Factory speakers out of phase?

Discussion in 'Gen 3 Prius Audio and Electronics' started by billshadow00, Nov 27, 2010.

  1. lopgok

    lopgok Member

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    The plug in prius of 2012 has 2 stereos available. The base model, and the JBL overpriced silly greenedge system that comes with the 'advanced' option.
    The base model has a slot for the cd and the screen does not move.
     
  2. la-tin phv

    la-tin phv Junior Member

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    OK. That's what I had thought too, but was not sure why you would want to compare that with the Premium HDD. I think the two have way different sound quality, but I have to admit so far in my test drive (before I bought the gen3) I only were listening to the "front" zone, never sat in the back.

    In any case, I know this is not a stereo quality or speaker quality. This is wiring issue or as someone said this earlier might be a "software trick" in the amp itself (though I doubt it).

    I guess so far no one has complained or has talked to the dealer. I will see what they say if I go to the dealer for them to have it checked out. It's still under warranty, so....
     
  3. oldtone

    oldtone Junior Member

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    You might be able to check phasing with the balance control on the unit. I seem to remember that if the speakers were out of phase, you would have more bass when the balance is full to one side. As you adjust the balance back towards center the bass should decrease as it mixes with the other speaker, if it's out of phase.
     
  4. greenJeans7

    greenJeans7 Junior Member

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    I decided to check the phasing after upgrading the front door lower speakers and found out there are IOS and android apps for checking speaker phase.

    But be prepared to go down the rabbit hole....

    After getting unusual results when I check the phase in the upgraded prius, I checked the phasing in another car, a stock gen 3 with the 8 OEM speakers still intact.
    (Both cars are 2013 Gen 3 with JBL premium 8 speaker sound systems.)

    I got some puzzling results.

    The left front two speakers are in phase with the rear right two speakers, same for the right front speakers they are in phase with the rear left speakers, like a "criss cross" phasing arrangement. I've uploaded a image of my results.

    Both cars tested had identical phasing so not a wiring error as the stock car with OEM speakers tested the same as the upgraded one.

    I'm guessing this is intentional, but I know the standard is to have all speakers in phase so one doesn't cancel the other out so I'm curious if this is an valid technique for car audio, or if I'm just getting bad data because of the android apps DSC_3353.JPG .

    Tried both Polarity Checker and AudioTool apps with same results, though AudioTools seems the most stable / repeatable.
     
  5. Grit

    Grit Senior Member

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    Impressive discovery. Now I'm tempted to install my 19" dbx RTA rackmount in the prius and see the frequency curve for it to produce a flat eq response for pink noise.
     
  6. greenJeans7

    greenJeans7 Junior Member

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    Now I may try that myself as audiotool has a pink noise generator.

    Someone else mentioned that the factory amp uses DSP to alter the ambience of the sound, so that may be the reason for the unusual phasing.

    I also noticed the factory speakers have "acoustic lenses" which JBL state is intended to improve the sound coverage for all occupants as well. Guess it makes sense, because if you adjust the balance for the driver, for example, then the other occupants would have subpar sound.

    The aftermarket speakers did improve the sound quality significantly, and the rear seats got a volume boost as well, oddy enough.

    According to Crutchfield install info, it's important to use low impedance speakers as the amp requires them, which I did and didn't suffer any volume loss and actually gained some volume in the rear speakers. The speakers I installed were rated at 2.3 ohms.

    Probably will replace the rear speakers as well and not worry about the phasing as it sounds fine as it.
    Plus an auto interior is at best a compromise when it comes to acoustics.
     
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