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Harmful to leave phantom power on through power cycling?


dschreiberjr

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I have a bit of a stupid question for you all. I have Sennheiser MKH8000 series mics feeding a Mix Pre-D. Assuming I always use mics which require phantom power, is it harmful to any piece of equipment to always leave phantom power on when shutting down or powering up the Mix Pre-D? Has anyone ever experienced any issues or damage as a result of not cycling phantom power appropriately? I have been leaving the phantom power on through shutting down and powering up the mixer simply for the sake of convenience. I'm curious what your thoughts are on best practices regarding this.

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I would seriously doubt that power cycling with Phantom Power switched on will cause any problems. Phantom Power is relatively safe except maybe in situations where you are using an input (with Phantom Power switched on) to monitor a return from a Camera or other device via it's Earphone/Headphone output.

 

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In professional recording studios one never leaves phantom power engaged while power cycling or plugging/unplugging mics. Why one would do it in the field makes little sense to me, coming from that background and philosophy. I even power down my wireless when plugging or unplugging lavs. 

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I've been using P48 ever since I moved away from 12T and I have never had an issue with anything related to phantom power.  I routinely power gear up and down, plug and unplug mics, hot swap heads.  My boss always shuts everything down.  Not me.  Just my $.02.

D.

 

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I think it's a good idea to get in the habit of turning phantom off before you plug and unplug mics, but if it doesn't happen I wouldn't worry too much about it. Modern mics are designed so that they should be fine if everything is within spec. It's just if something malfunctions that there would be an issue (or with some vintage mics). 

There's a bunch of gear used in professional recording studios that has phantom power on all the time, like some of the Neve consoles, so in those cases you wouldn't even have the option. 

-Mike

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34 minutes ago, Mobilemike said:

I think it's a good idea to get in the habit of turning phantom off before you plug and unplug mics, but if it doesn't happen I wouldn't worry too much about it. Modern mics are designed so that they should be fine if everything is within spec. It's just if something malfunctions that there would be an issue (or with some vintage mics). 

There's a bunch of gear used in professional recording studios that has phantom power on all the time, like some of the Neve consoles, so in those cases you wouldn't even have the option. 

-Mike

I'd like to hear of how it can hurt gear if the phantom power ISN'T turned off.  I've never heard of a case where it has.  Why should I get in the habit if it's an old wife's tell?  

 

I use to work for a mixer that wouldn't let me unplug the boom until the fader was down - back in the days of hardline booms.  He was never at the board and I'd be standed on set needing to get back to the follow cart to do something important.  It would piss me off to no end. 

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4 hours ago, Mirror said:

I'd like to hear of how it can hurt gear if the phantom power ISN'T turned off.  I've never heard of a case where it has.  Why should I get in the habit if it's an old wife's tell?  

Like I said, really the only way that phantom power can damage modern audio equipment is if some of the equipment is faulty. Of course as we all know, any piece of equipment can fail at the most inopportune moments, which is why I still think it's a good habit to get into - just to remove one more possible source of further damage. 

Phantom power works by sending the same voltage down both the + and - lines of a balanced cable. This makes it invisible to equipment that doesn't need it, as it will just cancel out. Problems can occur though when a cable gets damaged, or is wired incorrectly, or something if that sort, because it's possible then that suddenly that voltage is only traveling through one side of the cable. It's also possible (though rare and unlikely) that of a cable is poorly made, it will unplug unevenly, causing one of the pins to lose contact an instant before the other, and briefly sending voltage down only one line. This sort of thing can damage even mics designed to use phantom power. 

Again, all this is rare enough not to stress over, but then again, why risk it if you have the choice?

-Mike

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7 hours ago, Mirror said:

I'd like to hear of how it can hurt gear if the phantom power ISN'T turned off.  I've never heard of a case where it has.  Why should I get in the habit if it's an old wife's tell?  

 

I use to work for a mixer that wouldn't let me unplug the boom until the fader was down - back in the days of hardline booms.  He was never at the board and I'd be standed on set needing to get back to the follow cart to do something important.  It would piss me off to no end. 

I have already explained one situation where having Phantom Power switched on can damage equipment.......... ignore it at your own peril !!!

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It is true that the only p48 situation I watch out for is video cameras having it on their inputs--there have been issues with some mixers re: this over the years.  Turning the camera p48 off should be part of the drill when switching it to line level, setting levels, turning off "wind filters", AGC and making sure that input #1 is only going to channel #1 and not to both channels etc..

 

 

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There are certainly occasions where phantom power can damage equipment, though probably not mics.

I have two Lectro SRa's for example, which were both damaged by phantom power, when I re-patched things and didn't remember to switch off phantom power. Or rather, one of them was damaged by a friend, but that's a different story. The german distributor could repair this easily, but also costly, so even though I would guess that newer receivers are better protected, it is nonetheless good practice to switch phantom power off as SOP

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If the equipment or cable is faulty (as mentioned above) then I can see no difference in leaving P48 on while you connect cables OR turning it on AFTER you connect cables. The faulty equipment will still react the same way in either case.

Not sure if that is a reply to my earlier post, but the receivers in question were not faulty, or rather, they were faulty on a design level.

Of course the idea would be to not turn on phantom power when equipment is connected which doesn't need it.

But as such, your statement is correct, of course

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