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  1. #1
    Join Date
    Apr 2010
    Location
    Hattiesburg, MS
    Posts
    54

    Default Is my sub blown?

    We were wake boarding everything sounded fine. The song changed it was a bad quality song and sub was making a rattling sound. Before I could turn it down it quit working and hasn't worked since. It's a 10" JBL the amp is JBL as well. I noticed the amp has a orange light on the front. I don't know if its supposed to be orange or green. Maybe someone with more knowledge can help out. Does it sound like I blew it or is there a safety that shut it off?
    2012 LSV

  2. #2
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Quote Originally Posted by Grady View Post
    We were wake boarding everything sounded fine. The song changed it was a bad quality song and sub was making a rattling sound. Before I could turn it down it quit working and hasn't worked since. It's a 10" JBL the amp is JBL as well. I noticed the amp has a orange light on the front. I don't know if its supposed to be orange or green. Maybe someone with more knowledge can help out. Does it sound like I blew it or is there a safety that shut it off?
    Grady,
    If the sub is toast, the amplifier may only be in the protection mode.
    First, lightly and evenly push in on the center of the subwoofer cone. If the woofer is not compliant and frozen then the sub is gone. If you apply pressure evenly you should not feel/hear an internal rubbing although any imbalance in pressure can cause some internal friction. If the rubbing is very apparant with very little push then the sub is gone. If the sub passes this test then remove the sub. Measure the voice coil DCR with a multimeter. The DCR should be 80 to 100% of the woofer's stated AC impedance. If the voice coil is either 'open' or the DCR reads inordinately low then the sub is gone. You can also apply a very short term pulse across the woofer terminals with a small 9V battery.
    Check the woofer connections and check the braided leads from the woofer terminals that run to the woofer cone/internal voice coil.
    If all that passes move upstream to the amplifier. That can be a later discussion.
    Generally a foriegn 'rattling' sound before failure is an indication of the speaker.

    David

  3. #3
    Join Date
    Apr 2010
    Location
    Hattiesburg, MS
    Posts
    54

    Default

    David
    The sub moves freely, but as I lightly push the cone I hear a squeaking sound as I push. Is this rubbing you speak of?
    2012 LSV

  4. #4
    Join Date
    Mar 2008
    Location
    Vancouver WA
    Posts
    2,592

    Default Re: Is my sub blown?

    Quote Originally Posted by Grady View Post
    David
    The sub moves freely, but as I lightly push the cone I hear a squeaking sound as I push. Is this rubbing you speak of?
    Pretty good chance that's it and the sub is done. Unplug the sub from the amp and see if the orange light goes away. That would definitely point to the sub.

    Sent from my iPhone 5... ya right!


    PWI as usual...

  5. #5
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Quote Originally Posted by Grady View Post
    David
    The sub moves freely, but as I lightly push the cone I hear a squeaking sound as I push. Is this rubbing you speak of?
    If you equally apply the pressure on both sides of the cone as to not rock the cone, then you should not make any voice coil contact. Spread your index finger and thumb from both hands to have four points of contact. Practice on a coaxial to get a better feel which will have an even tighter gap. Rubbing is a bad sign.
    Newty made a good suggestion. Definitely try that also.

    David

  6. #6
    Join Date
    Apr 2010
    Location
    Hattiesburg, MS
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    Default

    I tried it again still same sound as soon as I apply a little pressure. It doesn't sound like a rub, sounds like it needs to be oiled. lol Not sure if its the same sound your talking about.

    I unhooked the sub turned the amp on, ensured loose wires were not touching and still has orange light. I took a pic of the amp so you can see if it supposed to be a different color. I have never paid attention to the amp colors til now.
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    2012 LSV

  7. #7
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Grady,
    I don't know that amplifier. Check in the manual for the various status LED conditions. If you don't have the manual then do a search on-line.
    It's possible that the amplifier failed and took out the woofer. So I don't want you to substitute another speaker just yet to test the amplifier. Proceed this way. Raise the amplifier crossover frequency as high as it will go. Eliminate any bass boost or EQ. Use a non-polarized 47 mfd. capacitor (makes no difference as to the + or - lead) on a coaxial or any speaker to test. This will save the test speaker if the amplifier misbehaves. Easy does it. If you get any music the amplifier may be okay. If you get nothing then that may be more bad news.
    For any meaningful diagnosis you must first verify that you have a healthy supply voltage at the amplifier primary terminals, and that you have a signal at the input.
    If you have a multimeter, I cam give you other methods of checking the amplifier.

    David

  8. #8
    Join Date
    Apr 2010
    Location
    Hattiesburg, MS
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    54

    Default

    I looked through manual and all the light are showing normal. I'm back to thinking its the sub. I have a multimeter at work so ill check it out tomm.
    2012 LSV

  9. #9
    Join Date
    Apr 2010
    Location
    Hattiesburg, MS
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    Default

    So the sub is blown, now on the task of getting a replacement. Thanks guys for all your help!!
    2012 LSV

  10. #10
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Look at the bright side. Now you have nice passive radiator.

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