I noticed today that there may be an issue with my ML system. You too may have the same issue. I have never been thrilled with the sound of the stereo in my car and started to investigate today. Supposedly, it's supposed to be "sooo good" etc, etc, but I always found it to be merely adequate. I had a loaner IS250 this past week without premium sound it it sounded better than my LS.

What are my complaints? Well, no matter what position the DSP is set to, I don't get a solid center image. A telltale sign of a polarity issue.

Couple of things I noticed. It appears the front woofers are wired out of phase. I verified this with a simple test from http://www.audiocheck.net/audiotests_polaritycheck.php and can be played straight from your iphone via the tape deck. Its very easy to hear the differences of in and out of phase.

Listen to the guitar, if the system is wired correctly, you will hear the guitar more focused etc. Mine sounded more focused when i played the out of phase file. FML. I also checked the rear speakers,(which were wired correctly via the test) and while I was in the back seat, i noticed that the treble response was MUCH better, almost making the front stage seem dead and lifeless. It made me think that both my front tweets were shot and only the midranges in the dash were playing. Hmmmm.

Now, your mission should you choose to accept.......

Run the same test I did.

Listen to the files- when you hit the in phase file it should sound more precise and come from the center, if it sounds more focused with the out of phase file, then your fronts are wired out of phase, like mine. Also remember to use the fader to only have the fronts or rears on when working with the respective speakers.

Don't forget to let me know if your front treble response is poor compared to the rear. It is very noticable in my car.

Let me know what you think!

 

do you guys think it's possible that the speakers being out of phase vs. the rear speakers is done on purpose to give a more broad image? I'm reading in other forums that some cars do this on purpose....

 

Can anybody maybe at least try listening to the rear speakers vs. the front speakers and tell me if their front speakers sound considerably less crisp than their rear speakers?

 

I don't have an ML system so I can't speak to the differences in high frequency output between front and back speakers. The fronts have separate dash mounted tweeters so the drivers in the doors will not be getting the HF being sent to the dash.

I can say that based on my experience Toyota makes and utilizes rigid plastic connectors for its speakers, and like most plastic mounted electrical connectors can only be attached one way - therefore if an OEM speaker in a Toyota product appears to be wired out of phase, it was certainly not done by mistake or unintentionally by the manufacturer.