Buzz-like Whine when Recording with USB Audio Adapter

Discussion in 'Mac Accessories' started by cleanup, May 16, 2006.

  1. cleanup macrumors 68030

    cleanup

    Joined:
    Jun 26, 2005
    Location:
    Toronto
    #1
    I purchased a small USB audio adapter so I could use a stereo microphone with my iMac without needing phantom power. Plus I would get higher quality recording.

    It worked brilliantly the first time. Clear sound, no background noise or interference.

    I unplugged the audio adapter for a bit and then later I went back to record.

    Now when I record there is this buzz-like high-pitched whine that comes through all the time (you can hear it after recording and if you turn on the audio monitor)... it can still pick up other noises but the entire thing is permeated by the whine.

    As soon as you either switch off the microphone or unplug it the whine disappears. This occurs on both my stereo headset and an XLR microphone I've tried with an adapter. Both can record fine, but there is the high pitched whine over top of it. What's interesting is there is no whine when recording with the little microphone in the iPod earbuds or my Sony earbuds.


    If I unplug the microphones, and press my finger to the audio in port on the adapter or hold my hand anywhere near the adapter, the whine returns. I take my finger off or pull my hand away, and it fades away.

    The whine only comes out of the left speaker (or headphones if I plug in headphones)... in fact, for some reason, it won't record through two channels, or my iMac isn't playing out of one channel.

    It worked perfectly the first time. What the hell is causing the whine and how can I get rid of it?? I need to record!

    [Edit]: here's a recording of the whine.
     
  2. bigboy99 macrumors 6502

    Joined:
    Nov 12, 2005
    Location:
    Deep in the Heart of Tejas
    #2
    This symptom is a sign of a grounding problem.

    "If I unplug the microphones, and press my finger to the audio in port on the adapter or hold my hand anywhere near the adapter, the whine returns. I take my finger off or pull my hand away, and it fades away."

    Recheck your connections. The problem may have occured when you disconnected.
     
  3. cleanup thread starter macrumors 68030

    cleanup

    Joined:
    Jun 26, 2005
    Location:
    Toronto
    #3
    A grounding problem? As in the power plug?

    How do I fix it?

    I've checked my connections dozens of times. earlier today the buzzing wasn't so bad and was more of a high-pitched ringing that intermittently came in and out. Now the buzzing has returned (seems to occur later in the day)...

    I've even tried using different USB ports, including the ones on the keyboard, to no avail.

    How do I fix the grounding problem?
     
  4. cleanup thread starter macrumors 68030

    cleanup

    Joined:
    Jun 26, 2005
    Location:
    Toronto
    #4
    Never mind, I found the problem. It's the bloody fluorescent lamp on my desk. When it's on, the transformer inside it interferes with the circuit and i get massive feedback through the speakers.

    At first I thought it might've been my printer so I unplugged it. In the process of unplugging the printer i accidentally touched the plug for the lamp and the buzzing disappeared for a fleeting second.

    Just my luck. :)

    Now I can record. Bloody finally.
     
  5. bigboy99 macrumors 6502

    Joined:
    Nov 12, 2005
    Location:
    Deep in the Heart of Tejas
    #5
    Re-routing the speakers and/or cables away from the lamp may help. This type of problem is fairly common as most consumer devices are not adequately shielded against RF (radio frequencey) interference.

    Happy recording.
     

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