HELP with microphone wiring in wall

Posted: Thu Apr 30, 2009 6:47 am

I have built a studio in my basement and have a control room and performance room with xlr wiring between the two. If I connect a standard microphone to the xlr jack in the performance room, then from the xlr jack in the control room to the mixing board, everything works fine. However, using a condenser mic connected in the same manner (with phamtom power on mixer), I cannot get a signal. If I connect the condenser mic directly to the mixer, it works fine.

Is there something with the xlr pin-out in the wall I should have done differently or possibly another problem that could be causing the issue. Any help is greatly appreciated.

Posted: Thu Apr 30, 2009 9:28 am

I would examine the pinout on your two panels. You may have something backwards. The phantom power is DC, so polarity [+] [-] will usually matter.

I've seen a lot of them wired wrong, where the installer went left to right on both the male and female.

For example if you were looking at the solder tabs:

Shield on the left / Black in center / Red on the right

That would be OK on the female XLR, but if you used that exact same left-right method on the male XLR - only the black would be correct. You would have the shield and positive reversed - and a lot of dynamic mics will still function that way.

As you can see from this FRONTVIEW graphic they have to be wired mirror image:

You have to confirm by looking at the numbers

Pin 1 is ALWAYS the shield wire. Make sure the color code you use for Pin 2 and Pin 3 is the consistent and you'll be fine.

Posted: Thu Apr 30, 2009 9:46 am

Because phantom power (PP) is a common-mode signal, it does not care about the polarity of the signal pins. The ground (XLR pin1) is always PP negative, and the signal pins (2 and 3) are always PP positive.

Check your connections, as Hawk suggests, but one likely thing that would allow a dynamic mic to work and prevent a condenser mic working is to have a short circuit between either pins 1 and 2 or between pins 1 and 3 on your wall XLR jacks, or in the cable run between the performance room and the control room.

Posted: Thu Apr 30, 2009 1:51 pm

Hey dvdhawk, that was the problem. I had the wires matched on both sides of the female xlr plates, but apparently I needed to swap pins 2 & 3. Thanks a million.

Posted: Fri May 01, 2009 6:20 pm

The OP's question has been answered so I hope no one minds if I hijack this thread since there are so many cable experts here already. Is there any danger (to equipment or people) in plugging one XLR cable into another one to extend it? Loss of signal quality? Didn't want to just try it in case I destroyed something. From the pin digram above, unless I'm failing at reversing one in my mind, 1 would still be connected to 1, 2 to 2 and 3 to 3, wouldn't it?

Posted: Fri May 01, 2009 6:34 pm

apstrong,

Danger - There's no danger at all, assuming both are wired correctly you'll be perfectly fine. Even if one is wrong not much danger.
Loss - Just a tiny bit of loss caused by the connectors. A continuous run of wire would have a very slight advantage.
Pinout - Yes, you are right. A male XLR connector plugged into a female XLR ends up Pin 1<->1 / 2<->2 / 3<->3 from one end of the signal chain to the other.

Posted: Sat May 02, 2009 2:03 am

Thanks. I'm paranoid about plugging one thing into another thing just because it looks like it will fit.

You can insert your own jokes here. Smile

Posted: Sat May 02, 2009 5:30 am

apstrong wrote:

Thanks. I'm paranoid about plugging one thing into another thing just because it looks like it will fit.

You can insert your own jokes here. Smile

heheheheh... nawwww....

I can't do it... You said it too nicely. Smile

Just be sure that you are aware of the fact that where you are plugging stuff up, that faders, gain pots and amplifiers should be turned down... it'll save speakers in the short run, and lots of other circuits in the long run.

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