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  • Phantom Power Effect On Dynamic Mics

    Hey I have a question:

    I read somewhere that if you are using a mixer that has phantom power on and off and it applies it globally that this could hurt the sound quality of some microphones that don't use phantom power. Is this true or myth?


    My female vocalist uses a phantom powered mic and right now my mixer has only phantom power on and off, no ability to put it into only select channels. Additionally, I am looking to order the Mackie DL1608, but it also only has phantom power applied globally or off.

    So before I tell my female vocalist that she has to leave her phantom powered mic home, I want to see if this is an actual issue or if it isn't going to cause any problems.


  • #2

    I just posted this over on the Behringer forum in response to someone saying:

    phantom power doesn't affect your dynamic mic's since the +40V travels on pin 3 of the XLR thats not used on Dynamic mic

    It hasn't shown up yet - dunno why I'm still on moderation after posting a few times .

    "Incorrect, phantom +48V is on both pins 2 and 3, which are BOTH used by dynamic mics. The 48V is relative to pin 1 which is ground. Dynamic mics should have the element (and transformer, if present) floating so that no current flows from pins 2 and 3 even though they are at +48V referenced to ground. You will still get a BIG pop if you disconnect the mic while "live" and if your cables and connections aren't perfect you will get crackling as someone said earlier . My solution on the DL1608 is to not use condenser mics and only use passive DI's"


    "We Have Met the Enemy and He is Us" - Walt Kelly​

    Comment


    • Mfk0815
      Mfk0815 commented
      Editing a comment
      I have an external phantom power device for four mics just for the case I have to work with such mixers.

    • OneEng
      OneEng commented
      Editing a comment

      RoadRanger wrote:

      I just posted this over on the Behringer forum in response to someone saying:

      phantom power doesn't affect your dynamic mic's since the +40V travels on pin 3 of the XLR thats not used on Dynamic mic

      It hasn't shown up yet - dunno why I'm still on moderation after posting a few times .

      "Incorrect, phantom +48V is on both pins 2 and 3, which are BOTH used by dynamic mics. The 48V is relative to pin 1 which is ground. Dynamic mics should have the element (and transformer, if present) floating so that no current flows from pins 2 and 3 even though they are at +48V referenced to ground. You will still get a BIG pop if you disconnect the mic while "live" and if your cables and connections aren't perfect you will get crackling as someone said earlier . My solution on the DL1608 is to not use condenser mics and only use passive DI's"


      I have had the same experience.

      If you have fantom power applied and disconnect the mic (even if it isn't using phantom power), you get a loud pop.


  • #3

    ChiroVette wrote:

    phantom power [...] could hurt the sound quality of some microphones that don't use phantom power.


    No.

    Condenser mics need phantom to power their internal circuitry. Dynamic mics do not care either way. As Andy explained, it's not a good idea to connect or disconnect any microphone while phantom power is applied and the system is live... you get rather loud pops coming through the mains. Just make sure the channels are muted!

    Andy, do dynamic mics have a bypass cap to filter the DC?

    Comment


    • fdew
      fdew commented
      Editing a comment
      Dynamic mics don,t need a DCBlocking cap because they don't see dc. The same voltage on pin 2 and 3 equals 0 volts across the microphone. Sort of like a bird sitting on a power line.

  • #4

    I often use smaller mixers with universal phantom on/off, and I've never had a problem using a mix of condensers and dynamic mics.

    The main consideration is just training yourself (and your band members) to never connect or disconnect a mic on a live channel so you don't get that loud POP through the system. Which should be a no-brainer, but people don't get it sometimes. It's just a good habit to get into, especially especially if you're not running the board yourself. 

    I'm also pretty careful about muting the mains and monitors when the band isn't actually playing, but that's just a backup for the occasional idjit who doesn't think and check whether the channel is live first, before connecting or disconnecting a microphone. There are many great-sounding condenser mics out there, and this isn't a reason to avoid using them (IMO).

    Comment


    • #5
      There is no connection between phantom power and pin 1 on a dynamic mic. The dc is common mode and no current can flow.

      Comment


      • ChiroVette
        ChiroVette commented
        Editing a comment

        Wow, you guys were definitely right about all the popping with phantom power engaged. It was a nightmare, every time I had to plug in or unplug any XLR cable the wholePA would pop. Looks like I am ordering my new gear this week...it's been WAY TOO LONG COMING, but I am finally able to take this particular plunge.

        Anyway, on the topic, it was horrendous, because I had not read this thread's responses and had no idea that the popping would happen with phantom power engaged. I basically finally had the presence of mind to turn the amp to the mains and monitors off every time I plugged of unplugged and XLR. But sometimes I would forget,


      • RoadRanger
        RoadRanger commented
        Editing a comment

        agedhorse wrote:
        There is no connection between phantom power and pin 1 on a dynamic mic. The dc is common mode and no current can flow.

        I've seen some years ago where pin 1 was the high impedance output from the internal matching transformer - think I've seen some where it was the center tap of the 600 ohm winding too?


    • #6
      You should always mute everything before connecting or disconnecting anything in your system anyway.

      Comment



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