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Phantom power

Discussion in 'Sound, Music, and Intercom' started by chriskreidler, Mar 2, 2009.

  1. chriskreidler

    chriskreidler Member

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    Can phantom power hurt anything? I need it for some floor mics, but I also need to plug in a laptop to the mixer at the same time. Could phantom power hurt the laptop?
     
  2. Footer

    Footer Senior Team Senior Team Premium Member

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    No, you should be using Mic Level inputs for your floor mics and Line Level inputs (usually 1/4") for your laptop. Phantom power is not sent over line level connections. I run laptops and all that fun stuff off of consoles with global phantom power all the time without a hitch.
     
  3. museav

    museav CBMod CB Mods Departed Member

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    If you want to run the laptop into a mic input (or two inputs) get something like this, Whirlwind / Direct Boxes or this, Pro Co Sound |.
     
  4. rwhealey

    rwhealey Active Member

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    Some mixers do not have 1/4" line inputs, but only have an XLR with a pad, like our Soundcraft MH3.

    If you don't have line inputs, I would recommend the DI solution.
     
  5. avkid

    avkid Not a New User Fight Leukemia

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    You might want to look again.
    [​IMG]
     
  6. rwhealey

    rwhealey Active Member

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    The top connector is a 1/4" Direct Output

    The middle two are balanced insert send and balanced insert return. The return (if I am reading the schematic correctly) could be considered a "line in" but is after the high pass filter.

    The bottom is the XLR, while the "gain range switch" is the pad for line level sources.
     
    Last edited: Mar 3, 2009
  7. FMEng

    FMEng Well-Known Member Fight Leukemia

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    As others have said, phantom power applied to anything other than a microphone or direct box can cause problems.

    This is slightly off topic, but it is wise to avoid connecting vintage ribbon mics (think RCA 77) to anything with phantom applied. Those mics have a grounded center tap. When one connector pin makes before another, the current flowing can induce movement in the element and destroy the ribbon. If I have to use phantom around a ribbon mic, I make sure the connections are made before turning on the phantom supply.

    This is NOT a problem with any other type of mic, dynamic or otherwise.
     
  8. themuzicman

    themuzicman Well-Known Member

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    That iFace looks really great, the idea of having consumer to pro cables! Wish it wasn't so expensive, really love the idea.
    I'll stick with my $25 Behringer DI box and a patch cable for now. Anyone have any experience with the iFace, any reviews to be had?
     
  9. spiwak2005

    spiwak2005 Member

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    Also slightly off topic - I was always taught never to plug in or unplug anything with phantom power on. Is this not true? Is it ok to plug/unplug dynamics and/or condensors with phantom on?
     
  10. Dionysus

    Dionysus Well-Known Member

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    One of my sound teachers told me much the same thing, adding to wait for 5 minutes until phantom was totally gone. He said that patching/unpatching with phantom active on the channel could eventually damage the preamp/phantom circuits in the console.
    He said that it didn't necessarily happen but better to be safe than sorry.
    Didn't matter much, the consoles we used all had individual phantom for each channel or at least a set of channels. We only turned phantom on where it was needed.

    Not sure how much truth there is to it. I do know about electronic circuits from my schooling as an electrical apprentice, so I can say it is somewhat plausible.

    *shrugs* on smaller consoles I never bother to turn phantom off. If I turn it off, the next person comes crying to me that they can't get some of the microphones to work. lol.
     
  11. themuzicman

    themuzicman Well-Known Member

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    I was always told just to switch off phantom before unplugging.
    It would seem that waiting five minutes would be in the event a capacitor is on there, but I didn't know that there were even capacitors on a phantom circuit. Eh, whatever. Turning off the phantom, waiting the time it takes to unplug the line is good enough for me!
     
  12. museav

    museav CBMod CB Mods Departed Member

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    Plugging and unplugging devices into XLR connectors with the phantom on should not be a problem with a properly designed mixer, but the phantom power circuitry being properly designed is a bit of an assumption on some mixers. TRS connectors are another matter, you do want to turn off phantom there as you can short the connections while inserting and removing jacks.
     
  13. bhallerm

    bhallerm Member

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    Only thing you can really destroy with phantom are ribbon mics. (except the Royer R-122) Phantom will fry an ribbon mic instantly. And I've heard/been told similar things about hot plugging phantom. We used to be careful of that on the SSL and Trident boards. 5 minutes seems a bit excessive though. 30 secs to a minute sounds a little better.

    Brian
     
  14. FMEng

    FMEng Well-Known Member Fight Leukemia

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    In my 22 years of working professionally with microphones and consoles of all types, I have never turned the phantom off to connect or disconnect, except for two circumstances: One is when using a vintage ribbon mic, and the other is if the mic line goes through a telephone style patch panel and I am re-patching.
     
  15. waynehoskins

    waynehoskins Active Member

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    I've always hot-plugged with phantom with no problems. On the older consoles you didn't even have a Phantom On switch; it was just always there, everywhere. Mute, plug, done. This makes something like 15 years of that for me, and 15-20 years on top of that for the guys I learned from.

    The one thing I do, though, is make sure to mute when hitting the channel Phantom switch, to avoid the Big Pop.
     

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