mat_hans

Electromagnetic interferences

5 posts in this topic

We purchased several MB-3 mics (more than 50) for our video conferencing needs and are finding out that they pick-up GSM cellphone incoming calls very nicely resulting in a very annoying buzz on the other end of the conference call :blink:

The underlying EMI problem seems quite well-known (refer to AES48-2005 standard and do a google on the term "pin 1 problem").

We have not yet considered returning the mics and are currently looking for a fix. According to http://audiosystemsgroup.com/Pin_1_Revisited_Part_2.pdf Neutrik has EMC connectors that could resolve this problem. Unfortunately, I cannot seem to find these connectors on http://www.neutrik.com site.

Any suggestion?

--Mat Hans

Hewlett-Packard

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Here is a link with some suggestions:

http://www.crownaudio.com/kb/entry/163/

Also, make sure that the mic cable shield is connected directly to your input device's chassis (probably your mixer's chassis). At the mixer end of the mic cable, solder a thick wire to XLR pin 1 and route it outside the XLR connector, then attach it under a chassis screw. This might reduce RFI pickup by the mixer, but will not reduce RFI pickup inside the microphone.

You might also solder a jumper wire between pin 1 and the ground lug in the XLR connectors on both ends of the mic cable. Caution: This grounds the XLR shell, and might create a ground loop if the connector shell touches metal.

brubart

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Hello an thank u,

i've tried one of our hand mics on the audio line to the PZM-6D mic. If i use this mic there is no problem with any RF noise. I conclude that the RF noice comes over the PZM-&D mic. I'm not confident that a EMC XLR cabel fix the problem cause with another mic there is no RF noice.

What is your opinion?

regard

Helmut

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That was a good test, Helmut. Is your handheld mic a dynamic type? If so, it has no internal electronics which can pick up and rectify RFI. The PZM is a condenser mic, so it does have internal electroncs which can pick up RFI. You might need to use dynamic mics in your application.

Good luck,

brubart

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