# radio signal thru sub



## mike02149 (Dec 2, 2018)

Hi,
I sometimes get radio broadcasts thru my subs (Klispch). It happens even when the subs are powered up but the sub cable is not connected to my receiver. The sub cable is about 30' long...I assume it's acting like an antenna. When I switch the phase a couple of times, it seems to go away. However, it returns when the sub is powered back on. I have the subs connected with a Y connection.
Any thoughts on how to eliminate completely? Thanks.


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## theJman (Mar 3, 2012)

Have you considered an exorcism? 

Even if the cable were acting like an antenna you would think there needs to be something inside the sub that could decode the signal in order to hear a radio broadcast.


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## dazcress (Apr 15, 2018)

Just wondering why you've got the lead unplug??


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## Linear Bass (Dec 24, 2012)

How long does this "radio broadcast" last? Is it music, AM radio news or two people talking back and forth? Your 30 foot cable (RCA?) is unplugged to eliminate this problem? Need more information as to what type of radio broadcast you are hearing, lasts for a second or lasts all day or night? This only happens when A/C is applied to the sub(s) and no A/C to the rest of your system? 

Here is a poke in the dark from what has been stated thus far.
1 - With your sub powered up, disconnect your 30 ft cable from the source end of the cable, the other end connected.
2 - With your sub powered up, disconnect your 30 ft cable from the sub end of the cable, the other end connected.

Need to divide and conquer where this RF is getting in. With a low pass filter for AF in front of your sub amp, the RF you hear and when you hear it will greatly help.


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## mike02149 (Dec 2, 2018)

Hi, the signal is faint but clear. Seems to always be talk radio (am?). It happens when the sub is powered up. Having the cable connected or disconnected does not affect it.
The only thing that affects it is the phase switch. Sometimes it takes a couple of clicks back and forth to get rid of it, then it returns after a couple of hours.
Thanks for any help you can provide!


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## Newstech (Dec 13, 2008)

You might try putting ferrite cores on the AC lines and the audio cables to trap RF interference.


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## mike02149 (Dec 2, 2018)

good idea. I'll give it a try. thanks.


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## Newstech (Dec 13, 2008)

Ooops, forgot, also make sure the AC outlets for the subs are grounded. (I know in my hundred-year-old house good grounding is not a sure thing.)


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## Linear Bass (Dec 24, 2012)

Does this broadcast (RFI) come out of both subs or just one? Try rotating the sub(s) 90 degrees to see if it goes away. So far, you have eliminated your thirty foot cable(s) and the rest of your system. I had RFI come through my system years ago, it happened very rarely and not long enough to trouble shoot. It almost seemed like 1 to 2 seconds, like somebody driving by with a jacked up CB radio, either high powered or over driven microphone. In this day and age with "wireless" a marketing tool, thus creating consumer demand, RFI is and has been getting worse, overcrowded band space, sloppy designs and careless users.

Toroid and snap on ferrite chokes are useful at keeping RFI from getting into undesired and annoying places.

Do some searching concerning Audio RFI. Palomar-engineers would be a good place to start.


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## mike02149 (Dec 2, 2018)

The fer-rite cores worked! 6 were placed on the wires inside the sub (putting them on the power cord did nothing). Thanks to everyone for their suggestions.:grin2:


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## theJman (Mar 3, 2012)

Glad to hear you found a solution.


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## Newstech (Dec 13, 2008)

mike02149 said:


> The fer-rite cores worked! 6 were placed on the wires inside the sub (putting them on the power cord did nothing). Thanks to everyone for their suggestions.:grin2:


Fantastic!


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