sub hum

Discussion in 'Subwoofers' started by bigdunc, Mar 18, 2004.

  1. bigdunc

    bigdunc
    Standard Member

    Joined:
    May 28, 2003
    Messages:
    99
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Ratings:
    +2
    Can anyone help?
    I have a MS208 sub which has started to emit a
    fairly loud humming noise for the last 2 weeks or
    so.

    I've had it for about 3 months and haven't had
    any problems until now.I've plugged the amp and sub into
    the same socket and changed the lead but no joy

    Any ideas?
     
  2. chrisgeary

    chrisgeary
    Well-known Member

    Joined:
    Jul 23, 2003
    Messages:
    2,771
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newbury
    Ratings:
    +254
    presumably the hum disappears if you disconnect the line level feed to from the amp to the sub? if so, you may have a ground loop. You don't say what your AV amp is, but the chances are that it needs to be earthed. Your AV system should have one system earth somewhere. Many components are only wired with 2 core mains cable as they dont need to be earthed for electrical safety.
    I had this a while back - what I did was make up a single core lead (a bit of bell wire will do), wired it into a standard 13A plug to the earth pin. Plugged it in (this is safe as you are only using it as an earth!) and connected it to the phono grounding point (my 3803 at the time had a phono input with ground poing) and hey presto the hum disappeared.
     
  3. tuftus

    tuftus
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I also have a humming MS308 sub, I have replaced the phono lead for a better quality one but it has made no difference.

    My AV amp is a Yamaha DSPAX640SE but I cannot see anywhere additional earths can be added.

    Any clues on this one as I would love to get to the bottom of it?

    Tuftus
     
  4. chrisgeary

    chrisgeary
    Well-known Member

    Joined:
    Jul 23, 2003
    Messages:
    2,771
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newbury
    Ratings:
    +254
    first, let's be clear. does the sub only hum when connected to the AV amp? how loud is the hum, is it background or is it as loud, or louder than the audio its being fed with?
     
  5. mw3cdj

    mw3cdj
    Standard Member

    Joined:
    Nov 12, 2002
    Messages:
    399
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    West Wales
    Ratings:
    +1
    I to use to suffer from 50Hz sub hum , i solved it by running a separate earth to a new earth rod i drove into the ground just outside my room. A little OTT maybe , but i have nearly all my av rack earthed to it now.

    Daran
     
  6. bigdunc

    bigdunc
    Standard Member

    Joined:
    May 28, 2003
    Messages:
    99
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Ratings:
    +2
    My amp is a Denon 2802,if I disconnect
    the lead the hum disappears
     
  7. chrisgeary

    chrisgeary
    Well-known Member

    Joined:
    Jul 23, 2003
    Messages:
    2,771
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newbury
    Ratings:
    +254
    right-o. does the hum disappear if you have the sub connected to the denon, but the amp is off?

    also does it disappear if you turn the volume on the amp down to infinity?

    also, does it disappear briefly whilst changing sources?
     
  8. bigdunc

    bigdunc
    Standard Member

    Joined:
    May 28, 2003
    Messages:
    99
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Ratings:
    +2
    A- No

    B- No

    C- No

    If I switch the sub off at the back the main
    humming noise disappears but a very faint hum
    can be heard from the rest of my speakers.
    Only if I disconnect the lead does all hum disappear
     
  9. rozzar

    rozzar
    Active Member

    Joined:
    Sep 29, 2002
    Messages:
    1,056
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    41
    Location:
    Braintree
    Ratings:
    +23
    use a proper screened subwoofer lead
    like Black Rhodium First Base or Ixos Gamma XHW406

    next, buy a good quality Mains cable. Start from £50 :)
     
  10. chrisgeary

    chrisgeary
    Well-known Member

    Joined:
    Jul 23, 2003
    Messages:
    2,771
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Newbury
    Ratings:
    +254
    hmm, sounds like your sub is the source of the hum. with the sub off, does it disappear if you disconnect it from the wall completely?
    might be a bad earth on the subs mains connection. other than that, im outta ideas.
     
  11. bigdunc

    bigdunc
    Standard Member

    Joined:
    May 28, 2003
    Messages:
    99
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Ratings:
    +2
    Not sure if you misread what I said.
    If I take the phono lead out of sub the
    humming stops,switched on there is no problem.

    Not sure if this is a factor or not but when I
    got my sub a few of my cable channels were off air.
    I wasn't too bothered so left it for a couple
    of months.An engineer eventually came and fixed it, but later
    that day the humming started.

    Could this be the cause of the problem and if so
    what do I do?
    Thanks for your time.
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice