phantom power abuse?

[osus]

hey gang,

i've read a lot of conflicting threads about how turning phantom power on and off at different points in the setup process can damage mics--both dynamic and condenser. i can't find a thread that's dedicated to the subject, so i thought i'd start one.

my process is to connect all mics with the power off the mixing board, then turn on the mixing board, then the phantom power, then the power amp stage if i'm using a PA. this way there aren't any audible pops. not sure if this is a bad idea, but i don't see how it could harm anything.

supplementally i wanted to present a problem and see if anyone could help me diagnose it: i have a sennheiser e865 which seems to be malfunctioning--occasionally the high end seems to fade in and out, and when it's faded out it sometimes snaps back in with a soft plosive. it sounds like a wide low-pass filter is on. i've tried different channels on the mixer and they all work the same. the only other mic i have to play with is an sm58, and it sounds like that all the time, so it's hard to tell--it could maybe be the mixer.

i always follow the power setup i described above, but sometimes when other band members set up they've turned on the mixer with phantom power on already and turned it all off at once. can this kind of thing damage a condenser? would it have this kind of effect?

to sum up: what's the best way to set up a live rig with phantom power, and what are the potential hazards of setting it up incorrectly?

thanks!

[Farview]

I have had the phantom power on my board turned on for 10 years. You will want to mute the channel when plugging and unplugging mics, but there is no reason to turn it off.

Disclaimer: Some DI's built into certain bass amps and keyboard amps will be damaged by phantom power as well as some very old and expensive ribbon mics. I would be shocked if 10 people on this forum have ever seen (in person) one of these old ribbon mics, so it isn't a big concern.

[osus]

thanks for the response. sounds like the problem i'm having is with the mic then... i guess i'll give sennheiser a buzz...

thanks!

[dementedchord]

while whether to plug/unplug condensers should not be a problem it can occasionaly... but it's admittedly rare... for instance fw1884's are known for eating pre's if you dont remove phantom first... so i dont think it would be a bad idea to get in the habit of shutting phantom down.... YMMV

[littledog]

The general rule of thumb is to connect or disconnect mics with the phantom power turned off. Once they are connected you can turn the phantom back on.

I try to do that, but on occasion I forget. I've never damaged a mic yet, but you might as well try and develop good habits. No sense tempting fate.

[SoundAsleep]

as far as PA goes...Power up amps last.....and when show is over amps are the first thing off

[TragikRemix]

yeah i dont sweat it too much.. but i always make sure all faders are down to ?. thats a better habit than worrying about phantom power on or off.

also, with live sound, bring the levels up slowly, one at a time, especially with large rigs, with multiple monitors and/or stacks. this way, if/when feedback hits, you know where it's coming from, and you don't kill anybody with the extremely loud noise that we all know too well.

[TragikRemix]

damn! i had the infinity sign, like on mixers, but it took it out and put a question mark...

[xstatic]

I would get in the habit of leaving phantom power off until it needs to be on. I would also mute channels when plugging or unplugging a mic. I would not however be turning the console on and off for this. Personally, to do it any other way seems a bit silly to me. It may not hurt anything, but why not do it right and play it safe all at the same time?

[cannabis]

interesting read:

http://recforums.prosoundweb.com/ind...sg/1521/0/0/0/

the last post is the most useful for me:

Klaus, èt al

Thanks you so much for this conversation. I for would be very interested in knowing about these matters.

As a user of of ribbon mics (and any other mic) for years I must admit that I have never had any problems with Phantom power..I have plugged, and unplugged mics with phantom power on many a time..Never had any failure of any mic, or never any damage done !!! I also build my own transformer based... all tube mic preamps..never really heard, or had any problems here either !!!

Id like to think that I try to take care of my equipment and mics, but I would really like to be told otherwise if thats the case

Gentlemen thanks for you time and willingness to share no B-S information.

Kind regards

Peter

[Innovations]

The only conditions that will cause phantom power to hurt a mic is if there is a short in the cable. Likely? No. Impossible? No.

[xstatic]

There is something to consider besides just hurting a mic... how about hurting the phantom power supply? A short in a cable cna do this, and sometimes even just the act of unplugging something in somewhat of an odd fashion can also do it.

[Brackish]

So, what's the truth here?
The need to turn off phantom
before plugging in a condenser is
basically an old wives tale?

[xstatic]

Is it a necessity? Probably not. Is it a good idea? Of course it is. There are several reasons why it MAY be a good idea to turn phantom power off before plugging and/or unplugging a mic. There are NO reasons why you should leave it on.

You should be able to find some sort of truth for yourself there

[Innovations]

Originally Posted by Brackish

So, what's the truth here?
The need to turn off phantom
before plugging in a condenser is
basically an old wives tale?

No, but the story that unless you turn it off you will certainly instantly destroy the microphone is something old sound engineers say to young sound engineers to play with their heads.

[cannabis]

Originally Posted by xstatic

There is something to consider besides just hurting a mic... how about hurting the phantom power supply? A short in a cable cna do this, and sometimes even just the act of unplugging something in somewhat of an odd fashion can also do it.

the phantom power specs

call for 6800 ohm resistors

in series with each leg

so a dead short will pull a maximum of

48v/6800ohms=7ma X2=14ma

from the supply

which shouldn't damage it

[xstatic]

"shouldn't" ? My whole point is why take the chance when it is so easy to just turn it off. I have seen many a phantom power fuse go in many a console. It never happens at a "good" time. Why did the fuse go? I can not say for certain. However, once again, why not just turn the phantom power off before making a connection or undoing one? It is so simple and then you avoid those chances. It just seems silly to even take a risk at all if it is so easy. I agree that in general it is safe, but sooner or later something may happen. The fact that it is so easy to contain that possibility just means that you deserve it if it does happen I guess.

[cannabis]

i agree it would seem to be best

to get in the habit of

turning off phantom

before connecting or disconnecting anything



i'm just sort of playing devil's advocate

to make the point

that the chance of damaging anything

by hot plugging is very remote

and shouldn't be agonized over

[Robert D]

I think that Bush has been seriously abusing his phantom power.

Best practice? Connect, then power up.

One thing to keep in mind is that some ribbons really don't like phantom power, so making a habit out of turning it off can make you think twice before turning it on with a ribbon plugged in.

[wilkee]

The BBC in the UK leave Phantom power turned on at all the outlets thoughout the building.

I try to remember to turn off before making or breaking a connection but often forget with the inevitable bang or crack through the P.A. but it has never caused any long term problems (apart from the laundry bill for my Boxers!!)

As xstatic says its probably wise too just in case.

Tony

[up-fiddler]

Originally Posted by Farview

I have had the phantom power on my board turned on for 10 years. You will want to mute the channel when plugging and unplugging mics, but there is no reason to turn it off.

Disclaimer: Some DI's built into certain bass amps and keyboard amps will be damaged by phantom power as well as some very old and expensive ribbon mics. I would be shocked if 10 people on this forum have ever seen (in person) one of these old ribbon mics, so it isn't a big concern.

My brand new Avantone ribbon mic states emphatically that phantom power must be OFF when using their mic. I turn mine off whenever it isn't needed. jmho

[Farview]

Originally Posted by up-fiddler

My brand new Avantone ribbon mic states emphatically that phantom power must be OFF when using their mic. I turn mine off whenever it isn't needed. jmho

Like I said, there are obvious exceptions.