reshp1
New member
acorec said:
That still doesn't sound right, if your ground pin 3 isn't connected first, the 48V would bias your microphone ground up to the same potential, resulting in no charge across the capsule (or any other component).
That still doesn't sound right, if your ground pin 3 isn't connected first, the 48V would bias your microphone ground up to the same potential, resulting in no charge across the capsule (or any other component).
A
acorec
Banned
reshp1 said:
The worst possible scenario is when a mic lead is connected to a mic while phantom power is on. The cable is effectively a capacitor, and the sudden discharge of the cable and coupling caps can create a high current through the zeners, which must be capable of withstanding the surge without failure.
Now, these zeners (as most zeners tend to be) have a rather large tolerence and can allow quite a jump in current. The end product is that you stress your mic everytime you plug it in, or pull it out just a little. Like ESD discharge, the unit does not fail the 1st, 2nd, or who knows? But, sooner or later you could be the owner of a useless mic costing $100-2000.
Why risk it? Any pro would kill you if you ever did this in their studio.
And, I am quite aware that old consoles did not have phantom power switches and old engineers did this for years............
But.............
Old engineers blew up mics and everything is invented to solve a problem.
Guess what? Phantom Power switches on every channel were introduced.
Why?
reshp1
New member
acorec said:
Where does the current come from? the cable has very little capacitance, 50pF/feet on average, not enough to store large charges (not to mention it also has inductance that limits sudden current surges). The mic zener is current limited by a resistor in the kilaOhm range, same on the phantom supply side. Which coupling capacitors (and zeners) are you refering to?
A
acorec
Banned
reshp1 said:
OK. It is a great idea to plug and unplug with phantom power on.
I highly recommend it always.