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  1. #1

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    Unhappy HELP! low freq hum on the sub

    just noticed a low frequency hum on my sub. hums even if i disconnect the subwoofer cable. if i touch the imputs with my finger, the hum diminishes slightly. the volume and crossover settings have no effect on the hum. if i turn the phase control to 0, (all the way to the left), the hum gets louder. if i turn it to 180 degrees, the hum gets much lower in volume (but still there). I changed the power cable with no change. cant be a ground loop since it does it even when disconnected from the sub cable.

    please help, this is driving me nuts, do i need a new plate amp?

    i use a parts express 250W plate amp (the one without the bass boost i believe) if this helps


    desperatly
    Lou
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  2. #2

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    Sounds like the amp has an issue, if it sits their and hums even without an input.

  3. #3

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    funny thing is, if i jiggle the input jacks, sometimes the sound goes away. wierd. also, if i touch the top of the plate amp, the sound goes away too. ???
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  4. #4

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    WTF???? sound is gone, jiggled the jacks yesterday as noted below, and today, no noise. oh well, i guess i should be happy.

    my guess now that it is a ground issue since i was able to touch the amp with my finger in some places (on the outside of course) and the sound went away

    friggin wierd!

    at least all is well

    thanx for the help anyway :)
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  5. #5

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    Thumbs up

    Thanks
    I was keeping the subwoofer on the carpeted floor in my apartment. I kept it on a table just to test and its silent now. thats such a relief.

  6. #6

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    Sorry I replied to the wrong thread.
    I noticed a very low hum from my sub and its silent after I put it on a platform instead of on the carpet.

  7. #7

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    [QUOTE=ohskigod]WTF???? sound is gone, jiggled the jacks yesterday as noted below, and today, no noise. oh well, i guess i should be happy.

    my guess now that it is a ground issue since i was able to touch the amp with my finger in some places (on the outside of course) and the sound went away
    QUOTE]

    Definitely sounds like a grounding issue. If jiggling the jacks took care of it it may be a bad shield on a cable or on the jack. If it returns check the shield connections on the jacks internally or with a multimeter. Might check the resistance end to end on the low side of the cable. Flex the cable while taking the measurement and watch for changes in the value.
    The Family
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    Do not one day come to die, and discover you have not lived.
    This is pretty f***ed up right here.

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