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What type of failure is this?

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  • What type of failure is this?

    I understand that it's a mechanical failure as opposed to burning the coil but what what specifically? Coming out of the gap? Hitting the magnet? Debris in the gap? Sent from my HTC 2PST2 using Tapatalk

  • #2
    Looks like the coil was driven out of the gap and hit one side of the gap on its return. Did the surround or spider fail as well?
    Brian Steele
    www.diysubwoofers.org

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    • #3
      Surround and spider looked fine with no issues Sent from my HTC 2PST2 using Tapatalk

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      • #4
        Voice coil left the gap possibly? Still seems odd, the level of damage. I've had many coils leave the gap and get jammed or dinged but this is tweaked.

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        • #5
          Over excursion. Whether it hit the back plate or came out of the gap is moot, either way the result is a dead driver.
          www.billfitzmaurice.com
          www.billfitzmaurice.info/forum

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          • #6
            Yeah. short DC pulse at 40V would do that to most drivers- launch it forward and when the DC lets off the overstretched suspension slams the former back into the top plate or back plate.

            Either an amp malfunction (DC) or WAYYYYYYYY too much power would be my guess. Very high power at LF below box tuning could do it too. If you're using vented systems at high power, a high pass filter (in DSP/Preprocessing) is recommended below tuning.

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            • #7
              That speaker was done the instant you heard it go clank!
              Unless you modify your set up and operation it will happen again.

              What model speaker is/was that, the voice coil former looks like an older JBL and what type of cabinet
              was it in.

              Mike Caldwell
              http://www.mikecaldwellaudioproductions.com

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              • #8
                It's an Eminence Difinimax 4012HO. It's my buddy's speaker and it was in a home built folded horn box he bought from his buddy. The driver in the box fires perpendicular to the front of the box - I thought that was kind of strange but I'm super new to this so I'm not sure if that's ok or not.

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                • #9
                  Originally posted by hardcorecap View Post
                  It's an Eminence Difinimax 4012HO. It's my buddy's speaker and it was in a home built folded horn box he bought from his buddy. The driver in the box fires perpendicular to the front of the box - I thought that was kind of strange but I'm super new to this so I'm not sure if that's ok or not.
                  ​Sounds like some sort of tapped-horn design. It's a pretty good alignment, once designed and built properly. Do you have a picture of the box?

                  Brian Steele
                  www.diysubwoofers.org

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                  • #10
                    Drivers in folded horns are particularly vulnerable to mechanical damage as they filter out the high level harmonic distortion that warns of over-excursion in direct radiators. For that reason it's critical that the amp be limited to a maximum voltage output that will prevent over-excursion.
                    www.billfitzmaurice.com
                    www.billfitzmaurice.info/forum

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                    • #11
                      Originally posted by billfitzmaurice View Post
                      Drivers in folded horns are particularly vulnerable to mechanical damage as they filter out the high level harmonic distortion that warns of over-excursion in direct radiators. For that reason it's critical that the amp be limited to a maximum voltage output that will prevent over-excursion.
                      would a fuse be an appropriate measure?

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                      • #12
                        Fuses aren't precise enough, especially as they're current limiters, and current varies with impedance, which varies with frequency. A limiter holds the amp's maximum voltage output where it can't cause either mechanical or thermal damage, and voltage is a constant into any impedance load. Of course you have to know what the safe voltage limit is, and not all designs provide that.
                        www.billfitzmaurice.com
                        www.billfitzmaurice.info/forum

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                        • #13
                          Meaning a limiter before the amp's input stage?

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                          • #14
                            Originally posted by hardcorecap View Post
                            Meaning a limiter before the amp's input stage?
                            Yes. This may help:
                            http://billfitzmaurice.info/forum/vi...hp?f=14&t=8755
                            www.billfitzmaurice.com
                            www.billfitzmaurice.info/forum

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                            • #15
                              thanks bill!

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