Hi,

i'm in the midst of doing my rear speakers. Which color is + and which is -. Blue or Red? Thanks a lot.

-jeffrey

 

usually red is +

 

It would help if you told us which car and what year you have.

 

2004 wrx wagon. Thanks.

-jeffrey

 

It really doesn't matter. As long as you install them in phase with the other speakers. For RR adjust your balance to the right and place it on a radion station that is all white noise. You'll be able to tell right away if it is right or not. If it is out of phase it will sound detached or sound emmiting from somewhere else. In phase it will sound the same. You should always to a phase check when doing a stereo/speaker install. Things get mixed up.

 

wow. thanks a lot. I'll try that right now.

-jeffrey

 

"it doesn't really matter?" I would have to strongly disagree with a claim like that- it matters quite a lot, like you say- "as long as they are in phase with the other speakers"

But if they are not, not everyone can tell, but if you sweep the fader from front to rear and the sound image seems to get thin in the middle you probably have them wrong.

and +/- isn't "phase" its "polarity"

 

Nope sorry. The speaker doesn't care about polarity nor does it care about phase. The only thing that will be affected is the efficency of the speaker in the sound system. To say that the stock wiring is still the same polarity after changing the system is a little presumptuous. That's why I believe that phase is more critical than polarity at this point.

 

i think it's quite possible that the audio shop that did the components in the front screwed up.

Does the thinning from left to right apply too?

 

Absolutly. The whole idea of phasing speakers in about efficency. You want to be sure that all of your speakers are pushing and pulling at the same time. Otherwise the speakers that are out of phase negate one another. Audio calibration CD's are available almost everywhere. Most of them have a phase testing track. WHen I do it I do Front, Left, Right, Rear. It is very hard to set up polarity with all four speakers on at the same time. To change phase you simply swith polarity on one speaker.

 

Nope, sorry?

Do you have a degree in Electrical engineering?

Have you been designing and building professional sound systems for the last 20 years?

Do you have any patents pertaining to phase correction circuitry in loudspeakers?



I never said the speaker cares, and it isn't the efficiency as much as the system response that is effected by incorrect polarity.

Phase is the relationship between waveform peaks at a given frequency, phase can vary from 0 to 360 degrees, and phase is very difficult to measure without sophisticated instrumentation.

What you have been mistakenly calling phase is in fact polarity.

Apart from that your advise is sound, but try not to second guess people who might know more than you do about something...

Perhaps you could learn a thing or two from this:

http://www.prosoundweb.com/studyhall..._and_phase.pdf

 

EDIT: I misunderstood the question, please ignore my post.

 

Did question your credentials? Your simply stating exactly what I am stating with different verbage. In this case there is a direct relation between polarity and phase. Especially now that he is questioning the proper polarity to begin with. If his polarity is correct throughout the entire system, chances are more likely than not, his entire system will be in phase. When there is a change polarity say by improper connection, unless the other channel was connected improperly, that particular set of channels will be out of phase from it's original intention. Polarity is easily identified if a direct connection is being made from source to speaker. When making a more complicated connection through multiple components, existing wiring, crossovers, ect you chances of reversing polarity greatly increase which in turn will also reverse your phase. Therefore effecting the speaker efficiency within the system.

 

Ok I see what our saying. I stand corrected. Although the method is correct.

 

Actually - polarity and phase are two different things.

Polarity has to do with the connection on the speaker. if connected corectly the speaker should move outward during the positive wave of the signal.

Phase has to do with the relationship between the speakers in the system.

Efficiency has absolutely nothing to do with this. Efficiency has to do with the speaker's ability to transform electrical energy to audio waves. If the system is efficient then it will take very little power to have a lot of sound.

If you connect one speaker polarity opposite of the other channel you will get frequency cancellation, typically in the mid-bass and lower frequencies. If you are not using a subwoofer it is even more noticeable.

Using a dead radio station to determine if a speaker is out-of-phase does not work. Actually I have never even heard of this before.
A simple test would be to use "pink noise" (from any one of a 1000 test disks available) while listening to the right and left speakers together (start with the front, then the rear and then combine them all).
If the speakers are out of phase the "pink noise" will seem to come from the sides of the vehicle (low in the doors). If the speakers are in-phase the noise will seem to come from the general center of the vehicle.

If you use phase test tracks these require and expensive phase tester, if you use your ears with a single speaker you can not hear a difference, because people do not hear changes in phase. But you can hear the difference in the frequency response that comes from combining two or more speakers. If the speakers are out of phase then you will notice if big difference in mid-bass, test this by using the balance between the right and left speakers. Right has bass, left has bass, but together there is no bass = out-of-phase.

As for the change in phase through various devices, such as crossovers, this is only a factor if the signal for one side goes through different networks then the other side. If the components are all the same then the signals are affected the same and it can not be heard.

According to Subaru wiring diagrams the correct connections for the rear speakers are:
Red / White strip (+)
Blue / Yellow (-)
Same for both sides

The front speakers are:
Green (+) right side
Brown / white (-) right side

White / black (+) left side
Red / yellow (-) left side

And for those who care:
I am an electrical engineer that works for a leading loudspeaker company and I have specialized in mobile audio systems for about 10 years.