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Old 02-10-2018, 04:11 AM
Lease13's Avatar
Lease13 Lease13 is offline
Join Date: Feb 2018
Location: Australia
Posts: 4
Default Phantom power peaks then drops out Mbox pro

After having done extensive searches I can't find any specific solutions that work...

I have had this issue occur more than once,
I connect my Mbox pro to my computer, get everything going, inputs in, etc. and then turn my phantom power on - my mic (condenser mic, Rode NT1A) volume level peaks twice and then slowly fades out to nothing...

It then won't pick up any sound to record!
I've tried everything.

The same issue has occurred using the Mbox pro with Protools 9 on a Windows computer back in 2011, and also using most recently using a Mbox pro with Garage Band on a MacBook Pro.

I actually had the mic working yesterday ?!, perfectly fine but then it has stopped working again today... very temperamental and frustrating.

Any help would be much appreciated.
I am guessing issues such as these with it being temperamental may indicate issues with the microphone itself? or the cable? or the Mbox?
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Old 02-10-2018, 10:08 AM
albee1952 albee1952 is offline
Join Date: May 2004
Location: nashville
Posts: 34,601
Default Re: Phantom power peaks then drops out Mbox pro

The 2 meter spikes are probably not the mic. That's just the voltage coming on and settling in(it would probably act the same with no mic connected). Absolutely try a new mic cable(you should always have a spare, anyway), and try another mic as well(even if you have to borrow one, or take the Rode to a local music store and test on any mixer). Things to consider:
1-The NT1A is a "budget" mic, so don't feel bad if it needs to be replaced.
2-Try a dynamic mic(everyone should have an SM57 on hand anyway) as they will work even if phantom power is dead.
3-You must use an XLR-XLR cable for phantom to work(phantom voltage does not connect to the quarter inch inputs).
4-phantom requires all 3 conductors of the XLR cable, while a dynamic mic may work fine with only pins 2&3 working
5-phantom is easy to test if you have a simple volt meter. set the meter to DC and a scale that covers at least 50 volts and then measure from pin 1 to pin 2, and again from pin 1 to pin 3. You should see the same voltage at both 2&3, and it might not be 48(could be anywhere from 30 to 50).
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