Floor mics

[chriskreidler]

I have a floor mic plugged into an input on the stage at our theater. There is no signal, and we tried three other inputs, and none worked. I tried plugging the floor mic straight into the sound board with the same cable, and it started working. The only thing I can think of is that all four inputs on the stage are broken, which isn't true. Any suggestions?

 

[Traitor800]

What else is in the line between the mixer and the stage? Some pieces of equipment can block the phantom power from getting to the input on stage.
-Chris

 

[theatretechguy]

If you're patching with 1/4" audio cable instead of 1/4" TRS (Tip Ring Sleave) cables, you may have issues, too. Phantom power typically will only work with the 3-pin XLR jacks on your system.

 

[TimmyP1955]

If any mic line has its shield either open or shorted to one of the other pins, a dynamic mic will work, but a mic that requires phantom power will not work.

 

[museav]

I have difficultly believing that four mic inputs would essentially simultaneously fail, it could happen but it definitely makes one wonder if there is something else involved. Did you plug the mic into the same inputs on the mixer that are normally wired to the floor jacks that were not working? Do you have any mic input patching or splitting or anything else between the floor jacks and the mixer inputs? Can you tell us what mic you used for the testing and the model of the mixer?

If you plugged the mic into an input other than the floor inputs that were not working then it could be as simple as using a condenser mic and not having phantom power on for the floor input channels or some improper setting on the floor input channels, maybe the preamp gain is down or they are not routed properly.

 

[Eboy87]

To echo what the others said, what's the signal path between the microphone on-stage to you're console? What is the console (make/model)? How are you patching into the console? (Stupid question) Is phantom +48v turned on for that channel?

To me it either sounds like the mic's not getting phantom or your patch is messed up. Did you try a regular dynamic mic in each of the stage inputs to check that they work? If a dynamic mic works, then the floor mic's aren't getting phantom.

 

[FMEng]

Some consoles have just one phantom power switch, some have one on each channel, and there are some that have one switch for a group of channels.

 

[lieperjp]

I would agree with Eboy... try plugging in a regular dynamic mic to see if they work. If it does, it sounds like a phantom power problem to me!

 

[qu1cks1lver56]

echoing everyone else

try a dynamic mic in the floor jacks, and make sure theres nothing inline with the floor jacks that would block phantom power

 

[TimmyP1955]

It could be that an install that a friend fixed is not the only one in which the installers ran mic lines through an unbalanced patch bay. Best check it out.