Guys, I'm stumped. I'm getting a spanish radio station blasting through my stereo on every input and in every speaker. There's a radio tower (AM, I think) that's about 500 yards from my house. I think narrowed it down to the speakers or speaker wire, but don't know what to do next.
Gear: Denon receiver, Polk Surrounds & Center, Canton Fronts
Speaker Wire I'm using
Steps I've taken:
- Ensure the outlet I'm using is grounded
- Tested with headphones. As I'm listening on my headphones, as soon as I start to unplug each speaker, the radio signal gets quieter and disappears when I unplug the last speaker cable.
- Ferrite Rings on ever speaker cable and power cable. Didn't have any effect.
- Shielding wire for the full length of a speaker cable. Didn't have any effect.
- Called Denon. They just told me to reset the receiver and if that didn't work, then I need to send it in for servicing. Reset didn't do anything.
- When I turn on the "Eco" function on the receiver, the sound goes away (but that essentially just turns off the surround speakers).
- Plugged in the radio receiver that came with the Denon. No effect.
Are there any experts out there that can help me before I throw everything away and buy a soundbar?
This is a common problem when near a radio or TV tower. Yes, the speaker wires do act as antenae, and feed the radio signal back to the early high gain stages via the negative feedback circuit. This signal then gets rectified by the first semicondctor junction it meets and you the hear the station, as you have an amplified crystal radio!
Now I don't think those ferrite Rings will make any difference.
One thing is that you need to use twisted speaker cable, not what you are using. Belden 14 or 12 AWG is what you need. The cable you are using is the worst for this problem.
What I have done in the past when I lived close to the Crystal Palace TV tower many years ago, was to get some ferrite rods, and some 12 or 14 Gauge solid enameled wire and wrap 5 to 10 turns around the ferrite rods about 2" inches or so long and put them in series with the positive speaker leads right at the output from the amp.
Now you must scrape off the enamel from the ends you connect the speaker wire and the receiver. Use electrical tape to stop the coil unraveling and the rod moving through the coil.
In my case this did the trick. Now if this is not good enough then you might have to convert this set up to a tuned rejector circuit, by shunting your DIY inductor circuit with the right value cap.
If this is required you need to seek the assistance of the engineering staff of the radio station. Federal law requires operators of radio and TV stations to assist individuals suffering from these issues, in any reasonable way. If they refuse, then this old man can probably remember how to design a tuned RF rejector circuit once I know the radio frequency of the signal causing this problem.
The other thing that could be done, is to shunt the input junctions of the power amps with a tuned acceptor circuit. However, this would require know how and skills. I doubt you will find anyone willing to do this for you. I did have to do this in my case. It was not difficult as it was a tube amp.
This is another one of my beefs about receivers. The law requires that they have built in rejection of these unwanted signals. The lousy receiver manufacturers widely ignore this, to shave a few cents.
This is especially problematic because of LED light bulbs especially when controlled with SCR dimmers. These make a lot of RF, and you have to really wire your house to minimize it. This is a potent source of RF and causes hums and buzzes often confused with ground loops.
Lastly I have to be honest, that not all these cases can be solved. Some defy resolution, and the only remedy is then to move to a residence much further from the offending tower.