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Star Quad Cable vs Two Conductor Shielded

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David Shippee:

I am the volunteer in charge of sound and video at my church. The church is located about half a mile from an AM radio station broadcast antenna. For years we have had problems with intrusion of the station signal into our sound reinforcement and now into our live stream. Over the years things have improved greatly with the installation of better quality cables everywhere in the system. The radio station has offered some help as well. Regrettably most of the advice has been ineffective.

Now to the question. Do you think that star quad cable would have better resistance to radio frequency interference than regular two conductor shielded cable? It appears to be used when magnetic interference is an issue in studios. How about radio interference? I need to install some new cable along a support beam and replace some other cables under the church in the crawl space. The shortest run will be about 50 feet and the longest about 100 feet. Should I spend a bunch of extra money on this cable? Has anyone had experience with this type of issue?

Thank you for your time.

Kevin Maxwell:
One time in a church youth room (that years ago was their main sanctuary) they told me they occasionally had a radio station broadcast coming over their sound system. This had been going on for years, even when it was their main sanctuary. I tracked it down to a badly wired Electrical outlet, it was miss-wired and there was a small hole in one of the wires and the screws were loose. I fixed it and they havenít had the radio station interference since. The outlet was used for the keyboard and I donít think they even had a keyboard amp. It was just coming from the keyboard.

Can it be ran inside 1/2" EMT?  Electrical Metallic Tubing

Having done DJ club installs in buildings with FM radio stations back when we ran all analog setups with turntables.  You would probably be best served finding a consultant to assist you.  Many times noise comes into a system through power supplies in the equipment.

Bonding, grounding, shielding and testing with swapping out some equipment components are all things to try.

I don't know the properties of the quad cable you mentioned so can't help you there.

As Kevin mentioned above, disassembling the setup and building it up one block at a time to try and isolate the source.  Try shorted inputs.

Try and find some help with it.  What area are you located?

John Roberts {JR}:
Star quad is better but may not solve your problem. I wouldn't expect a simple answer.

 RFI can get in through many vectors. It can even come backwards into an audio power amp through the speaker wires.

Try to trouble shoot what gear is suffering and under what conditions.


Keith Broughton:
Before throwing new cable (and $$)at the system, try to narrow down where the interference is getting into the audio chain.
That said, if it is a cable issue, Quadstar has very good rejection capabilities and/or use EMT conduit as suggested.


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