Measuring XMAX without special equipment?

Discussion in 'Home Theater Projects' started by Darren_T, Jul 27, 2004.

  1. Darren_T

    Darren_T Second Unit

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    I'm trying to measure the XMAX that I'm getting out of my AV15... is there a safe way to measure this without special equipment? I'm trying to determine if I'm seeing the full potential of the driver or if it is bottoming too soon.

    I found a way to measure + XMAX but the driver never tries to go beyond half of it's potential even when I push it. I'm trying to see if the - XMAX is different.
     
  2. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    You can calculate the excursion given a certain amount of power using WinISD Pro or Unibox. As for a real world test I'm not sure.
     
  3. Darren_T

    Darren_T Second Unit

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    Yeah, I'm trying to measure realized XMAX...not potential as I am trying to verify my driver isn't suffering from a flaw in the early AV15 design.
     
  4. ThomasW

    ThomasW Cinematographer

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    I thought we covered this in an email?

    It's dfficult to actually measure linear Xmax (meaning the VC remains in the gap) when there isn't proper test gear available.

    With a battery test you can measure Xmech. And that's about as good as it gets without appropriate test gear.
     
  5. Darren_T

    Darren_T Second Unit

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    Hi ThomasW,

    I never got a reply from you... must have been lost in space [​IMG]

    EDIT: I just checked my listed email on the forum and it's an old one. I changed it to my current email. Would it be possible for you to resend the email? I'd love some details on the battery test as that should get me the info I want. Are you talking about the 9v battery test?
     
  6. ThomasW

    ThomasW Cinematographer

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    Darren

    I sent you 3 replies. 2 came back as invalid addresses. So I sent a 3rd via the email system here on HTF.

    Anyway....here's the substance of the email

    One can't measure Xmax without test gear. But one can measure Xmech

    Get little 9 volt battery. Hook it up to the driver with one polarity and the cone will go in all the way. Reverse the polarity and the cone will go out. Note this will only measure Xmech.

    The nice thing about using a battery is that the cone stays in place making measurements easy.

    Don't worry, a little 9 volt is safe and won't harm the driver
     
  7. Dennis XYZ

    Dennis XYZ Stunt Coordinator

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    It won't tell you anything about asymmetry but you can make a wedge micrometer from a piece of stiff paper, as shown on Siegfried Linkwitz's page. It will measure peak-peak excursion while playing a test tone. You'll probably need a bigger one than the pic for the Stryke driver. Play a tone and turn up the volume until you start to hear distortion. Then look at the wedge to see the excursion.

    http://www.woodartistry.com/linkwitzlab/faq.htm#Q29

    [​IMG]
     
  8. Darren_T

    Darren_T Second Unit

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    Thanks ThomasW... it appears all my info was out of date so I updated it. My fault. Thanks for the down and dirty of it.

    Thanks for the alternative method Dennis, I'll try that also.
     
  9. Adam Demuth

    Adam Demuth Agent

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    Awesome... that's terribly clever. Gonna go try that out just for the heck of it [​IMG]
     

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