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Subwoofer hum. Is it normal?

Discussion in 'Subwoofers' started by vep, Sep 10, 2003.

  1. vep

    vep
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    I have a JMLab SW 800 subwoofer. If i put my ear next to the driver in can hear the driver humming. I't is not very loud but i can hear it if i am very close to the sub and there are no other sound in the room. The humming is heard even when everyhting else is disconected from the sub (amp to sub connection disconnected) and everything is shout down except the sub. What i would like to know is if small amount of humming sound is normal or there should be none at all?

    Thanks
     
  2. Dom36

    Dom36
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    I get hum from the left front speaker - it's the amp though...
    You got another sub you can try out on the amp to find out whats the problem???
     
  3. alexs2

    alexs2
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    Sounds very much as if this is hum inherent to the sub itself,i.e.via it's own electronics.....does the sub have a switch to lift the earth connection as some do....lifting the earth connection may remove the hum if that is possible,although this isn't something that should be done without removing all other possible causes.
     
  4. Bernard Barnett

    Bernard Barnett
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    My M&K sub hums in exactly the same way as Vep describes. I think it's normal. Certainly doesn't bother me.
     
  5. nathan_silly

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    Mine too (Rel Storm) just audible when your put your ears near to the cone.

    If it was audible from your listening position (or several feet away) with the sound muted I would worry about it.
     
  6. bob1

    bob1
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    Mine hums aswell.
     
  7. dts_boy

    dts_boy
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    my sub hums and can be heard anywhere in the room. i called the manufacturer and they said it was normal, but they would send a new power amp to my dealer to try and fix the problem. this means taking my sub in and as the thing weighs over 55Kg i decided not to bother as i have actually gotten used to it now and in no way affects the performance!
     
  8. hamtaro

    hamtaro
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    my velodyne vx 10 has a faint hum.and it is very very faint. i switched the sub of at the wall, and left it off for a day[its been in standbye for 3 months and the hum has calmed down a lot
     
  9. menalaus

    menalaus
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    this from Kef Ben may prove helpful
    Dear Sir,

    System hum is not necessarily caused by defective products but usually an earth or ground loop.
    Ensure that both subwoofer and amplifier are using the same wall socket.
    A surge protected, RFI filtered gang strip can be useful for powering the whole system.

    A simple mains hum remedy is grounding/earthing the subwoofer back panel to the amplifier.

    Most amplifiers have a GND (ground or earth) terminal on the back panel for this purpose.
    This Ground terminal can be connected to a small diameter electrical cable (bell wire) between this terminal and the subwoofer back panel.

    Carefully remove one of the outer screws on the Subwoofer amplifier panel, remove a small amount of paint (under screw head) in order to make a reliable electrical connection.

    A small ring crimp can be used to terminate the cable on the subwoofer panel.

    Once the Amp and subwoofer are connected, all hum should be eliminated (as they now have the same potential).
    It is also worth noting that the hum may be caused by other devices such as DVD player (if a coax cable is used), or more commonly, a TV aerial or cable TV decoder.
    (A ground loop isolator can be used on the incoming cable TV line if this is the cause of hum).


    Please contact me on (01622) 672261 if you would like to discuss this solution.

    Best Regards

    Ben Pettit

    KEF AUDIO (UK)
     
  10. Bernard Barnett

    Bernard Barnett
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    I followed these instructions and it worked a treat - no hum! Thanks for posting Menalaus.
     
  11. Cool-hand

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    1 x (in-line) ground loop supressor required via maplins @ £4.99 should cure your ills.

    S.


    For croniclly humming subs 1x remove old egg sandwich from unit!
     
  12. vep

    vep
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    To sumarize. Can we say that a small amount of hum is something normal?
     

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