Topic: Stupid question.. Disconnecting mics while phantom power is on?

[rodeen]

Last night I accidentally unhooked my mic while they were still getting phantom power from my HD-P2.  Is that a bad thing?  Can I damage the mics and/or the P2 by doing something like that?

 

[eric.B]

hmmmmmmmmmm.. good question.. I know the reverse is bad (plugging them in while phantom is on), but unplugging them while they are powered is something different.. maybe?.  My first guess is that it's not a problem, but I could be wrong. 

[sygdwm]

saturday night i switched caps on my 460's during set breaks w/ phantom power on accidentally. but nothing bad happened that i can tell.

[boojum]

What would the difference to the mic be between plugging them and and turning on the power and plugging them into a line where the power is already on?     

[twatts (pants are so over-rated...)]

Its just not a good idea, in my mind, to plug or unplug your mics with the 48v turned on.  But I also think that doing it once in a bluemoon isn't going to harm your mics. 

I use a HD-P2.  I plug in my mics and then turn on the unit's power.  It has switches for 48v which I leave turned on.  Once I have my mics flying, I give them power as I turn on the unit, but I don't think this is a good idea either...

I really liked the fact that the UA5 had a 48v "pad" - it turned off automatically every time so there was no chance of damaging your mics...

T

[ghellquist]

Phantom power was designed to support this. According to what people has written in other forums, the BBC used to have phantom on permanently in their wall boxes in the studios so no choice there. So it should not be a problem connection or disconnection with phantom on, I have done it often enough.

Still, if possible avoid it.

Gunnar

[boojum]

Phantom power was designed to support this. According to what people has written in other forums, the BBC used to have phantom on permanently in their wall boxes in the studios so no choice there. So it should not be a problem connection or disconnection with phantom on, I have done it often enough.

Still, if possible avoid it.

Gunnar

Gunnar - You have me confused.  You say the standard was designed for hot plugging and unplugging but to not do it.  Whazzup???

[ghellquist]

Gunnar - You have me confused.  You say the standard was designed for hot plugging and unplugging but to not do it.  Whazzup???

In my world it is simply a good habit. Sooner or later I end up in a situation where it makes a difference. Such as pulling the mic with the headphone volume really high (ouch). Or getting a second chance to find out that the cable not goes to a mic but instead to the output of some other equipment that might not like 48V up the back. Or by mistake connecting a band mic to a phantom powered output. (All band mics I have seen can take phantom with correct cables and contacts, but exactly when you make the connection the contact is not perfect). Just maybe it is a bit of belt and braces.

Gunnar

[guysonic]

A quick clean disconnection while powered should not cause any problem with mic or deck, but connection while hot may not bode well with some mics where surge damage is unlikely, but far more a possibility.

[boojum]

With an SD 7xx you are safe.  I wrote the company - what a concept - and was told it makes no difference.  They have a diode in the circuit to keep harm from happening.  If you are running other gear, check with the manufacturer.  They will be far better than the "I guess" or "I think" that you might get elsewhere.

Cheers   

[J.T.L]

When I was getting an Oade pre fixed, Doug asked if the mics were ever connected or disconnected with it powered. I said no but asked why and he mentioned (if I remember correctly) plugging mics into a pre w/ phantom on can damage mic capsules and disconnecting w/ phantom on can cause capacitors in the pre to leak and die.

[boojum]

OK, I wrote SD and they said it is OK.  Now I will write my mic mfr and see what they say. 

L8R

[Dutchman1101]

saturday night i switched caps on my 460's during set breaks w/ phantom power on accidentally. but nothing bad happened that i can tell.

Did the same thing last night with the Neumanns I dont think anything happened though. I've done the same thing in the past with other mics with no problems. I would rather not have done it but I dont think a once in a while thing will hurt them.

Harrison

[boojum]

I got this from Schoeps.  I doubt that they are different from other mic manufacturers.  Also, Schoeps mentions mixing consoles.  I doubt knowledge of this would be confined only to mixing consoles.  I have had both SD and Schoeps say it is OK.  You can say what you want, I am betting on these guys.  If you have doubts about your hardware, why not write the manufacturers instead of gassing about it?  Unless you just want to gas about it rather than get a reliable valid answer.

"Hello Robert,

as long as the phantom power is within specifications (i.e. 48V ± 10% @ 6.8kOhms) it makes no difference for our microphones if  powering is on or off during plugging.

With no microphone connected the input capacitors of the mixing console are charged to 48V. The very first moment of connecting a microphone may be similiar to a short circuit as inside the microphone there are capacitors who are discharged to zero. The designers of both microphone and mixing console know this effect and will integrate some means of protection like zener diodes or resistors or chokes. The zener diodes will prevent the voltage getting too high for certain components. The resistors will prevent a too high current and the chokes reduce the shoulder of the peak.

A damage may occurr if someone "modifies" his power supply or creates one of his own ignoring such protection rules. In such cases it is highly recommended to plug and unplug the microphone only with the powering switched off. We know users who drive their microphones with up to 70V why ever. For our microphones this will lead to no advantage at all but to a very high risk to damage them.

My personal experience with plugging and unplugging SCHOEPS microphones since more than 20 years that I am working here:
I never switch off the supply and I never had any defect by doing this.

With kind regards


Bernhard Vollmer

Head of Quality Control & Customer Care
Phone +49-721-9432021
Mail vollmer@schoeps.de
_________________________________________________________

SCHOEPS Mikrofone GmbH, Spitalstr. 20, DE 76227 Karlsruhe
Amtsgericht Mannheim, HRB Nr. 102442, Geschäftsführer: Ulrich Schoeps"

[TNJazz]

Why take a chance?

Don't plug your mics in with phantom on if you can help it.