Help'!! Subwoofer is "crackling"

Discussion in 'Archived Threads 2001-2004' started by Prathavan V, Dec 18, 2002.

  1. Prathavan V

    Prathavan V Stunt Coordinator

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    One of my best friends has a Sonance "The Sub" THX subwoofer. It's listed under "inwall speakers on Sonance's homepage. The problem, besides the fact that it's out of warranty....

    When the sub is reproducing sounds (literally any sounds as the crossover only seems to induce MORE crackling the higher it is set), the sub "crackles". I don't know how better to describe this. It sounds like it's cracked or like there is something rattling around in there.

    We figured it was the speaker, so it was removed, and just to make sure it wasn't the cabinet, it was tried while outside of the cabinet. Still rattles.

    Got a new 12" sub driver just to check it out (and see what it sounded like), but the rattling (crackling) is still there!! To our minds, that would rule out the speaker being the problem!! Luckily that speaker is returnable. So what else could it be? Electronics in the crossover, the amp??

    It's not a dust kind of noise that you sometimes get fiddling with the volume on older equipment, it's just a rattle or a crackle kind of sound. It honestly sounds like a piece of metal rattling or a broken woofer cone or something like that. I don't think that it got any louder with increased volume...

    To make a long story short....HELP!!! Any ideas for troubleshooting would be greatly appreciated. Thank you all in advance.
     
  2. Robert_Gaither

    Robert_Gaither Screenwriter

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    I think I'd check the housing and the mounting hardware to see if maybe they were either damaged (maybe during the install and with time it shook itself apart) or came loose.
     
  3. Prathavan V

    Prathavan V Stunt Coordinator

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    Robert, thanks for the reply.

    We actually tried the driver OUTSIDE of the cabinet, so the rattle "sound" was definately not caused by the sub box, but rather the speaker itself. Also, with the NEW driver, outside of the box, the "rattle" continued which led us to believe that it was an electrical "sound" being created in the speaker.

    We even brought over my sub and tried that, to see if it was the LFE out on the receiver, but my sub has not reproduced any such crackling or rattling. By the process of elimination, it's therefore not the LFE output, and, since the rattle occured with two different 12" subs OUTSIDE the box, it's not the sub driver. That leaves the subs amplifier, the crossover and other internal electronics in the box as being the culprit in causing this "new" electrical signal. At least that's the best I can deduce. I can't think why any of those would cause such a "rattle" or "crackle" (click??) to be reproduced in the speaker.

    Geez, I'm confused reading my descriptions, but I hope it's clear enough for you guys to decipher.
     
  4. Edward J M

    Edward J M Cinematographer

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    You pretty much answered your own question. It's not the LFE signal, it's not the driver, and it's not the enclosure. Your logic in troubleshooting seems bullet proof. Next step: Replace the amp with a new OEM unit, or a generic subwoofer plate amp from Parts Express, etc. Good luck.

    Ed
     
  5. Evan S

    Evan S Cinematographer

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    Prathavan, what electronics are you using? If you are running the sub off the Anthem AVM-20 (which I know you own), then the Anthem may be the problem.

    I'm sure you've probably heard, but maybe not, that the 2.07 software code is buggy and will induce a popping sound on stereo source material that contains a large amount of bass. Upgrade the software to version 2.08 to remove the problem. Otherwise, I have no clue.
     
  6. Prathavan V

    Prathavan V Stunt Coordinator

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    Thanks Evan, but it's not off my Anthem (and I'm still running 2.06). My friend has a Pioneer Receiver (I think its a 45 or 47 - something like that).

    Ed, I've never heard a 'broken' amp before! I guess we'll try that next. We should be able to test it by using an outboard amp right?? Do you think it could be a ground wire or something shorting on the plate amp?

    If a new amp doesn't resolve the problem, I'll let y'all know.
     
  7. Edward J M

    Edward J M Cinematographer

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    Sure - amps go bad sometimes. When you take the OEM unit out, look for the obvious - cracked or chaffed wires, loose connections, etc. But it could also be a thermally related break-down or outright component failure of the solid state electronics in the plate amp itself.

    Ed
     

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