Phantom Power to XLR cable question- (no Tele content)

Discussion in 'Bad Dog Cafe' started by chris m., Sep 1, 2004.

  1. chris m.

    chris m. Poster Extraordinaire

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    Gotliver and I have a question regarding phantom power. The Boss BR-1600CD has eight XLR inputs, with a phantom power option. However, when you turn phantom power on, it goes to all eight inputs- it's all or nothing. We were wondering a) would plugging a dynamic mic like an SM57 into a phantom powered input damage the SM57 or affect the recording; and b) if it would cause a problem, which pins on the XLR jack are involved with sending phantom power? Couldn't we just clip those pins off of an XLR cable in order to stop phantom power from going to a dynamic mic?
     
  2. soma5

    soma5 Tele-Holic

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    Chris,

    There are very few mics that are adversely affected by phantom power. Most new mics, your SM57 included, are not affected. Reputedly there are some ribbon mics that don't like phantom power but these are quite rare and expensive. So for almost all mics, they either use phantom power or ignore it. The reason manufacturers can get away with turning phantom power on to all mic inputs is just what I said above. Typically, phantom power is applied to XLR inputs, not 1/4" balanced inputs.

    As a precaution, be sure to apply phantom power AFTER the mics are already plugged in. I also turn it off before unplugging the mics, whether I need to or not.
     
  3. Robin Nahum

    Robin Nahum Friend of Leo's

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    And don't clip any pins off!

    All three conductors in a mike cable are needed to transmit the audio signal as well as power i.e. they double up in function.

    Mike cables are designed to be noiseless over long runs and use a similar principle to humbucking pickups. 2 and 3 (if I recall correctly) carry signal but are 180 degrees out of phase. At the mixer, one signal is inverted and then the two signals are combined and any spurious noise is cancelled.

    Pin 1 (the shield) is the earth.

    RN
     
  4. Flipped Mustang

    Flipped Mustang Tele-Holic

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    Yep, phantom power should not hurt or otherwise effect your other mics. When I got my Neotek console, the PP was turned on all the time. I rigged a swtich to turn it off when I didn't need it just for the heck of it.
    Rich
     
  5. gottliver

    gottliver Tele-Meister

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    now thats. . . .

    interesting and good news.
    I'm using an Audio Technica at3035 for recording my 0015 but I wanna add a dynamic (sm57) and record in stereo. So I can do it w/out FRYING the mic, excellent!
     
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