Help with speaker interference!

[sternre]

My tv sound is connected through my stereo, but when I mute the tv (or if the tv is off), there is faint radio music playing through my speakers. It's not the receiver because I tried changing that and the problem did not go away. It didn't happen when the system was first set up, but after a couple of years it kicked in and hasn't stopped. Any ideas why this is happening and what I can do about it? Thanks for any help!!!

 

[bandphan]

is your video source cable or sat? You might be picking up fm interference, call the cable company if so and have the come put a notch or band pass filter at the entry point.

 

[TLS Guy]

is your video source cable or sat? You might be picking up fm interference, call the cable company if so and have the come put a notch or band pass filter at the entry point.

The radio signal is quote likely being picked up by your speaker leads and being rectified and transfered to the output by the high gain stages of the receivers.

Try disconnecting the speakers and listening via headphones and see if you still hear the radio station. If you don't, then you need to place RF chokes on your speaker terminals.

 

[roshi]

I 2nd the choke idea. Specifically try a Ferrite Filter, you can buy it at Radioshack.

 

[sternre]

Thank you!

Thanks for those replies. I'll let you know if I still have an issue.

I appreciate your help!

 

[Midcow2]

Time to consider some shielded Blue Jean Cables ..

Time to consider some shielded Blue Jean Cables .. to connect your speakers. If your speaker wires are acting as an unshield antenna that is bad.

http://www.bluejeanscable.com/store/speaker/index.htm

 

[jcPanny]

Speaker cable

Time to consider some shielded Blue Jean Cables .. to connect your speakers. If your speaker wires are acting as an unshield antenna that is bad.

http://www.bluejeanscable.com/store/speaker/index.htm

FYI,
from the BlueJeans website:
"Speaker cable is a bit different from a lot of the interconnect cables we handle, in several respects. Because speakers are driven at low impedance (typically 4 or 8 ohms) and high current, speaker cables are, for all practical purposes, immune from interference from EMI or RFI, so shielding isn't required. "

They don't even offer shielded speaker cable. Keep in mind that your speakers can only reproduce (and your ears can only hear) up to 20kHz. RF noise is typically in the Megahertz to Gigahertz range.

 

[TLS Guy]

FYI,
from the BlueJeans website:
"Speaker cable is a bit different from a lot of the interconnect cables we handle, in several respects. Because speakers are driven at low impedance (typically 4 or 8 ohms) and high current, speaker cables are, for all practical purposes, immune from interference from EMI or RFI, so shielding isn't required. "

They don't even offer shielded speaker cable. Keep in mind that your speakers can only reproduce (and your ears can only hear) up to 20kHz. RF noise is typically in the Megahertz to Gigahertz range.

Here is a common misunderstanding. Shielded speaker cables have a capacitance that is too high. I run mine in steel conduit.

Now RF interference is very high frequency, well out of the audio range. So is an FM radio signal, but you still get to hear it as audio. However the speaker cables have a direct route to the high gain amp stages, through the negative feedback circuits of the amps. The base emitter junctions of the transistor or these days ICs are also diodes! So just like the crystals sets of old, they can detect and rectify a radio signal and make it audio, to be amplified down the rest of the chain.

In HT by far the commonest RF that causes trouble by pick up in speaker leads is RF that is radiated by light dimmers.

However I have had many occasions over the years where speaker leads pick up a local radio station, and you here it faintly from the speakers.

 

[Phil Taylor]

You wouldn't happen to be real close to a radio station's transmitter tower would you?