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Phantom Power

Discussion in 'Sound, Music, and Intercom' started by Eboy87, Jun 30, 2009.

  1. Eboy87

    Eboy87 Well-Known Member

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    So I know they make stand-alone phantom power supplies for mics, but do they make the opposite? I'm looking into getting a Cascade Fat Head, but my concern is running into situations with a broken snake leaking phantom power onto all channels. I don't really want my ribbon mic becoming a speaker for a very short period of time. Do they make a phantom power blocking device?

    Or in this case, since I can order one with a transformer, do I not need to worry about phantom? Everyone I've spoken with (since I don't have first hand experience with ribbons) says ribbon + phantom = no more ribbon.

    Thoughts?
     
  2. mbenonis

    mbenonis Wireless Guy Administrator Premium Member

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    If there is a transformer between your microphone and the console, phantom power will be blocked. Short of adding a transformer, you could also put two capacitors in line (one on the + and one on the - leg), but a transformer would be a much nicer solution. You'll want a transformer with a 1:1 windings ratio so as not to change the impedance that the microphone sees.

    It's worth noting that GOOD transformers are fairly costly...expect to pay in the neighborhood of $100 for a Jensen transformer box. That said, if you are investing in a good ribbon microphone, this figure shouldn't make you blink too much.

    EDIT: Some links:
    http://www.jensen-transformers.com/ (Jensen Transformers; lots of good info here)
    http://www.radialeng.com/di-twiniso.htm (Dual-Channel Jensen-Xfmr-based isolator)
     
  3. museav

    museav CBMod CB Mods Departed Member

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  4. Eboy87

    Eboy87 Well-Known Member

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    Thanks Muse, somehow I missed that. And yes, they do have a transformer in them; I have the option to order the standard or the Lundahl. I should think the standard suits my needs just fine.
     
  5. FMEng

    FMEng Well-Known Member Fight Leukemia

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    Your premise is a little shaky. A broken snake isn't likely to "leak phantom power onto all channels." Maybe that'll happen if you squish it by driving a big truck over it, (flattening/shredding the cable) but otherwise the most common failure is simply an open wire on one pin of a channel.

    Phantom power is only a concern with some models of VINTAGE ribbon mics because they had a grounded center tap on the internal matching transformer. And then, it is only a concern while plugging things together. Basically, unless you are using a 40+ year old RCA, don't lose any sleep over it.
     

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