phantom powering non-phantom mics

[karambos2]

what happens if you connect a non-phantom powered mic like a Sennheiser 421 to a mixing desk feeding phantom power to it? Will it break?

[crazydoc]

Originally posted by karambos2
Will it break?

Short answer - no.
Read here and download the doc on phantom power, or do a search of this board.

[joro]

Originally posted by crazydoc
Short answer - no.

If it's a ribbon mic....phantom power will fuck it up....

or so I have read here abouts....

[Gidge]

http://homerecording.com/bbs/showthr...damage+dynamic

[crazydoc]

From the faq:

Bruce Bartlett
Will phantom power damage dynamic or ribbon mics?

When you switch on phantom power in some mixers, phantom is applied to all the mic inputs at once. What will happen if you plug a dynamic or ribbon mic into one of those inputs? Will it be damaged by the phantom powering?

Not if the mic has a balanced output, and is wired correctly. Even if the mic is a dynamic or ribbon type, phantom will not hurt the mic.

Phantom powering applies a positive voltage to pins 2 and 3 in the mic, and the ground of the phantom supply is connected to pin 1. In a condenser mic, pins 2 and 3 are wired to the circuitry inside the mic. Phantom current entering pins 2 and 3 goes through the mic circuit, then exits out pin 1 and returns to the supply ground.

In a dynamic mic or ribbon mic, pins 2 and 3 are wired to the mic?s voice coil or ribbon. Normally, the coil or ribbon is floating from the pin 1 ground. So the circuit loop to and from the phantom supply is incomplete. No current can flow through the mic?s voice coil or ribbon if you apply phantom power. Result: no damage.

On the other hand, if one end of the voice coil or ribbon is accidentally shorted to ground inside the mic, several milliamps of current from the phantom supply will flow through the voice coil or ribbon back to the ground of the supply. This current can deform the ribbon or immobilize the mic diaphragm.

In short, if the mic has a balanced output in which the voice coil or ribbon is NOT connected to mic ground, phantom will not damage the mic. If the mic has an unbalanced output because the voice coil or ribbon IS shorted to mic ground, phantom could damage the mic.

Hope this helps...

Bruce Bartlett
Mic engineer


Lambo
Following is a response from Beyerdynamic regarding ribbon mics and their inadvertent exposure to phantom power. The question: Phantom power damages ribbon mics, fact or myth?

James,

The Ribbon-Microphone myth is just that... a myth.

In Dynamic and Ribbon Microphones, pin 1 is wired to chassis ground. In
other words, the phantom power is dead-ended at the base of the microphone,
and will not reach the ribbon (or the dynamic's diaphragm).

Please be careful, though. If the microphone has been re-wired, post
factory, you may run into a problem: if someone decided to un-do the
grounding of pin 1 you can damage the diaphragm or ribbon.

Alexis Kurtz
_____________________
Alexis D. Kurtz
Applications Engineer
beyerdynamic))))North America
alexis@beyerdynamic.com www.beyerdynamic.com





drstaw
I don't own any ribbon mics, but I'd like to, having heard great things about their sound.
But I didn't start this "Myth" about the phantom power hazard.
Here's a quote from the Coles 4038 Ribbon Mic users manual:

NEVER PLUG THE 4038 INTO PHANTOM or "T" POWERED MIC INPUTS.
"T" Power will instantly destroy a ribbon and also can hurt a dynamic mic. Phantom power can do the same if you have a bad mic cable. It is best to play it safe by turning off the mic powering and wait a minute. After this it is safe to plug in your ribbon mic. This will allow both of the mic preamps' input capacitors to discharge fully after you turn powering off.

My conclusions are these:

1) Phantom power will not damage modern recording microphones (including ribbons and dynamics) that are factory wired and are connected with a properly wired cable.

2) Hot plugging (plugging the mic in or out with the phantom power on) probably won?t hurt the mic, though opinion is divided. If you have a mic you are very fond of or you can?t afford to replace, it would probably be prudent to switch the phantom power off for several seconds before plugging in or pulling out the mic.

[cominginsecond]

I think the whole "phantom power can cause damage to a dynamic or ribbon mic" thing is the most overblown phenomenon in pro audio today, except maybe the whole idea that digital recording is "cold."

I would invite anyone who's dynamic or ribbon mic has been damaged by phantom power to tell us their experience. I doubt we'll find anyone.

[ekotysh]

I just called GuitarCenter and they said not to plug in dynamic non-phantom mic into the board with phantom power, they said it might damage it. Even though I told them it's Shure sm57 mic, which I believe has balanced output

-Eduard Kotysh

[boingoman]

Originally Posted by ekotysh

I just called GuitarCenter and they said not to plug in dynamic non-phantom mic into the board with phantom power, they said it might damage it. Even though I told them it's Shure sm57 mic, which I believe has balanced output

-Eduard Kotysh

Whoever you spoke with at GC is wrong.

[tourettes5139]

Originally Posted by ekotysh

I just called GuitarCenter and they said not to plug in dynamic non-phantom mic into the board with phantom power, they said it might damage it. Even though I told them it's Shure sm57 mic, which I believe has balanced output

-Eduard Kotysh

Do you realize who you talked to??? GUITAR CENTER!!! 99% of those people there are complete idiots.