Hum from LSi25 speakers (even without any cables connected)

wowbagger1234
wowbagger1234 Posts: 5
edited July 2012 in Troubleshooting
Hi - recently bought LSi25 speakers, but i get a 60Hz hum coming from each of the subs, even when the speaker wires and LFE input are disconnected (so I've ruled out any amplifier issues, CATV ground loop issues, etc). The hum only goes away when I unplug the speaker. I've used a pair of Hum X filters http://www.amazon.com/gp/product/B0002E4YI8/ref=oh_details_o03_s00_i00 but it hasn't made any difference. I've also tried using different outlets.

Any suggestions would be appreciated.

Thanks,

Chris
Post edited by wowbagger1234 on
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Comments

  • VR3
    VR3 Posts: 28,641
    edited June 2012
    Sounds like a ground loop... do the amplifiers have a 3 prong plug on the LSi25?
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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  • wowbagger1234
    wowbagger1234 Posts: 5
    edited June 2012
    Hi VR3 - the in-speaker amplifiers have polarized 'one way' two prong plugs....
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  • VR3
    VR3 Posts: 28,641
    edited June 2012
    Hmm...

    How loud is the hum? Like over bearing or just a faint hum?
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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  • wowbagger1234
    wowbagger1234 Posts: 5
    edited July 2012
    VR3 wrote: »
    Hmm...

    How loud is the hum? Like over bearing or just a faint hum?

    It's loud enough that I know it's there from 10 feet away, although it's almost 'ambient' at that distance. When there is a signal it's not noticible, even when I put my ear right up to the back of the speaker where the noise is apparently coming from.
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  • arny
    arny Posts: 37
    edited July 2012
    wowbagger1234 wrote: »
    Hi - recently bought LSi25 speakers, but i get a 60Hz hum coming from each of the subs, even when the speaker wires and LFE input are disconnected (so I've ruled out any amplifier issues, CATV ground loop issues, etc). The hum only goes away when I unplug the speaker. I've used a pair of Hum X filters http://www.amazon.com/gp/product/B0002E4YI8/ref=oh_details_o03_s00_i00 but it hasn't made any difference. I've also tried using different outlets.

    The hum would appear to be coming from the LFE speaker. Since this input is designed to be driven by a low impedance source, it is appropriate to test it with a shorting plug inserted. You can fabricate one of these by cutting an interconnect in half, stripping the insulation and tightly twisting the signal wire and shield together.

    If you still have a hum that you can faintly hear even across the room, it would appear that the speaker has a technical problem.
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