I’m writing this during a church service, where the phantom power on 3 channels was turning itself on and off, causing a bit of havoc on my pulpit mic (condenser) and 2 wireless lav’s, causing the latter to jump way up and down in gain. At some point it stabilized and I was able to finish the service, but I have no clue how this was happening. The board (Qu-16 running 1.97) getting all signal from an AB168, was not networked, so no possibility of someone bringing in a tablet and messing with me from an app. The only thing I can think of that isn’t firmware gremlins would be that perhaps the touchscreen thought there was a finger poking the 48v periodically. This was happening on channels 1, 3 and 4. Channel 2 was stable the whole time.
You can see the troubles on this video starting at 24:24 and continuing until about 34:40
Anyone have any ideas why this would have been happening? This board is less the three years old, I believe. Only used on Sundays for the most part.
I would doubt that it could be related to switching the phantom power off and on, because that would certainly have been accompanied by loud crackling noises.
Furthermore: Are you actually using wireless microphone receivers that are powered by phantom power???
I would assume there’s some other cause.
Is there, for example, perhaps a mute group for channels 1, 3, and 4?
It’s probably not phantom power, as mentioned you likely wouldn’t use it on wireless systems. I myself don’t with any mic unless it’s a wired condenser.
It also seems too clean of an audio cutoff for phantom power, more of a mute instead.
OK, so apparently I didn’t explain this properly. THE PHANTOM POWER ON THOSE CHANNELS WAS TURNING ITSELF OFF AND ON WITHOUT MY DOING IT. I was able eventually see it engage and disengage, hence why I thought that it might be a touchscreen issue.
Sorry for the yelling. Also, no other function seemed to be triggering (such as the mute buttons).
Please excuse my attempt to help you yesterday - only after no one else responded.
English isn’t my native language, and besides, a sound engineer’s extensive experience isn’t immediately apparent from a first post.
But if it’s as you describe, and phantom power is muting or changing the levels of even wireless systems channels on its own and at random, it’s most likely not a firmware issue, but rather something beyond our control.
You’ll probably have to submit a service ticket to A&H.
As mentioned wireless mic receivers do not need or even should have phantom power applied to them, I have seen a couple odd issues with equipment getting hit phantom power that was not needed.
So if your watching the preamp menu you can see the phantom power turning on and off?
If the screen is on another menu does it happen then? If so I would not think it’s a touch screen issue.
Do you have the mixer connected to a router or network for remote control with an iPad? Is the USB B connector connected to anything?
It does sound almost too clean for turning phantom power on and off, many mics will make a thump or some noise powering on and slowly fade out when you shut off the phantom power with some noise.
I assume the mic at the lectern is hardwired direct to the mixer or is it on a wireless transmitter?
The wireless do not have phantom applied, but in that situation it was being turned on and off somehow. They are usually pretty clean.
I was able to see the phantom power turning off and on, yes.
I cannot definitively say if it was happening with the screen on another menu, but it is possible, even probable.
The mixer was not connected to an iPad or a network until the trouble started happening; I hooked that stuff up so I could walk to the pulpit mic and check for levels once I changed out that microphone. The only ethernet connection was the Slink to the AB168.
The mic at the lectern (and the pulpit) is directly connected to the stage box.
Another interesting thing to note: apparently an outside door with a handicapped motor wasn’t closing all morning either. While I always disconnect the mixer from power after service, the stage box is always plugged in, although it is always shut off via a light switch style breaker. Perhaps it’s possible that the building was hit with a power surge or a lightening strike over the course of the week.
