Subwoofer buzz

By dregon99
Jan 7, 2011
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  1. Hello. I just bought a new 2.1 system from logitech, Z523. The system works fine but i noticed that when the system is turned off the subwoofer makes a buzz but you can hear it only if you are very very close to it.
    The strange thing is that when i turn the system on is stops making that noise. Anyway the noise doesn't bother me because you can hear is only when you stay with your ear next to it, but i was curious if this is something normal. Anyway the system sounds fine, the only thing is when i turn the volume to maximum there is noise in the speakers but thats normal from interferences right?
  2. jobeard

    jobeard TS Ambassador Posts: 13,336   +293

    Is the subwoofer powered by A/C from the wall?

    The symptom sounds like a broke ground (common/lead) to an active amplifier.
    When the system is actice, the speaker lead is grounder by the computer but when
    not running, the amplifier is still left active and the center lead is an antenna.
  3. Benny26

    Benny26 TechSpot Paladin Posts: 1,575   +47

    Yes that's right.
  4. dregon99

    dregon99 Newcomer, in training Topic Starter

    Thanks for the answers. Yes the subwoofer is powered by A/C from the wall. And should i worry about this jobeard? Should i ignore it as long as it doesn't affect the sound or should i go with the system at Warranty? Thanks in advance.


    Btw is it possible to be from the A/C outlet from the wall not being grounded? actually i am not sure if is grounded or not. And also the system is not connected directly to the A/C outlet from the wall, its connected to a extension cord that is connected to the A/C outlet form the wall, and i also have the computer connected to the extension cord.
  5. Benny26

    Benny26 TechSpot Paladin Posts: 1,575   +47

    This is the exact setup as i run mine.

    The A/C plug that runs my subwoofer is fitted with an earth, as almost all UK plugs are fitted with one by standard. If you live in the US though, i'm not sure.
  6. dregon99

    dregon99 Newcomer, in training Topic Starter

    Well i live in romania and we don't have like that. The plug has 3 pins right? Here it only has 2.
  7. jobeard

    jobeard TS Ambassador Posts: 13,336   +293

    yes
    absolutely!
    extension cords are a bad idea. At least use a surge protector - -
    and this requires a ground/earth conneciton.
  8. dregon99

    dregon99 Newcomer, in training Topic Starter

    Thanks for the answers.


    Another thing i noticed today is while i was staying with the ear near the subwoofer to hear that noise i unplugged the system and the noise doesn't stop as soon as i unplug them, it still makes the noise for another 3 seconds and dimming out from the high frequency when it was plugged to low till it stops.
  9. Benny26

    Benny26 TechSpot Paladin Posts: 1,575   +47

    That's only because after you've unplugged something, there's still some power in the electrical cord that's being given to the subwoofer...It's only normal.
  10. jobeard

    jobeard TS Ambassador Posts: 13,336   +293

    LOL :eek:

    Can't be true fella. The slow decay is the capacitor draining of all charge left
  11. Benny26

    Benny26 TechSpot Paladin Posts: 1,575   +47

    Ah yes, my mistake. I must be more pedantic in the future.
     


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