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Thread: EV RE-20 Picking UP Buzz From Computer Monitor?

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    EV RE-20 Picking UP Buzz From Computer Monitor?

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    Can someone explain why this might be happening? I've got a desk boom stand whose base is close to an old cathode ray tube type computer monitor. the mic itself extends pretty far away from the monitor.

    Anyway, I noticed that there was an electrical buzz in the audio recording with the RE-20. I tried turning off the old monitor - luckily I have 2, the 2nd of which is a modern flat screen type. And behold, the buzzing stopped.

    It seems some sort of induction or magnetic interference is causing this buzz. Strangely though, this never happened with my LDCs.

    What is it about a dynamic like the RE-20 that would make it more susceptible to noise interference like this?

    Thanks!

    Ryan

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    Hi Ryan,
    Do you have a multimeter?
    I think it would be normal for any microphone to pick up buzz/hum in close proximity to an old CRT screen, or any mains transformer really,
    but if it's really over the top maybe the chassis of the microphone isn't making contact to the ground pin?

    I can't remember what the setup is in the re20, but it would be worth a check.
    ---------- Steenaudio Website ----------

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    Quote Originally Posted by Steenamaroo View Post
    Hi Ryan,
    Do you have a multimeter?
    I think it would be normal for any microphone to pick up buzz/hum in close proximity to an old CRT screen, or any mains transformer really,
    but if it's really over the top maybe the chassis of the microphone isn't making contact to the ground pin?

    I can't remember what the setup is in the re20, but it would be worth a check.
    Thanks. I do have a multimeter. But I don't know what I should do with it in this case :-P. Can you give me a clue on that?

    Cheers!

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    CRT displays used "scan coils" saddles of many turns of wire on the neck of the "tube". Through these ran the scan deflection currents of an amp or so of a near sawtooth (aka nasty!) waveform.

    The vertical deflection current would be 50 or 60Hz (bit higher these days). A dynamic mic is a coil of wire! Ideally suited to pickup the radiated magnetic field of the scan current. The mic also has a transformer in it and that does much the same. #

    Capacitor mics are mostly transformerless these days and since the mic element itself does NOT work by electromagnetic induction they are largely immune. Even those capacitor mics with an output traff probably use a "potted toroid" and they are resistant to stray fields.

    Dave.

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    There you go ^. Sometimes I know what, and he always knows why.

    You should have continuity between pin one and either grub screw; The one holding the 3pin in place, or the one in the headbasket.
    I doubt there's a problem, though. They just pick that stuff up pretty well.
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    Every thought about buying a new computer monitor? Several times I get brought files from home studios to mix and the single coil guitar pickup track has a buzz from the old style monitor.

    Alan.

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    Quote Originally Posted by witzendoz View Post
    Every thought about buying a new computer monitor? Several times I get brought files from home studios to mix and the single coil guitar pickup track has a buzz from the old style monitor.

    Alan.
    Yo!! You can pickup a basic jobbie at a charity shop for 15-20. I got a cracking 22" wide screen FSTV for 25 from the Scope shop (VGA and HDMI).

    Dave.

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    Quote Originally Posted by ecc83 View Post
    CRT displays used "scan coils" saddles of many turns of wire on the neck of the "tube". Through these ran the scan deflection currents of an amp or so of a near sawtooth (aka nasty!) waveform.

    The vertical deflection current would be 50 or 60Hz (bit higher these days). A dynamic mic is a coil of wire! Ideally suited to pickup the radiated magnetic field of the scan current. The mic also has a transformer in it and that does much the same. #

    Capacitor mics are mostly transformerless these days and since the mic element itself does NOT work by electromagnetic induction they are largely immune. Even those capacitor mics with an output traff probably use a "potted toroid" and they are resistant to stray fields.

    Dave.
    Aha! got it, Dave. Traces of my EE classes from college are seeping back in :-P. thanks so much for that explanation!

    R

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