Hey guys, going thru a little speaker fiasco here and pretty much need to know what wires ar + and - for rear doors... depending on the source the polarity changes, which leads me to believe lots of people have reverse wired speakers...

Best buy says in the right rear door Brown with pink is hot and orange and red is ground, where ABC warehouse says the opposite... and when it comes to google I find that some sites say orange and red is + and brown with pink is - and other sites say the opposite.

I cant find my manual, does anyone know what colors are + in the rear supercab doors? I'm ready to solder them in but dont know which is positive...

 

Speakers push outward when a positive voltage is applied. If the speakers aren't marked, then apply voltage with a 1.5 volt battery. The cone should move out. The same applies to the music. If the cone drives out on a big note, then it's correct. If it tries to pull in, then it's incorrect. Hope that helps.

 

That helped, had to use a white crayon to mark it and tell which way was outward but this worked... turns out my truck dont have any of the right colored wires in it anyhow so it took me a few tries but I got it.

What I dont understand is why the fluke couldnt see a voltage between the stereo + and -... both wires read +6 volts when grounded out to the door hinges and that really threw me for a loop. Setting that aside, the speakers work and i believe in the correct fashion. If they are indeed backwards I'll correct them when i get my replacement door panels... needless to say I dont think they were designed to come off in 32 degree weather.

 

Because that's not how an amplified signal to a speaker works.

You're not reading standard DC voltage. I'd be willing to bet money that you had your meter on DC Voltage.

Check it out:
YouTube - HP 8064A Real-Time Audio Spectrum Analyzer

What you were reading was basically a RMS voltage of the 20Hz - 20KHz freq spectrum that was being sent to your speakers at whatever volume level you were at. The reason you could measure from either + or - is because you were measuring an amplified audio signal in compared to a 0V reference or ground.

In the above video you can see the low frequencies on the left and higher freqs on the right. Up and down on that display shows output level at those specific freqs - for a brief moment.


If you turn the volume up the outputs will all increase, but they will stay the same relative to one another.

So, as you change your volume and have your meter connected, you'll see that 6V reading on your meter will coincide with your changes to volume. The reason for this is that the - wire isn't ground it's simply - (negative) in reference to the phase relationship of the audio signal and the speaker. Connecting - to - and + to + puts the signal and speaker "in phase".

This is also the reason you're getting voltage on BOTH + and - speaker wires in reference to vehicle ground which is neutral. - on your speaker is not neutral or ground. Notice you don't connect it to all of that surrounding sheetmetal?

To get a more accurate idea of what your speaker "sees" as music is played, watch this video: YouTube - oScope for iPhone, a sneak preview #2

Pay attention to the waveform of the green scope when the music plays. Notice that the signal is moving up and down from center. That center is actually 0 volts (unless an offset is put in but that's beyond what we're talking about).

Now, for your speaker, everything on the top side of that 0 line, or scope trace, will go to your + connection on the speaker. Everything below that center line is - and will go to the - speaker connection. Unless there is a DC offset the + and - signals should be (roughly) equal. These + and - signals pass through the coil of your speaker and create a magnetic field. That magnetic field generated around that coil will make it move in relation to the magnetic field of the fixed magnet of your speaker and you get sound.

When you wire the speaker backwards, - to +, you have connected the speaker "out of phase" (180 degrees out of phase) which, in most instances, is not what you want to do.

Now, if I haven't completely lost you yet and you're curious about DC offset...

Remember I mentioned DC offset and that 0 line in the center? If you have the right equipment you can dial in a DC offset that is either + or -. Doing this will basically limit travel of the speaker in one direction. Let's say you dial in a +1V DC offset. Knowing that applying + to + and - to - at the speaker will make the cone travel forward (or out) you can make the assumption that when you dial in a +1V DC offset the speaker is starting with the cone moved forward a bit and will play from there with the incoming audio signal. What this +1V offset has done is that is has removed a bit of excursion, or travel, from the speaker in the forward direction.

 

Good info JIA!