Phantom power to condensor and dynamic?

M

Mip

New member
I've got an MBox2 on order, and have just received my SM58 and SM86. I noticed that there isn't a separate phantom power switch for each preamp in the MBox2, so is it going to be a problem using both of these mics at the same time - i've heard that it's ok to send phantom power to a dynamic mic as long as the cable is balanced?
Also got my Wharfedale Diamond Active 8.2's - i'm just itching to plug all this gear in and get recording.
Anyway, any help is appreciated.
 
I'm no expert but I read somewhere, I think it was here, where it wont hurt the dynamic to have phantom power on. You might try the search feature.

Also, I run both dynamics and condensers when my band plays live and it doesnt hurt them. There's only one switch for phantom power. I think mackie, which is the board we use, would put a switch for each channel if it mattered.

Marc
 
Your dynamic will be fine. Phantom power through a ribbon mic is a big no-no, unless it is one of the ones designed to take phantom, but that is a relative rarity.
 
There's nowhere for the power to go in a dynamic mic, so no problems having the phantom switch on.

Though I have heard of people getting electric shocks on their lips when using some mics live - could this be because the mic isn't properly earthed and phantom power is on?

Dags
 
Dags said:
There's nowhere for the power to go in a dynamic mic, so no problems having the phantom switch on.

Though I have heard of people getting electric shocks on their lips when using some mics live - could this be because the mic isn't properly earthed and phantom power is on?

Dags
Click to expand...

No that's not because of phantom power. That is usually because of faulty wiring in the venue, or a grounding issue with the amp and the mic. Something like that.
 
So the solution would be to NOT EAT THE MICROPHONE!! :D

I had a guy talking to me on Sunday about a weird problem he was having where an SM58 would zap their lips and a Beta58 wouldn't?
Same cables, same desk...plug in SM58 [zap] replace with Beta58, fine, plug SM58 back in again [zap]
I had NO way of offering a solution to this mystery!
My only thought was that there might have been a dodgy earth plug in the SM58 in combination with some kind of faulty earthing in the cable.

"Curiouser and curiouser" said Alice.

Dags
 
Dags said:
So the solution would be to NOT EAT THE MICROPHONE!! :D


Dags
Click to expand...


Nope, that's not the answer. :D

I know a guy who had electricty zap him from almost 12" away, and it cut his upper lip open.

Thank the heavens for Wireless mic's and wireless guitar transmitters!



Tim
 
Dags said:
So the solution would be to NOT EAT THE MICROPHONE!! :D

I had a guy talking to me on Sunday about a weird problem he was having where an SM58 would zap their lips and a Beta58 wouldn't?
Same cables, same desk...plug in SM58 [zap] replace with Beta58, fine, plug SM58 back in again [zap]
I had NO way of offering a solution to this mystery!
My only thought was that there might have been a dodgy earth plug in the SM58 in combination with some kind of faulty earthing in the cable.

"Curiouser and curiouser" said Alice.

Dags
Click to expand...
The screen on the Beta might not be electricly connected to the mic the way a SM58 is. If it happens at all, it is a grounding issue in the venue. The PA has a much better ground than the guitar amp does (or the other way around) and when you touch the mic, the amp tries to ground itself to the PA through you. This is one of the reasons why you never pull the 3rd pin off of the plug. Situations like this can kill you.

BTW Phantom power is fine for dynamic mics.
 
Last edited:
soundchaser59 said:
Do you know how much voltage it takes to jump an air gap of 12 inches??
Click to expand...


Lots... I recall from an electrocution case I defended many years ago that an uninsulated 8,000 volt power distribution line (like what runs along your average road, top wire) will arc to ground over about 1/8 to 1/4 inch - max. In a heavily ionized atmosphere, such as just after a lightning strike, that might be a little longer distance - like another 1/8th of an inch. So in my case the poor guy's aluminum ladder actually did hit the power line ...

If it were otherwise, the distance between power line conductors would have to be increased and you'd have four foot (and not four inch) insulators on the power poles. That's also why transmission lines have such big towers - strength and safety. They carry lots of juice.

I try to avoid stray voltage problems by routing all my gear through one outlet and testing the outlet with a five dollar polarity tester. You can pick one up at the hardware store. Plug it in and you get "go / no go" lights. The only problem my band has ever had arose from oddball wiring where everything was plugged into different outlets and some idiot wired an outlet backwards - 30 years earlier. That can be seriously bad juju. And I wasn't there to yell at everyone... :cool:

BTW, dynamic mics are OK with phantom power. :cool:
 
soundchaser59 said:
Do you know how much voltage it takes to jump an air gap of 12 inches??
Click to expand...

I never had heard of it jumping that far either, but there were several people there who saw it happen - I didn't actually see it. I was outside loading in some gear (it happened during a soundcheck) and it happened right when I was coming in, I just saw him go flying backward and didn't know what was going on. It turned out nothing in the place was grounded - neither the PA nor his amp, and the dumbass didn't have any shoes on. The people who actually saw it said you could see it come from the mic to his mouth. He almost looked like he's had surgery for a harelip/cleft lip after it happened.

I've been thrown over 6 feet by the shock from a guitar, and I'm 6'2" and weigh 250 lbs, but that's not the same as electricty carrying through the air....that's "Tim being airborne", not electricity. :D



Tim
 
You must log in or register to reply here.
Back
Top