Phantom power on dynamic mics

  • Thread starter Thread starter Morbidity
  • Start date Start date
Phantom power will not damage a dynamic mic.
 
Morbidity said:
I'm using this drum mics set: http://www.samsontech.com/products/productpage.cfm?prodID=1678

the overhead mics obviously need Phantom Power, but what about the rest of the set? will phantom power damage the rest of the set?

the mixer I'm using requires phantom power on either all of the channels or non of them :(
Click to expand...

Phantom Power will not damage a dynamic mic IF the cable is working properly AND you have a decent +48vdc circuit. If the mic cable shorts from either "-" or "+" to shield (gnd) then (depending on how good your +48vdc circuit is at current limiting) the capsule will conduct all the current with a +48v drop across it (acting as a resistor).

Some will go Poof!
Some will be demaged but still work. You will then open a new thread like:
"Help, my dynamic mic has low output and sounds bad"

A properly operating system of mic, cable, phantom power will be OK.

But that 1 time you get a bad cable...........Just test your cable everytime you use it if you care about your mics. A cable tester is far cheaper than replacing mics. The more expensive the mic, the cheaper it becomes.
 
MCI2424 said:
Phantom Power will not damage a dynamic mic IF the cable is working properly AND you have a decent +48vdc circuit. If the mic cable shorts from either "-" or "+" to shield (gnd) then (depending on how good your +48vdc circuit is at current limiting) the capsule will conduct all the current with a +48v drop across it (acting as a resistor).
Click to expand...

The number of coincidences that would have to occur here is rather extreme. The cable would have to be miswired; the +48V phantom power, contrary to international standards, would have to not be supplied across 6.8K resistors; the dynamic mic would have to be transformerless.

You don't need to worry about this.
 
mshilarious said:
"The number of coincidences that would have to occur here is rather extreme...."
You don't need to worry about this.
Click to expand...


Not too extreme. That is why I said IF..............AND

I have a few nice examples of some dynamics here in a box with:

1. Shorted transformer
1. Shorted capsule

Both from a Trident board. Someone (could'nt be me) had a shorted cable (not miswired). Twisting the cable for a while made one leg of the signal short to the shield. Some boards just throw the +48v out with no limiting at all.

It is unlikely today, as you posted, but something to know and check when plugging your mics into an unknown board or pre-amp.

Many of us are creatures of habit. One day you plug in a SM57 and nothing kills you, you just find a shorted cable and one day you finally get that RCA ribbon mic for too many $$$ and, absolutely. poof! gone.

Habits are good to make and good habits tend to save your butt.
 
main thing is don't EVER put +48v on a ribbon... or like above BYE BYE, I never feel good about having it on even on dynamics just knowing there's that 97% chance something could go wrong, but unless you have tons of routing options you have no choice
 
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