

If true - my wires will indeed be wrong for the DB652 White wire with large connector is negative
It's all Backwards! Am I missing something ??

 

I would be inclined to trust the wiring diagram instead of whatever you’re doing with that multimeter. I expect you’re just measuring a floating voltage.

Is there any particular reason you don’t believe the wiring diagram, and how did you determine the stock speaker polarity? I realize you said you used a battery, but I’m fishing for the answer of exactly how you went about it. The cone should move outward if the battery orientation is correct, IIRC.

 

Well because the yellow wire with red strip if clearly going to the negative terminal on the speaker - see it ? You are correct on the battery orientation. Negative on the marked spade in the photo gives me cone moving up. 1.5v battery is enough to see movement. It is a known speaker polarity test.

 

With is the multimeter procedure I used

To test the car speaker wires using a multimeter:

• Remove the car door paneling so you can access the speaker.
• Remove the speaker from the car’s internal wiring and set it aside.
• Grab your multimeter and turn it to the 200-millivolt setting.
• Attach a lead to each wire inside the door.
• If the numbers on the multimeter are positive, make a note as to which lead is on which wire. Connect the positive (red) and negative (black) wires from the speaker to these wires from the sound system.
• If the numbers on the multimeter are negative, you have the leads on the wrong terminals. Simply switch the leads on the wires to get the correct positive and negative wires.

 

Negative gives you the cone moving up? Like you touched battery positive to that?

I assume you have the amp on and playing music when you check with the multimeter?

 

Negative from the AA battery to that marked negative spade and positive to positive gives me cone going up. Bench tested - not in car.
Radio playing while test preformed.

 

So presumably since you’re on a 200 mV scale, you’re measuring the waveform average (which is ~0) instead of RMS.

Personally, I would just hook things up as-is and see if it sounds right. Worst that happens is one speaker is 180° out of phase.

 

I did a bit of digging. Apparently BMW is known to do weird things with speaker wiring for some reason. Having briefly skimmed that thread, I now don’t actually have a great explanation.

 

If it’s the factory radio with no wiring harness modifications or repairs, I would go by the factory door speaker and assume the Metra harness was backwards. Or I would do the battery test from the radio side of the harness to see which should be positive and negative by the time it they end up at the speaker.

Another radio playing test would be hooking up a speaker you don’t care about, or can’t be damaged with small particles getting where they shouldn’t be, face up and placing a few grains of rice on the cone. Then play something with a good beat to see if the rice pops up with each hit.

 

@RB-MINI , you realize that your rice test will have the same result regardless of polarity, right?

 

I thought the the force of the cone travel would be opposite depending on the polarity of the wires? I was figuring if the song playing had distinct bass notes spaced far enough apart, you could see the rice bounce up on each beat as opposed to the cone sucking down and returning back to center if the the polarity was backwards. Something like the intro of Blue Monday, or something else with the beats spaced further apart.

Anyway, it was just a thought for a visual radio play test. I personally would just battery test the wires from the head unit side and then make sure they’re connect correctly to it, then correct the Metra adapter if needed.

 

I’ve done a really bad job of explaining things, and looking back, I think I’ve been a bit snippy. Guess that’s what I get for replying after a tiring week. Sorry about that. I’m also (clearly) not an audio expert.

Anyway, speakers move both in and out during normal operation. Essentially they’re being fed a sum of sine waves that are more or less centered on zero. The battery test just lets you know relative phasing. So if you hook a speaker up “backwards,” all you’re really doing is changing its output by 180°. If you were running one speaker on a mono system, you could swap the terminals and never know the difference.

Apparently it’s not uncommon to play with speaker phasing in automotive applications, which in hindsight makes sense. I’ve done essentially the same thing with my systems at home in the past. The OEM speaker could be in “backwards” intentionally.

I did also think about the voltage measurement. I think my explanation is probably wrong (or at least partly wrong). I expect that was just a DC offset, but I’m not knowledgeable enough about class AB amps to know if that offset will always be positive in a specific orientation. I’m not convinced it would be.

I still say that the best thing to do is hook it up and listen. If it doesn’t sound right, swap the terminals.

 

Not an audio person, but I remember a video on YouTube describing how to test with one of those square batteries (8v?)

 

I wasn't terribly concerned over it - just curious. I did hook them up using the wiring adapter and they sound great. I never heard the OEM mid range speaker so I have no benchmark for comparison. I have read ( could be B.S.) that is both speakers are wiring the same there should not be an issue. I think deepgrey is on to something - it seem weird. I would recommend the Polk DB652 as a replacement and they are also marine grade for a little water protection. Even though this Mini was garage kept (until recently) and only has 37K on it, I still found water in the door after a rain. The windows rubber seals look new and still extremely flexible. At $88 a piece I think I will pass on new ones for now.