Need Quick Help--Car Speaker Polarity Test

[cgarges]

Hey folks,

I just had some work done to my car and I have this suspicion that the guys at the dealership wired my driver's side door speaker out of phase when they put it back together. It's kind of hard to tell (since it's a car), but I'm fairly certain that that's what they did and I want to make sure it's correct. Does anyone have a car speaker polarity test of some sort they can email me or point me towards so that I can check this out ASAP? These fucktards at the dealership have been totally troublesome for me, so I'd like to remedy this situation as soon as possible and just get it done with. Any help would be appreciated.

Chris Garges
Charlotte, NC

[shedshrine]

Short of pulling out speakers and a/b ing (unmarked?) speaker terminals, maybe run a cd recording of something that is in then out of phase?

Better yet, listen to Shiny box!

[ulriggribbons]

Sure,

normally, the speakers polarity is marked on the back, look for a + label on the tag strip.

If it's unmarked, you can use a 1.5V battery. connect one end to each terminal. If the speaker excursion moves out, then it's polarity is correct.

Or are you looking for an audio test to help determine this?

hope this helps

ju

[cgarges]

Well, the thing is, the inside door panel needs to come off to get to the speaker. This car has an extensive warranty, so if they did indeed wire it backwards, they should fix their fuck up.

I've got a plan to test it with a polarity checking setup on Thursday, but didn't know if anyone might know of some kind of car stereo calibration audio or something I could get to sooner. I just want to be sure before I go back to them with this weird request. If there were a way to sum all the speakers, I'd know for sure. I guess I could listen to some mono recording and sit right in the middle of the car, but I'm just looking for a more scientific approach so that the guys at the dealership don't think I'm crazier than they already do.

Chris Garges
Charlotte, NC

[xonlocust]

hey chris-

dunno if this is of any use:

http://posthoneymoon.com/polaritytest.mp3

i just recorded the output of my minirator on the 'polarity test' function into PT and made a quick mp3. it'd probably be a lot easier to tell if the two speakers were side by side, then you could see if they are moving in the same direction.

there's also the virtual minirator these days here:

http://www.nti-audio.com/Home/Products/ ... fault.aspx

nk

[Snarl 12/8]

I dunno Chris. If you've got some sort of simple, mono, waveform type CD you can play, you should just stick your head in the middle of the car and test it. If you can convince yourself that it's out of phase, then you should probably just pull the "I'm an engineer" card and convince the dealer people.

Can you get to the amp more easily? It might be in the trunk, under a seat, up under the dash. It might be easier to flip the offending wires there.

[xonlocust]

i also am having a great time envisioning the conversation you're going to have with the car dealer about this..

chris: the speaker is out of phase?
dealer: blank look.....
chris: like, the sound out of this side is opposite of what's coming out on this side..
dealer: but sound comes out of both of them just fine, what's the problem?
chris: i'm an ENGINEER!
dealer: blank look.....

[Snarl 12/8]

My daughter had tachycardia a while back. I called the advice nurse and told her that it was somewhere north of 120 bpm. I told her I was a drummer and that was the standard disco tempo back in the 70's, so I knew it well. She took my word for it. It's probably the only time I've ever gotten any respect as a drummer.

[drumsound]

Chris,

Can't you just play the mono special Edition of Village Green Preservation Society with the stereo's speaker fader set for just the fronts?

[cgarges]

It's funny. That CD (the stereo version) is in the other car right now. I don't actually have the mono version. I guess I could use Piper At The Gates Of Dawn. That's a good one.

Thanks for the links, Nick. I need to buy a Minilyzer. We have a Minirator at the studio and it's a terrific piece of gear. I'll actually have access to both on Thursday when I'll do an accurate test.

At this point, I'm kind of embarrassed about being so picky with the dealer, but at the same time, I'm going to kind of enjoy busting them on one of the few things that I'll be able to out-talk them on when it comes to car repair. Dealing with them has been the biggest fucking hassle. On the one hand, I just don't want to deal with it again, but the car does have to go back in anyway for some other stuff, so while I'm there, I'll take a little pride in being able to call them on this, too. It's the kind of simple mistake that anyone who either doesn't know or doesn't care about could do, but they just happened to wind up with the wrong guy to do it to.

Chris Garges
Charlotte, NC

[ckeene]

Can you play a tone, mic all your speakers and see how the waves line up in PT?

[Snarl 12/8]

OK. I've been thinking about this all night. I saw a video a while back about some guy's audio truck. He's the sound engineer for Nascar or something. He pointed to this gizmo up by the ceiling of his control room and said something like "That's my phase indicator (tester?), it's the most important piece of gear in here." This is after showing his wall of amps, his gajillion input SSL desk, his custom monitors, his assistant, blahdittyblah, blah.

I think I've heard of those before. Is that a real thing? Why doesn't everyone have one? What does it do? Could it help Chris here?

[jv]

Can you play a tone, mic all your speakers and see how the waves line up in PT?

I would do this.

[Snarl 12/8]

Can you play a tone, mic all your speakers and see how the waves line up in PT?

I would do this.

And bring in the screen shot of the zoomed in wave forms.

Jesus.

When I was in college I knew a guy who was certified to measure the pollution that was coming out of smokestacks visually. He could write up EPA violations based on that.

Cops can receive training that lets them gauge speeds by eye, and their testimony stands up in court (although a radar gun is even better proof).

I'm just saying, Chris' ears aughtta be good enough without spending hours to "prove" his case. For the techs, just cracking open the door and switching the wires will take 5 minutes. It would take longer to set up the mics and arm the tracks in protools. Even assuming he's got a panel of xlr jacks in his garage.

[ckeene]

Can you play a tone, mic all your speakers and see how the waves line up in PT?

I would do this.

And bring in the screen shot of the zoomed in wave forms.

Jesus.

When I was in college I knew a guy who was certified to measure the pollution that was coming out of smokestacks visually. He could write up EPA violations based on that.

Cops can receive training that lets them gauge speeds by eye, and their testimony stands up in court (although a radar gun is even better proof).

I'm just saying, Chris' ears aughtta be good enough without spending hours to "prove" his case. For the techs, just cracking open the door and switching the wires will take 5 minutes. It would take longer to set up the mics and arm the tracks in protools. Even assuming he's got a panel of xlr jacks in his garage.

I hope Chris does this, and takes pictures. Also, what do you suppose the best mic is for recording test tones coming out of car speakers?