A background rumble appears in a sound from microphone in Sound blaster Live.

Discussion in 'Computer Support' started by D, Oct 15, 2007.

  1. D

    D Guest

    Hello!
    A background (about 50hz) rumble appears in a sound from microphone.
    Windows XP SP2.
    I tried two headsets (which surely are good). The rumble decreases if
    I touch the computer case. I checked the inside of the case, did not
    find any improper contacts. The sound card is Creative sound blaster
    live ct4830. I tried the latest Microsoft and Creative drivers. The
    Creative driver does not output sound from microphone to speakers at
    the same time, but only from a recording from the microphone. How to
    prevent the rumble?
    Best regards,
    Dima
     
    D, Oct 15, 2007
    #1
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  2. "D" wrote ...
    In common use, "rumble" applies to low frequency *random noise*
    such as from an air duct or a subway train or from a distant highway.

    If you are hearing interference from your power mains (presumably
    50Hz if you are posting from Russia), that is called "hum" and it is a
    very *constant* tone.

    We will assume that you mean that you are hearing interference
    from power-line hum. If it is *rumble*, then it is acoustic and you
    should be able to hear it with your ears, no headset, no computer.
    Does it hum when no headset is plugged in?
    If so, then there is a problem with the computer or sound card.
    If no, then *both* of your headsets have a problem

    Does the hum change when you move the headset around
    the room?

    Does it hum when you try using a differen computer mic?

    rcrowley posting from rec.audio.pro
     
    Richard Crowley, Oct 15, 2007
    #2
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  3. Is "rumble" a precise term or are we chasing a mains hum?
     
    Laurence Payne, Oct 16, 2007
    #3
  4. D

    thanatoid Guest

    IMO, this undoubtedly means you have a ground problem. As if
    "about 50 Hz" was not enough of a tipoff. It's always 50 or 60.

    But it MAY just be a totally crappy microphone. Try another one,
    preferably a good one.

    If it's NOT the microphone, I am not a technician so I can't
    tell you how to fix it, but first thing you should do is check
    that everything to do with you system is plugged into the SAME
    AC circuit, preferably same outlet with power bar(s), and then
    you can buy or borrow (or steal I suppose) a little gizmo which
    you plug into the wall outlet and it tells you if everything's
    OK. Other than that, ask a technician.
    That si impossible. Check your mixer volumes, mutes etc.
    Watch out for feedback, it can be VERY unpleasant, but no sound
    card manufacturer will disable mic to speakers direct just
    because of that.
     
    thanatoid, Oct 16, 2007
    #4
  5. D

    kráftéé Guest

    What are you recording, I know you state form a microphone, but are
    you plugging in something else into the microphone socket? If so that
    would be the problem try plugging it into the line in socket.

    If it is a microphone then make sure that it is being fully pushed
    home, if it is then try another one (they aren't exactly expesinve).

    Others have mentioned ground loops etc, but try the easy bit (normally
    the cheapest bits) first.

    As a matter of fact I get a continual low level 50hz hum from my line
    in post unless I actually plug something into it then it dissapears,
    so you could also try turning off all ports you are not using before
    doing your recording.
     
    kráftéé, Oct 16, 2007
    #5
  6. D

    D Guest

    Thanks Richard Crowley for your explanations!
    It does not hum when no headset is plugged in.
    One of the headsets is brand new and checked.
    Yes, the hum changes when I move the headset around the room: the
    further from the computer case the louder.
    Yes, it hums when I try using a differen computer mic: both headsets.
     
    D, Oct 16, 2007
    #6
  7. D

    D Guest

    Yes, we are chasing a mains hum.
     
    D, Oct 16, 2007
    #7
  8. D

    D Guest

    Thanks thanatoid for your suggestions!
    I checked my mixer volumes, mutes etc. and did not find anything
    wrong. I uninstalled the Creative driver.
     
    D, Oct 16, 2007
    #8
  9. D

    D Guest

    Thanks kráftéé for your suggestions!
    I checked with brand new headset - the same.
     
    D, Oct 16, 2007
    #9
  10. "D" wrote ...
    Then you can eliminate any problem with the computer,
    the sound card, or any software including drivers, etc.
    What does "checked" mean? Do either of the headsets work
    OK on another computer?
    I would take a wild guess that it has a shielding or grounding problem.
    The problem may be with the basic design if both headsets
    show the same symptoms.
     
    Richard Crowley, Oct 16, 2007
    #10
  11. D

    thanatoid Guest

    Sounds like it's not the mic, but you may have a short of some
    kind or ground loop in your headphone connection. If the
    headphone connection is at the front of your machine, a
    technician has to check it.

    If it's a jack on the soundcard, you can remove the sound card
    and take it to a technician without having to take the whole
    computer over there.
     
    thanatoid, Oct 16, 2007
    #11
  12. D

    D Guest

    Theanks Richard Crowley for your suggestions!
    The hum is from speakers, not from the case. Yes, either of the
    headsets work OK on another computer.
     
    D, Oct 17, 2007
    #12
  13. D

    D Guest

    Thanks thanatoid for your suggestions!
     
    D, Oct 17, 2007
    #13
  14. D

    D Guest

    Thanks Richard Crowley for your suggestions!
    The hum is from speakers, not from the case.
    Yes, either of the headsets work OK on another computer.
     
    D, Oct 17, 2007
    #14
  15. D

    Bob I Guest

    The problem is likely caused by the combination of "speakers" being
    disconnected by the insertion of the head phones AND the volume knob of
    the speakers being cranked up rather high. Now the speakers are
    amplifying the hum of the little power wart.
     
    Bob I, Oct 17, 2007
    #15
  16. D

    D Guest

    Thanks Richard Crowley for your suggestions!
    The hum is from speakers, not from the case.
    Yes, either of the headsets work OK on another computer.
     
    D, Oct 17, 2007
    #16
  17. Then it is possible that the sound card has a problem.
    Since the sound card feeds power into the microphone in
    the handset, the filter capacitor on the microphone power
    may have a problem that is letting 50Hz hum get injected
    into whatever microphone is connected. You would not
    hear this unless a microphone was connected. Since the
    headsets work OK on another computer, that casts the
    suspicion back on the sound card.
     
    Richard Crowley, Oct 17, 2007
    #17
  18. Perhaps the sound card just has the problem that it's a Soundblaster
    Live! and you're using the mic input. A SB's Line in/out is
    acceptable quality but the mic input is a joke.
     
    Laurence Payne, Oct 18, 2007
    #18
  19. D

    thanatoid Guest

    You're welcome and good luck. Check if a new sound card isn't
    cheaper than fixing yours!
    Creative is basically OK and ultra-compatible although
    perfectionists complain about the sound/specs.
    M-Audio if you're a musician or have very good ears.
    Turtle Beach is pretty good too if you can find one.
     
    thanatoid, Oct 18, 2007
    #19
  20. D

    D Guest

    Thanks Bob I for your explanation!
    How can the speakers amplify the hum of the little power wart if they
    are disconnected by the insertion of the head phones?
    A Sony ECM-T6 microphone and another desk-top microphone don't hum! A
    new Koss sb/45 headset and Philips SBC HM300 headset hum from their
    microphones.
    How to make Koss sb/45 headset microphone work?
    Best regards,
    Dima
     
    D, Oct 18, 2007
    #20
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