Unplugged mic before turning phantom power off

phy61

New member
Today I bought my first phantom powered mic. It's a Se Voodoo VR2. I forgot and unplugged it before turning phantom power off. Is it a REALLY bad thing to do? Any of you did this before? I tried it again and it seems like it works but I'm still worried.
 
It probably didn't do any harm, and if everything sounds fine, then don't worry about it...but it could cause some damage, though rare, since the caps are fully charged with 48V and you might short to ground when hot unplugging....maybe to the preamp or you might hear a nasty pop in the monitors if they are on...etc.

Always turn it off...let it "drain" for about 10-15 seconds, and then unplug.
 
It IS possible even with an XLR, to have only two pins making momentary contact if you twist the plug a bit at that moment of disconnect rather than doing it perfectly even...and you get that voltage differential between them.

It's a minor point, I know, just like the potential damage...but it's best to follow the safest procedure.
 
In all my years I have lived with NEVER following the guidance on disconnecting and removing phantom power. All that happens is a nasty crack. In big PS situations connecting a mic with the fader up and unmuted and with phantom can make a sizeable BANG, but sometimes, looking at the 40m walk to FOH twice as nobody is around means I just cannot be bothered. I've never yet lost a speaker cone or HF driver, yet been yelled at plenty of time. The mics simply don't care. The voltage created by the two resistors across pins 2 and 3 simply appears or disappears. My opinion is that instant connection or ramped phantom application makes no difference whatsoever. I'm sure some mics have died over the years and are anecdotally mentioned as being killed by phantom application by plugging in the cable, but I suspect they would have died anyway, and the phantom power application is coincidence. Good practice says turning the fader down does the job in silence - the transient when the power connects is simply not heard.

I've never bothered with this common practice, and I have a few other 'must do' processes that I equally disregard (like turning power amps down before powering up) Never been an issue since I started in around 74/75. I know people violently disagree, but that's their choice. I simply do what is practical.

Any modern device that can be destroyed by 'incorrect' application was a dodgy device, and if they were so easy to damage, 3 year warranty on them would soon be removed!
 
Wes Dooley of AEA advises folks to make certain the phantom power is off before connecting/disconnecting dynamic mics as well because it is possible to compromise the transformer with the power still on.
 
I'm sure everyone has unplugged while phantom power is on at some point.....I do it probably once a week? As long as you unplug an XLR you are probably almost certain to be fine. Don't worry about it.

Just make sure phantom power is off next time. haha
 
The technical editor of Sound on Sound magazine worked for the BBC for many years and trained scores of sound production people.
He has mentioned several times that ALL BBC OB trucks and all their studios had permanent phantom power present. In all his years of swapping out microphones, including 4038s, he had never had a problem with either microphone or the supply.

The only real issue is the aformentioned noise but it is standard practice, instilled into new recruits, that "fader are always DOWN before anything is connected or dissed".

Dave.
 
If you look on other audio forums...on rare occasion people have posted that damage occurred when unplugging with phantom power on.
It doesn't mean it will happen to everyone, all the time...but how much do you value your better mics to not be concerned about it...?

I'm not seeing any net gain by NOT turning the phantom power off...other than maybe all of about 30 seconds total between power off & on if you're swapping mics.
It just always made more sense to adopt the safer trend, even if the risk was/is low....and even if it cost me those extra 30 seconds to do so.

It's like the speakers thing...everyone once in awhile I simply forget to follow the speakers on last /speakers off first procedure, accidentally, not intentionally...and I get that nasty crack in the speakers. I've not damaged them on those occasions, but it hasn't changed my following the more safe procedure...since I gain nothing by not following it. It's your gear...
 
There is no reason for a damage connecting or disconnecting a microphone with phantom power on. It's similar to connect or disconnect a bulb!
It's different if you short pin 2 or 3 to ground: in that case, the audio transformer inside the microphone (if it is not electronically balanced) can be magnetized, producing then distortion and loss of low frequencies. However, solution is simple: inserting and taking out the body part of the microphone in which is the transformer in a classical AC demagnetizer.
 
