02-08-2013 05:02 PM
I've got a very basic 2-input Presonus USB Audio Box. It's able to supply ghost power through both ports at once. There's just a single master switch for ghost power to both ports.
So my question is what happens if i have a Condensor Mic plugged into one port that needs the power and something like a dynamic mic or electric instrument plugged into the other, does the audiobox know to divert power to only one, or does that risk damaging the input that doesnt need the power?
02-08-2013 08:10 PM - edited 02-08-2013 08:20 PM
Dynamic microphone don't use phantom power, but it does not matter if phantom power is on or off when the dynamic microphone is symmetrical wired.
Condenser microphone are adjusted to a phantom power, powering the circuitry of the microphone, usually 48V 6,8 kΩ today
02-09-2013 12:28 AM
02-09-2013 08:06 PM
I love the interface. It's begining to become a bit limited as i take on larger projects, but for the stuff i do it's graet. I could probably never fully mic a drumset with it, but it gets the job done.
Thanks for the answers. But what happens if i have a condensor plugged into one slot and a guitar plugged directly into the other? Does ghost power hurt the guitar?
02-10-2013 04:36 AM
No, Phantom power is only supplied to mics that run on phantom power over a three conductor low impedance XLR cable. If you plug a guitar in you're running high impedance and the power isnt supplied to the cable.
Dynamic mics are wired so the power isnt connected to the mic so theres no issue with that.
As someone said before theres only a few vintage ribbon mics that had a different wiring scheme that could be damages by todays phnatom power. Its highly unlikely you will ever own one of those vintage mics. All other mics and all new ones are standardized so they either run on standard phantom power or they dont see the phantom power and cant be damaged.
The exception of course is if you use an external preamp or effects unit for a mic. Phantom power wont pass through a preamp to the mic and could possibly damage the Phantom supply. An external preamp should have phantom power so you would shut off the Phnatom supply from your interface, then just use the phantom from the external preamp.
There are also these vocal effects units singers use. They plug their mic into the effects unit then plug the effects unit into the interface. You wouldnt want the interface supplying phantom power in this case. Phantom power cant pass through a circuit in a unit like that. Phantom must ALWAYS be supplied directly to a mic.
The only other possibility for an issue is if you make your own mic low impedance cables and screw up soldering the wrong wires to the XLR plugs. Otherwise use good factory made cables for the mic and you'll never have a problem. Phantom is likely fused to shut down is it is shorted in better units. Its not something you want to abuse of course. The phantom is more likely to shut down then blow a mic out but you never know with the quality of some gear. Main thing is is the mic doesnt come on quickly once phantoms supplied remove the power immediately and find out whats wrong.
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