Microphone cable problem - AVS Forum
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post #1 of 2 Old 11-08-2002, 09:01 PM - Thread Starter
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Folks I have a problem that I'm hoping someone can help me with.

I'm trying to setup voice automation/activation in a particular part of my house. The room has a UTP CAT5 cable that runs down to my computer. I put a mic-preamp down by the computer and connected one end of the UTP CAT5 to the mic-preamp. I put the mic in the room and connected it to end of the UTP cable in that room.

What I found was that when I listened in at the mic-preamp by pluggin in a headset, I was hearing a radio broadcast. it appears my cable is picking up interference.

How do I correct this? I've got the same type of cable working flawlessly for LAN use, so I'm not quite sure why this cable has interference.

Please let me know if you have any ideas what might be causing this or how I can resolve it.

Thanks in advance.

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post #2 of 2 Old 11-13-2002, 10:16 PM
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Hi, I had a similar problem and here's what I think I know:

I think you are lucky you have radio interference instead of static.

You need to find out if it is a balanced or unbalanced mic. Balanced is basically 2 wires plus a shield and unbalanced is one wire and a shield. Its most likely unbalanced. If it is unbalanced you can't run it more than 10 or 15 feet without interference.

Also, ground the shield only on the amp side and leave the other end free. I don't know about using CAT5 wire for mics, but I read in this forum that people use it for that a lot on security camera mics--if it is shielded it should work.

You may want to try reversing the polarity of the wires or trying different pairs. If that fails, get some shielded 18ga 2 strand wire at home depot and solder the connections--be careful that the hairs on the shield are not where they shouldn't be. Use an ohm meter to check for shorts between the three wires.
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