What is being overlooked is that it may not be the mic so much at risk...but your preamp input. Some are not as robust as others AFA protection circuitry.

This really isn't as much a case of the "shorting to ground" thing...though it can happen with TRS plugs very easily.
It's that when you "hot" unplug/plug into phantom power on, with mics that draw more considerable current...you will have large/fast voltage transient spikes at both ends of the cable. When power down/up with the switch, there is a more gradual dissipation, and no spikes.

Now again...if that is NOT a concern, or it's just too much trouble to turn off the phantom power..then proceed with your preferred method! :D
I find it amusing that anyone would argue in favor of a more risk approach...but I guess some folks like to throw caution to the wind. :)
 
I done a few numbers. The maximum dissipation in a mic's internal transformer from phantom power would be some 85mW but only if the DC resistance of the winding was a very serendipitous 6,800 Ohms. Higher or lower than 6K8 and the power is less.

To put that 85mW into context, a 32R headphone hit with 5V, +16dBu, a not unreasonable voltage, would dissipate some 780mW and headphone coils are pretty bloody wee! You do not however hear horror stories of cans getting burned out at all often?

Damage to the pre amp inputs: The pre amp designer must know that 48V will be present. He/she will also know that 48V is above the input limit for many devices and will therefore fit protection diodes. "Ah but, what if they cheap out and DON'T fit the diodes? Not going to happen since the pre production models would fail all over the shop. B.U.T. They CAN get away with not fitting protection to other inputs! Line inputs for example and yes, in such a case, the accidental application of spook juice could certainly destroy the input IC (there will still be no smoke or twisted metal. 85 THOUSANDTH of a watt remember?)

So, IMHO microphones and their pre amps are expected to meet and part with phantom powr and 't'appen and faults occur but if either suffers as a result that is shit kit*.

Now I freely admiit I do not have the vast experience of many forum members of studios and their doings. I only have my own electronics knowledge but I really think the risks to mics and preamps is very low indeed. Moreover, if a huge corporation like the BBC do not see fit to switch 48V and plaster warnings on the kit I think they know there to be no risk worth speaking of (I just wonder how 'king many mic XLR outlets exist in all the BBC studios and OB vans?)

Of course, turn off phantom power before connecting or disconnecting a microphone but if you forget, don't worry. VERY unlikely to cause any damage to anything.

So, if I was given a £3000 vintage ribbon mic would I let it take its chances? Of course not! In fact I would almost certainly build a capacitor isolator box and attach it to a dedicated mic stand and Superglue the XLRs in!

*I hold much the same view regarding 'power conditioners'. My view is that equipment should be designed to work to specification at mains voltage extremes, + and - 10% here and have reasonable internal filtering against RF and spikes. I do however understand that our colonial friends do not enjoy the same quality of mains power that we do?

Dave
 
Do it over and over again. Day in day out. For months. You won't hurt the thing unless it's already broken.
 
Of course, turn off phantom power before connecting or disconnecting a microphone but if you forget, don't worry. VERY unlikely to cause any damage to anything.

This is the thing I'm saying...and my approach.

I've done it too...pulled the mic and forgot it was still powered...and that nice "crack" in the speakers or the seeing the meters getting pinned for a moment is what made me realize what I've done. :eek:
Nothing was damaged...BUT...there are people who have clearly stated on audio forums that they HAVE gotten damage to mics or inputs. Without getting into their specific cases and reasons why they had damage when most people won't suffer it...is irrelevant, and I don't think they were lying about it...so the point is there is a "possibility"...not a "probability".

So with that in mind...people can do what they think is best. ;)
 
The only mics that I have ever had to die were a pair of CAD 411 dynamics. I think they are sensitive to the phantom 48V. There's no other reason that both died (at different times but under similar circumstances). Luckily I found a couple on sale for about $20 each, so they were easily replaced. I kind of like them on guitar cabs, not unlike my Senn 835s. They also give snares a little more snap than a 57 without sounding like a condenser.
 
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