Radio station in long mic lines

[Dallas]

Good afternoon,

I am wondering if anyone has had issues with radio stations in their Qu mixers? I have worked with 2 permanent installs that this became and issue. Both have moderately long runs. In the first case I was able to alleviate the issue by changing the mic cable length. The other, one of our techs was on site today and I have not talked to him yet. Both systems previously had Mix Wizard or GL2400 mixers without the issue, all other system structure remained the same, just a mixer replacement.

[mervaka]

What are the symptoms?

[Stonepiano]

Whatever the symptoms, if you need to run long analog lines, make sure you have cabling that’s specifically made for those.Check out the Cordial catalogue. Or get a stagerack and run Cat5.

[GCumbee]

I have never had many problems with RFI but have seen it from time to time. My suggestions.

Try one piece of new cable that is a quad type cable with twisted pairs. Canare or Mogami makes this.

Try changing the microphone. Don’t know what you are using but have seen cases with knock off brands that are unbalanced with no transformer. Open invitation to RF.

Other obvious thing is to check XLR connectors for good shield connection. Make sure the shield is NOT soldered to the lug making the shell a ground. In the right conditions that can get into the electrical ground of the building and wreak havoc.

I have seen one situation where a console (not AH) with differential input(no xformer) picked up nearby radio station.

In my Nashville studio we had an AM station about 1/2 mile away. Generally not a problem except at times some pieces of outboard gear mainly mic pres would pickup a low signal. But only certain pieces. Most didn’t.

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