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Author Topic: Is it safe to unplug phantom powered mics when the phantom is on?  (Read 2460 times)

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Offline MJ

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Hi, all

Last night I taped a show in stXXlth situation with the MK4s > Nbox+ > M-10 combo and had to catch the train right after the show.  I was in such a hurry and completely forgot to turn Nbox off before unplugging MK4s.  I thought I heard some kind of statics (like the ones from radio) but I was puzzled and not sure where it came from.  Later on the train I noticed Nbox was still on and started worrying sick about what I really did this time. :facepalm:

Does it cause some damage to the mics when we unplug mics when the Nbox is on?

Any kind of info about this would be highly appreciated. :)

Koichi
<Main Rigs>
Schoeps MK4s>(Nbox Active cables)>Nbox+ or Nbox Platinum>Izzy (Split) Cables>Sony PCM-M10 or Sony PCM-D100

<Sub Rigs>
(1)DPA4061s>(terminated with 3.5 stereo mini)>Church Audio Pre>(3.5 stereo mini+Canare cable + 3.5 stereo mini)>Sony PCM-M10
(2)DSM-6S/L>(terminated with 3.5 stereo mini)> Sony PCM-M10

<IEM>
(1)scanner
 DJ-X2000
 IC-RX7
(2)receiver
Shure P10R
Sennheiser ek2000
(3)recorders
Marntz PMD706

Offline DSatz

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Re: Is it safe to unplug phantom powered mics when the phantom is on?
« Reply #1 on: March 16, 2016, 08:39:38 AM »
When you disconnect equipment, the main concern usually should be for anything that's still powered on (or carrying a charge from being on until a few moments ago). As an extreme example, think of a public address system that's turned on, and you disconnect the microphone. If the mike cable is still connected to the amplifier and speakers, this can produce a very loud "pop" or "bang" that could blow out speaker drivers and/or power amps. People standing near the speakers could spill their drinks on their partners, leading to nasty break-up scenes and eventually child custody battles and so on.

Disconnecting a condenser microphone capsule from its amplifier (the mike body, active cable, and/or outboard preamp such as your Nbox) is no threat to the capsule. But if the amplifier is on at the time, it will receive a voltage spike which it will try to amplify, and so on down the line. Most of the time that will be completely harmless, but there may be that one time out of 100, so it's not recommended.

I mean, at trade shows, I've seen Schoeps engineers unscrew the capsule from a microphone and replace it with another capsule, while the mike was powered up and connected to a preamp and headphones. They turned down the preamp gain temporarily, but the preamp's input circuit and the phantom powering were on the whole time. As I said, most of the time that will be completely harmless--but then again, those engineers had replacement mikes available if anything went wrong ... which they claimed it never did, but they still don't recommend that practice to customers.

--best regards
« Last Edit: March 16, 2016, 08:46:55 AM by DSatz »
music > microphones > a recorder of some sort

Offline Ronmac

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Re: Is it safe to unplug phantom powered mics when the phantom is on?
« Reply #2 on: March 16, 2016, 08:45:29 AM »
Best practice is to power down before you remove or add connections. Reality dictates otherwise, and using modern xlr connectors (ground pin on the male end is longer) helps to alleviate the problems.

Offline MJ

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Re: Is it safe to unplug phantom powered mics when the phantom is on?
« Reply #3 on: March 17, 2016, 03:21:16 AM »

Hi,DSatz,Ronmac,Jon
I really appreciate your input ;) ;) ;) ;) ;).  I was really worried about what really happened then.  Last night I tested mics and Nbox to see if I could hear some kind of noise.  Fortunately there seems to be nothing wrong with mics and Nbox.

As I said, most of the time that will be completely harmless--but then again, those engineers had replacement mikes available if anything went wrong ... which they claimed it never did, but they still don't recommend that practice to customers.

I will never ever unplug mics before turning Nbox off. :P :P :P  Thank you everyone.
I guess that I am a bit of nervous after I spent some much money on tickets for EC shows next month.

Koichi
<Main Rigs>
Schoeps MK4s>(Nbox Active cables)>Nbox+ or Nbox Platinum>Izzy (Split) Cables>Sony PCM-M10 or Sony PCM-D100

<Sub Rigs>
(1)DPA4061s>(terminated with 3.5 stereo mini)>Church Audio Pre>(3.5 stereo mini+Canare cable + 3.5 stereo mini)>Sony PCM-M10
(2)DSM-6S/L>(terminated with 3.5 stereo mini)> Sony PCM-M10

<IEM>
(1)scanner
 DJ-X2000
 IC-RX7
(2)receiver
Shure P10R
Sennheiser ek2000
(3)recorders
Marntz PMD706

Offline John Willett

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Re: Is it safe to unplug phantom powered mics when the phantom is on?
« Reply #4 on: March 21, 2016, 05:56:47 AM »
... using modern xlr connectors (ground pin on the male end is longer) helps to alleviate the problems.

Actually it's the female - sockets 2 and 3 are normally set back slightly so pin 1 mates first - the plug pins are all the same length.


Oh - and BBC studios normally had phantom power sent to all sockets at all times and mics were just plugged and unplugged as needed without any problems.
« Last Edit: March 21, 2016, 05:59:16 AM by John Willett »

 

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