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Cone has a small dent/scratch. Audible?

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  • Cone has a small dent/scratch. Audible?

    I was in the process of redoing my boxes. And i noticed about 3 of my mids, have very small dents/scratches. Pictures below can be seen.

    I was just wondering if this will be audible?

    And how can I test the impact of them to see if they are still working as intended to?

    I was thinking of measuring all the mids against the one that I know is in perfect form. Should I do it 1" away like with subwoofers? Or should I do it 1 meter?
    Attached Files

  • #2
    I suspect the dents may technically cause a miniscule change in frequency response from undented, but only by comparing the frequency response graphs previous to the dent.

    If you wanted to test the three dinged units against the one pristine unit, that would tell all. As far as how far to place the mic, I'd do something in between... not so close that it may not pick up the nuances of the outer cone, but not too far away either. Maybe 12-16" or so? Just guessing and trying to apply a little logic to the situation.

    I doubt it will be a true problem sonically speaking. They're nice looking drivers by the way, the cones are spiffy! I know how bad pics can show up dust and stuff, but I bet they're cool looking speakers.

    TomZ
    *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
    *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

    *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

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    • #3
      "Will it affect the sound?"

      Only if you can see it.

      Sorry, couldn't help myself.
      Probably no effect unless you've crossed in the breakup region, then only at very high levels, and not audible because way less than production variances.

      If you are determined to detect such, look at distortion profiles

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      • #4
        It may improve the sound.

        Comment


        • #5
          Originally posted by djg View Post
          It may improve the sound.
          I was gonna say that too. In all reality ignore it entirely. There is the slightest possibility it could lower the Q of the cone resonance. With that it may widen the range of breakup but with less amplitude.

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          • #6
            Okay. So I couldn't get over them!


            I measured ALL six of my Zaph ZA5 mids. And I am so glad I did.

            Firstly, all of the measurements were done in the same exact conditions. I had it in my enclosure, with one of the mids and tweeter removed from it, so there were 2 big holes. And I wired it to the upper mid on the crossover. Not sure if I got the polarity right as it was supposed to be on the crossover, but I did use the same polarity throughout this test. 10" away, pointed right at the mid.

            So basically. You were all right. There was no impact that I could find from the small dent/line/dinged unit based on measurements.


            Here is what happened though.

            I took my FIRST mid, which was totally okay. Measured it. Got a response.
            Took my SECOND mid, which was also totally okay. Got a response, with a 5db dip.
            Not knowing which one is correct, I kept going through all of them.

            The one with the scratch/dent and all others matched my FIRST measurement.
            Now this is totally bothering me. The mid that shows no physical damage or anything upon inspection, shows a 5db drop around 1500hz and has higher distortion too.

            Graphs are here.

            Comaprison of all the mids FR

            Click image for larger version

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            This is the distortion for my first mid/woofer which shows no dip.


            Click image for larger version

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            This shows my second mid that I checked with no physical damage.

            Click image for larger version

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            • #7
              Could this be something on my end? Or is it possible that its a production error?

              Before anyone says might be a measurement error, I measured it 2-3 times to be sure, and had very similar dips.

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              • #8
                Try rotating the driver 90 degrees.
                Also, when checking again, are you setting it up from scratch or pushing a button and running it?

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                • #9
                  Pushing a button and running it basically.

                  in the tests you see above.

                  but after that. I tried all over again with this faulty driver and another driver. Same thing. This showed this same 5dp drop.

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                  • #10
                    My guess is some manufacturing "flaw".

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                    • #11
                      Click image for larger version

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                      Some people pay extra for those
                      Copy of Lou C's speaker pages: http://www.rob-elder.com/LouC/speakers.html

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                      • #12
                        This is the ONLY thing I could find that was visually different from the other drivers that I have. Some of the other drivers have this too, but not as prominent as this. What is this exactly? Is this normal?





                        Click image for larger version

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                        • #13
                          Looks like epoxy holding the rear plate on . . .

                          take a look inside the rear vent hole w/a strong light and make sure it's not obstructed by a glue glop on one.

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                          • #14
                            Originally posted by Chris Roemer View Post
                            Looks like epoxy holding the rear plate on . . .

                            take a look inside the rear vent hole w/a strong light and make sure it's not obstructed by a glue glop on one.
                            Done. No obstructions there!

                            I am guessing its a production error.

                            http://www.zaphaudio.com/ZA5/

                            I have the choice of using this in the Zaph 5.3T(2.5 way), or the Zaph 5.3C (center).

                            I was wondering how to get the most out of this driver without it affecting the sound? I could put it in the center because I don't watch too much movies anyway. So I'd barely have to go through whatever little impact this has anyway.

                            Second thing I was thinking is, I could use this as the BOTTOM part of the TMM. Which will only be in the bass region, and I believe this goes to 300hz I THINK, if I am studying the graphs right on the the link I posted above. Because till 300hz the measurements don't seem to that off anyway.

                            What do you guys suggest?

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                            • #15
                              The TMM bottom is about 8db-10db down by the 1500hz-1800hz problem areas if I'm reading things right. I don't believe the problem spot is big enough to make a very noticeable difference since it appears to be about 2db-3db and placing it 8-10db down should help. I think folks who are crazy-good at recognizing little things like this will still be able to hear a difference though and it might affect your center imaging for music with the Left/Right speakers not being as perfectly paired/symetrical as possible.

                              http://www.zaphaudio.com/ZA5/ZA5.3t-FR-individual.gifClick image for larger version

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                              My first 2way build

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