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Strange noise from my subwoofer!!

Discussion in 'Home Cinema Speakers' started by esoxcrazy, May 27, 2004.

  1. esoxcrazy

    esoxcrazy
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    I have the Acoustic Energy AEGISEVO 3B package an every now and again when watching a film in surround sound a noise comes from the sub. The noise only sounds when not much is happening in the film, it’s very difficult to explain sort of a knocking sound. Does anyone now what this could be.
     
  2. Nimby

    Nimby
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    Knocking sounds like the driver cone bottoming out. There may be subsonic effects added to the film for tension and drama. Is it at exactly the same place on the film every time? Only one film? Or all of them?

    Some effects may be too low for your sub to reproduce. So the cone just flops back and forth out of control. This is only a wild guess though.

    Curious. Doesn't this knocking happen on loud bassy bits at all? Or could it be drowned out by the rest of the 'racket' going on at the same time?

    Nimby
     
  3. esoxcrazy

    esoxcrazy
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    thanks for getting back to me. The noise seems to happen on all films at various times. I do notice the noise when not much is happening on the film.It seems to happen even if i'm not watching anything and the sub is left on.
     
  4. Brimstone

    Brimstone
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    Exos,

    I don't know how often this noise occurs, and so whether the below suggestions
    will help much (not if its a very occasional 'knock').

    [1] Check - Is it definately making this noise even when no films are being
    shown?

    If you're sure - try disconnecting the signal inputs from the AV amp - does it
    still make the noise?

    If it stops - it could be noise on the sub output signal from the AV amp (would
    be unusual, but possible). Or broken/loose connection on the RCA/phone cable
    (movement or low bass in the room causing it to move fractionally and
    'crackle/pop' now and again). You could try waggling the phono cables fully
    along its length and see if the noise occurs (when connected to amp).

    If you try using the front speaker terminals on the high input of the sub and it
    doesn't re-occur - its the AV amp sub output or the phono lead.

    If you're still getting the noise - its the amp/sub (or power lead). Try
    waggling the power cable along its length as well - noise occurs? If yes -
    Check power socket on sub, then replace the power cable with another from
    somewhere (kettle lead type?) - still noise?

    If it still makes the noise with no input, and power cable replaced and socket
    checked - most likely something dodgy with the built in amp/pre-amp/crpsover (im
    assuming this AE sub is active). Any number of different faults in the amp and
    its input circuitry could cause noise (the sub speaker's only capable of
    producing low frequencies anyway so, doesn't narrow it down to before the
    crossover). If so - is it still under warranty? If not - are there any
    qualified audio repair shops near you?

    [2] If it makes noise at any time only when films are on - you're looking at the
    AV amp, or the previously mentioned extra low sound effects (although you state
    its not just a loud parts, but quiet parts as well...) causing bottoming out,
    or its the sub/amp.

    [3] Another thought - have you tried the Engineers method - giving the sub box a
    good thump - any effect? loose parts/wiring inside?

    Tell us how you get on.

    P.S. The knocking sound isnt the neighbours banging the walls and tellin you to
    turn that racket down is it?... Gotta love the bass.

    Cheers, Mark.
     
  5. karkus30

    karkus30
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    Could it be the rattle of the amplifier relay, maybe the sub is switching off because its no longer getting an LF signal for long periods of time. Incorrect bass settings on the amplifier? broken leads?

    Maybe the drive unit is damaged due to overdriving the sub? or loose fastenings on the drive unit?
     

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