Speaker Wiring/Polarity

I put all new speakers in my truck, and they just didn't quite sound perfect from one side. I figured I'd check the speaker polarity since I got a multimeter for cheap.

I did exactly this:

https://www.youtube.com/watch?v=xoUHbf_bRxw

Just wanted to confirm but it looks like one of my speakers was actually reversed (getting a negative signal when measuring). Whoever wired up the speakers before me, had them switched. I'm going to check all my speakers.

 

Another way is if your on the radio end and can see speaker cone. Is to use a AA battery and hook it up to the speaker leads. The speaker cone will move out when the polarity is correct.

 

I worked in the car audio days for 7 years. I’ve forgotten a lot of it but I do remember that’s how we would check to make sure speakers were in phase. We used a 9v bat. Put the positive lead off the battery on positive speaker wire, same with the negative. If the speaker pushes out then it is correct polarity. If speaker sucks in the polarity is backwards.

 

If they are all reversed it would mean nothing by correcting them.
You could hook all of them up all backwards and 0 difference.

 

This could totally be my near geriatric brain remembering incorrectly, but IIRC, speakers that directly oppose each other, one should actually be reversed.

When the cones face each other, they could actually cancel each other's sound.

I know for sure back in the day I had a 2 speaker bandpass box, and the 2 subs were bolted to a plate face to face, and one speaker was reversed.

 

The speaker itself is not the problem - I can see the "+" and "-" signs on the speaker. The wiring coming from the truck is suspect. I've seen that method of hooking up wiring and looking at the speaker, but was hoping for a more concrete method of determining polarity.

The problem is if one or more of the speakers are out of phase vs the others, will cancel sound.

Also, I'm thinking at because the speaker was moving inward, instead of out, that it was causing the sound waves to bang of the inside of the wall of the truck and sounded like shite.

I was going to make a whole other post to ask about door insulation too, because when I did my speakers, there's none of the plastic on the door and going over bumps or with the music or even just closing the door, there's some slight annoying rattling going on inside. Either from the door handle mechanism, or the lock, or both.

 

You are correct it was a 9volt not a AA. Been along time since I had to use that trick.

In a bass box yes one would be reversed when firing at each other.

 

How do you figure?

 

True, I guess the idea with the subs is that they don't physically hit each other.

I would just hook them up, and if it sounds like shit, reverse it, if it sounds worse, put it back, lol...

@ssoulssurfer, the plastic on doors is a weather guard, not for sound insulation. You want as much insulation as possible. Doors SUCK since you can't really access the inside very easily, but you can usually stuff decent amounts of dynamat in there. Manufacturers put the minimum amount, usually small squares of rubber sheets to give a decent audio sound and that nice "thunk" when the door closes.

 

Made another post to address all this, and great idea!

 

The signal is ac. Only difference wiring backwards makes is the phase. You want all cones pushing out with a positive or even with a negative as in this discussion. Makes no difference. You don't want any mixups/differences in polarity from each other so a speaker is cancelled out by 180 degree phase difference. As long as they are the same polarity hookup, you can even have all negatives on + terminals, it makes no difference.

On the back of subs you have a 180 degree phase switch.
You want sound waves to add not cancel each other. Depending on your seating position a phase difference of 180 might actually sound better in one area than another such as in a sub or dual subs.

 

So just to confirm, is that method solid in determining polarity of the speakers (like in the above video) i.e. check dc voltage of the wires with a multimeter? As it looks, on of my speakers was definitely wrong

 

Since the door speakers face each other they should both go high and low at the same time so there is pressure generated. If one went hi as the other went low there would be cancellation to some degree, and your brain might hurt a tiny bit from the difference.

 

Nope, that video has no relationship to audio. Audio is AC, the power supply is DC. There is no a way, short of using an O scope, to check the phase of an audio signal. Just make sure all your speakers are wired the same. There is no positive or negative with audio. The speaker terminals are marked + and - so you can keep track of phasing. A and B marking would accomplish the same thing.

 

Hmm, really? guess I'll have to check the others, but then could I still use the voltage measurement as a baseline and just see the "+", "-" signal, maybe just measure AC instead, i.e. see if they're all "-" or "+"?

I'd like to avoid having to take out the stereo again, but guess I could do that and just get a 9 volt battery and test the wires from the stereo side and leave them connected to a speaker to test.

 

Nope, the AC is pretty fast, mostly faster then the human eye, like anywhere from 20 Hz to 20,000Hz. There is no way to check the phase with a voltmeter. Don't obsess over this. If it sounds good to you, it sounds good. In theory, all the speakers should be the same phase but you would be hard pressed to hear an out of phase speaker in a truck. The speakers would have to be facing each other with nothing like seats and consoles between them.

 

Ok, well I just ordered some sound skins to deaden the doors and inside where the rear speakers are, I did just want to double check somehow that the speakers were correctly wired because the left rear has sounded a little off.

 

So I'm totally lost but hard to shake the ocd, now I just have no idea if my speakers are wired correctly or not, and no way of double checking?

It seems like sometimes they're moving towards in the inside and banging sound waves off the cab (partly why I think the sound deading stuff will help)