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    When to use phantom power?
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    Guys. I use basic Seinheiser wireless lavs and Audio technica boom mic with my hvx. Should I be using phantom power or not? Is there a good way to know when to use and when not to?
    Many thanks in advance.


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    Section Moderator Alex H.'s Avatar
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    Look at the specs of your mic. That will tell you.

    I fit's a condenser mic, it will need phantom (unless it has a battery compartment, in which case it probably uses either or). Condenser mics do not generate their own signal, and need a power supply to charge the diaphragm inside the mic capsule. This supply of electrical current cancels itself out after it hits the mic, hence the term "phantom power."

    If it's a dynamic mic, it does not need phantom. Dynamic mics create their own signals. Remember in grade school science classes when you learned about creating electricity with a metal coil and a magnet? Dynamic mics do that.

    Wireless lav systems do not need phantom.

    You didn't say what, specifically, your "boom" mic is. Is it a shotgun mic? Model number? CHacnes are, it takes phantom, but it will be helpful to know which mic it is.

    Please note that some devices may actually be damaged by phantom power. If you're using an external mixer, do not send it phantom power.
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    Thanks for your response. Not sure what my boom mic is. I'll find out. But I often use other boom and stick mics so I guess that is not as important. I think I have been using my wireless lav with p power on. Does it affect the sound recording when I do this? Also, if I use a mic that does require p power but I have the switch turned off, will I still be able to hear something? In other words, is it a good test to start with the p power switch on the camera set to off, and test the sound and then turn it on if I can't hear anything?


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    Section Moderator Alex H.'s Avatar
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    If a mic requires a power supply, and does not have said power, you will not get a signal.

    It is also good practice not to use phantom with any mic or device that does not require it. It probably won't cause problems with your wireless receiver, but it's just good practice to keep it off when you don't need it.
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    Thanks for your knowledge C2V.


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    If you have a typical Senn G2 or G3 wireless, they do not use phantom power. Some of the higher end Senn wireless units do supply phantom to the mic, but don't need it at the receiver.

    Grant


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    NEVER use phantom power unless the microphone requires it. It is often a very bad idea to feed phantom power to things that don't need it. Some microphones and other equipment can be damaged by phantom power. Furthermore turning on phantom power on a portable mixer, camcorder, recorder, etc. eats extra battery power and that is another good reason to leave it off unless you can't live without it.
    Recording audio without metering and monitoring is exactly like framing and focusing without looking at the viewfinder.


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    Quote Originally Posted by Richard Crowley View Post
    NEVER use phantom power unless the microphone requires it. It is often a very bad idea to feed phantom power to things that don't need it. Some microphones and other equipment can be damaged by phantom power.
    Unless you're using old ribbon mics, that's not an issue. Any properly wired, balanced mic / gear is completely unaffected by phantom power unless it's making use of it.

    Most small and many medium form-factor boards for live sound have only a single switch for phantom power that applies power to every mic channel of the board. You can have five or ten dynamics, a few condensers, wireless receivers, and a DI box or two all hooked up to a board with the phantom power turned on and there is exactly zero trouble.

    The only time phantom is a potential for trouble is when using older ribbon mics or trying to mate unbalanced gear to your balanced, phantom-powered inputs.

    Quote Originally Posted by Richard Crowley View Post
    Furthermore turning on phantom power on a portable mixer, camcorder, recorder, etc. eats extra battery power and that is another good reason to leave it off unless you can't live without it.
    Very true. In the situations we usually find ourselves in in the field, phantom can be a drain on battery life if you've got it on unnecessarily.


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    Quote Originally Posted by JordanBlock View Post
    The only time phantom is a potential for trouble is when using older ribbon mics or trying to mate unbalanced gear to your balanced, phantom-powered inputs.
    Or when feeding a mixer's XLR outputs to another XLR input with phantom activated. You can fry a field mixer by sending mic-level XLR out to a camera with phantom turned on.
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