car stereo speaker polarity?

[chet]

hey guys

putting my bro's speakers in his new (well, new to him) car. We've taken out the old speakers, and now can't tell which wire is + and which is - . Neither has a stripe; one is grey and the other is blue.

Do you know any way of testing this?

Don't really feel like ripping out the head unit to trace the wires back.

[5lab]

shouldnt matter to be honest.. occasionally you will get a 'buzzing' noise if you wire it the wrong way round, but i just plug mine in any-old-how

[Howard]

It will matter cos it'll be out of phase and sound awful.

Are the leads grey and blue at the head unit end, and does the head unit have positive and negative indicators?

If you have a multimeter you could find it using that. Also, the old speakers, did you just cut the wires or de-solder them?

Or if you're not so fussed wire them both up the same way round (blue to positive on both speakers, etc). It'll be out of phase but it'll sound better than having one out of phase and the other in phase I accidentally did that when I was wiring up some speakers in my car yesterday... Turned them on and thought "What the crap... Where's all the bass gone?"

[Kumagoro]

like howard says it does matter and can damage them.

[Angus]

Surely you don't need to rip the wiring out..

Just slip the headunit out and have a look where the wires go in.

[Zak33]

thread moved to Cars n Bikes...

I bet one cable has a rough edge to it...all along itas length...like a ridge

[Rave]

It won't damage the speakers or cause a buzzing noise or anything like that- at least there's no scientific reason why it would. If you wire both speakers the same way they may or may not be 'right' but I'm pretty sure they'll sound fine either way. You'll only have problems if you wire one speaker out of phase with the other like Howard said.

[Jiff Lemon]

What model car is it?

[5lab]

It won't damage the speakers or cause a buzzing noise or anything like that- at least there's no scientific reason why it would. If you wire both speakers the same way they may or may not be 'right' but I'm pretty sure they'll sound fine either way. You'll only have problems if you wire one speaker out of phase with the other like Howard said.

the buzzing theory came from the manual for my home stereo - it said that if you can hear buzzing try swapping the polarity round - might be something to do with the ac source?

[Rave]

the buzzing theory came from the manual for my home stereo - it said that if you can hear buzzing try swapping the polarity round - might be something to do with the ac source?

Hmm.....I can't see why that would make any difference. Car stereos obviously aren't prone to 50Hz mains hum, but there's plenty of other radio/electrical noise in cars I think. I suppose swapping polarity if you get noise is worth a try, no harm done if it doesn't work.

[Konan555]

Just get them the both the same way around and you'll be OK.

[Russ]

if you tell us what car it is we can help

[Kumagoro]

As far as i remember speaker throw is not even so if you drive a speaker with an inverted polarity you can damage the speaker if you have it up extremely loud over a period of time.. So i wouldnt worry about damaging it while testing it. If you need to test the speaker polarity then use a battery (bypassing the crossovers) if it pops out then thats positive etc dont have it connected for long though.

[unrealrocks]

Inverting the polarity simply messes with the phasing, it doesn't damage the speaker in the slightest (its just a myth) as all your doing it reversing the phase of that speaker by 180° (like on expensive studio monitors you can do that with a switch ). So long as you keep all the speakers in the same phase (all speakers with the wires the same way round) it shouldn't matter although it is better to have them the right way round (but most commercial music has no DC offset so it isn't too bad).

[5lab]

yeah its important to remember that a typical sound wave will have exactly the same max+ve voltage as max -ve voltage, and on average there is the same amount of +ve as -ve total power sent - so even if a speaker has more throw in one direction, it will work just as well plugged in either way

[chet]

it's a 94 Honda Accord.

But I don't think this will help, as who knows how the blue/grey wires have been connected to the HU...