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Speaker Phasing in regards to TA and SQ

Discussion in 'Audio & Video' started by brian, Oct 26, 2012.

  1. Oct 26, 2012 at 6:55 PM
    #1
    brian

    brian [OP] Another Traitor

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    Someone really needs to clarify speaker phasing to me. The way I always understood it, was used for those who either run their woofers inversely mounted, or for those who wired their shit backwards. The intent was to make the speaker fire in the correct direction.

    In the pioneer manual, I remember it specifically said something to the extent of playing with the phasing to affect sound quality.

    I realized I could do it on my tweeters tonight and all I gotta say is holy shit. I know my stuff isn't wired backwards so I'm confused on the huge difference, especially on a free air speaker such as my tweets.


    Someone an expert in this?
     
  2. Oct 27, 2012 at 12:58 PM
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    shaneckc

    shaneckc Fyntünd Designs

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    Quantify. What was the phase shift that you applied to your tweeters? Explain the change in terms of your sound that occurred when you applied the phase change.

    The way I understand phase shifts from trigonometry in terms of sine waves makes the most sense for time alignment, but I'm not 100% sure.

    This is the graph of a sine wave:
    [​IMG]

    This is the graph of a sine wave with a 90 degree phase shift:
    [​IMG]

    I put the units in terms of radians because that is what I'm used to.

    So shifting the phase would alter the time at which the signal is played by the driver which would set a delay, which is basically what time alignment is.

    There might be more to phasing than this but this is all that I'm familiar with at this point.
     
  3. Oct 27, 2012 at 11:25 PM
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    brian

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    Yes, what you're stating makes sense... but I'm talking about a 180* phase shift, which is a feature in head units. I think I somewhat figured it out though.


    If you can read this: I guess it makes sense.

    [​IMG]
     
  4. Oct 28, 2012 at 1:20 AM
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    shaneckc

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    Yeah, I probably should have included the graph for a 180 degree shift hahah.
     
  5. Oct 28, 2012 at 6:42 PM
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    brian

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    I think its starting to make even more sense because I have both my sub and my tweeters reversed now.... midrange in norm. It just sounds cleaner.
     
  6. Oct 29, 2012 at 1:24 AM
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    shaneckc

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    If I remember correctly, your crossover points between your tweeters and mids are pretty far apart, so inverting the phase on either of them shouldn't result in any cancellation. That being said, the only thing I can think of that would explain the difference in sound quality that you've found is the potential delay caused by inverting the phase on your tweeters and subs. I've never thought of inverting the phase on speakers to emulate time alignment before. When I'm at my shop on Tuesday, I'll see what my boss has to say about this. He's a real expert.
     
  7. Oct 29, 2012 at 6:27 AM
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    brian

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    The crossovers match up to the same point though. No gap in sound. I've heard of reversing wires to do a 180 phase shift for TA back in the day but never understood it until now
     
  8. Oct 29, 2012 at 8:38 AM
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    ItalynStylion

    ItalynStylion Sounds Gooooood

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    Changing the phase is critical to getting proper sound in a vehicle. I always wire things up with correct polarity and then change things on the headunit or processor. You will likely hear the MOST difference by changing the phase on your midbass drivers by doing it one at a time. The phase on the tweeters will sometimes help center the image and raise it up.


    The idea that you want the frequencies to "mesh" well and be in phase is correct. The way you're thinking about it is that the listening point is equidistant from both sources (speakers). The reality of the situation is that the speakers aren't even close to being the same distance since you sit on the left side of the truck. Case in point, take the graphs that Shane posted and shift the one on the bottom right just a little. All of a sudden the graphs are in phase. With a path length discrepancy the perceived phase of the output at a certain point in the vehicle can differ significantly.
     
  9. Oct 29, 2012 at 4:17 PM
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    brian

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    I was hoping you could give some input eventually :) I originally had sub rev, mids norm, and tweets rev. I swapped the mids to rev now, and tweets to norm. It sounds different, I'm unsure if I like it, but I'll give it a shot for a day or so. To me it sounds like the mid's aren't putting out the full sound that I was used to. I think its cancelling out somewhere. I think I need to find out if I can reverse the signal per speaker and not per channel. It 'appears' that I can, I just haven't figured it out yet. It displays "REV/REV" in the display, but they both change when I hit the button. Nothing in the manual about individual setting. Gonna tink with it. I'll figure it out. I'm glad the radio holds the settings when you disc the battery... LoL
     
  10. Oct 29, 2012 at 5:32 PM
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    ItalynStylion

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    Definitely experiment with throwing a single mid out of phase. I think my setup likes the left mid out of phase but the right one IN phase. I'd have to check to confirm that.

    Things will really start getting dialed in when you treat each speaker as an independent unit. Remember, in car audio, unless you drive a Mclaren F1, there is NO symmetry. So you need to tune each driver on it's own. Your whole left side should be about 1-2db lower than your right since you're almost twice as far from it!

    Lotta tricks to learn but you'll figure it out man.
     
  11. Oct 29, 2012 at 7:24 PM
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    brian

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    Yeah I finally figured out how to do each one. Menu system in this head unit is the worst I've ever seen...lol

    So when I throw them out of phase I'm probably gonna have to retune the TA again. I can't find that happy spot any more.
     
  12. Oct 29, 2012 at 8:00 PM
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    ItalynStylion

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    Bingo.....it's all about the balancing act. You'll have to retune again and again. The good news is it will continue to get better!
     
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