Subwoofer hum

Discussion in 'General Electronics Chat' started by pyler, Apr 23, 2015.

  1. pyler

    Thread Starter New Member

    Oct 9, 2012
    2
    0
    Whenever I plug the power cord and the speaker cable in my laptop there's a hum that can be heard in the subwoofer. However, when I take out the power cable, it goes away. It also goes away whenever I plug in a VGA cord into the laptop (with the power cable plugged in as well.)

    Why does this happen?
     
  2. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
    2,804
    1,237
    Ok, this is merely a 'shot in the dark'... It seems as the hum is introduced by the PS (60Hz crosstalk 'through' the SMPS...) --- Perhaps capacitance in the VGA cable (or VGA display if connected) filters off or cancels said noise...

    Responses to the following would be helpful:

    1) Is the hum present when the the power cable is attached to the laptop but disconnected from the mains?
    2) Is the VGA cable 'open'? -OR- Is 'the other end' connected to a VGA device?

    Best regards
    HP
     
    Last edited: Apr 23, 2015
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