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Thread: Is my sub blown?
05-29-2013, 09:35 AM #1
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
05-29-2013, 11:03 AM #2
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.
05-29-2013, 11:40 AM #3
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
05-29-2013, 12:02 PM #4
05-29-2013, 12:21 PM #5
Newty made a good suggestion. Definitely try that also.
05-29-2013, 12:37 PM #6
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.2012 LSV
05-29-2013, 01:00 PM #7
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.
05-29-2013, 07:39 PM #8
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
05-31-2013, 06:12 PM #9
So the sub is blown, now on the task of getting a replacement. Thanks guys for all your help!!2012 LSV
05-31-2013, 08:50 PM #10
Look at the bright side. Now you have nice passive radiator.