mic randomly goes quiet

[Patrick Horgan]

This may seem obvious to more experienced folk, but I'm tearing my hair out. I run sound for a Buddhist sangha, and we have been having problems with the mic cutting out, and just by unplugging and replugging the mic, the sound comes back.
We rent space in a Unitarian church, and they have a panel on the wall with a couple of xlr connections to go to their amp.

Their amp does not provide phantom power and the usual presenter's favorite Countryman earhook requires it, so we have a small Rolls three mic mixer just to provide the phantom power (it provides 12 VDC) and then to plug into the house system. It worked fine for more than a year, but then started randomly shutting off.

While trying to diagnose this problem we:
o replaced the cable on the countryman
o substituted a Rode lav for the countryman
o substituted another Rolls mic mixer
o substituted a ProFX 8 v2 which supplies 45 VDC phantom power

Eventually we had substituted everything except for the house system, but I can't think of a way that the house amp could fail in a way that unplugging and replugging the mic would instantly and reliably fix it.

 

[Art Welter]

Patrick,

Sounds like you have ruled out your end of the system as being at fault.
Unplugging and plugging in a phantom powered mic often creates a high level transient with enough amplitude to "break through" a dirty/tarnished connection.
It is possible that the connections between the wall panel and the xlr connections to their amp/mixer have become oxidized enough to not pass lower level signal, unplugging and plugging those back in several times might reduce the tarnish enough to work consistently- cleaning those connections with a cleaner like DeOxit may fix the problem.
If that is not the problem, their mixer itself may have internal connection problems requiring either cleaning or re-soldering connections.

Art

 

[Patrick Horgan]

Patrick,

Sounds like you have ruled out your end of the system as being at fault.
Unplugging and plugging in a phantom powered mic often creates a high level transient with enough amplitude to "break through" a dirty/tarnished connection.
It is possible that the connections between the wall panel and the xlr connections to their amp/mixer have become oxidized enough to not pass lower level signal, unplugging and plugging those back in several times might reduce the tarnish enough to work consistently- cleaning those connections with a cleaner like DeOxit may fix the problem.
If that is not the problem, their mixer itself may have internal connection problems requiring either cleaning or re-soldering connections.

Art

I hadn't thought of a transient punching through a resistive connection. Hmmmmmm. Nonetheless the house isn't interested in doing anything so we're using a powered speaker/amp and everything seems fine -- except we don't have the house's assistive listening devices. Looking into getting our own. Thanks for your help. Wish I had more control/access