Getting FM from my speakers without a receiver???


Spinning some vinyl today and between cleanings I had my ear close to the speaker. I was shocked to hear a local FM radio station coming out of the speakers ???? No I do not have a receiver. If this pure RF bleeding in? WTF?
I hope this can be eliminated. Any ideas?
128x128blueskiespbd
OK so here is the update. I switched from my Linn preamp to a spare Parasound I have and the FM went away! The cables from the Basis TT to the pre amp appear to be pretty cheap and unshielded. So now I wonder if I rewire the TT cable wll th RF go away???
Sounds like a good bet to me. Unshielded phono cables strike me as an invitation to this kind of problem, considering the low signal levels and high gain factors that are present.

I would suggest, though, that you verify that you don't hear the radio signals with the Linn preamp when nothing is connected to its phono inputs, and/or with shorting plugs connected to its phono inputs if you have them available.

The different results between the two preamps are likely due to the happenstance of the different characteristics of their input circuits -- one demodulates the rf signal and one does not.

Also, similar to the discussion in the other thread that I linked to, I suspect that you are really hearing am, not fm. I can't envision a means by which an audio system, apart from a tuner, can demodulate an fm signal.

Regards,
-- Al
I had to get rid of all my amalgam fillings for this very reason.

Congrats on tracking it down. The better cable suggestion should show a result.

The AM band is fairly long wavelengths, so I'm sure that changing 'antenna' orientation would help, but that should also be tried.
You could also try secondary shielding OVER the offending cables. Ground it at only 1 end.
Bad amalgam fillings you say? Would be cheaper to replace analog gear than pay $$ to my hi end dentist. I am researching wiring upgrade presently and that route sounds like it would improve the sound quality anyway.
The station is Fm and they do not broadcast a duplicate signal on Am to my knowledge.
What could I place over cables to shield them?
Do you have any gear with a switching powersupply?
Such power supplies operate NEAR Intermediate Frequencies of both FM (some) and more common AM radios. I have no basis for thinking this could actually happen.
As for shielding, a better cable would work better than either copper foil or mesh around wires. It would be a mess to boot.

Have you tried a power conditioner? This goes back to my first line in this post... It may be coming in over the power lines, though the phono pre seems 'the magic bullet' .

post if you find the final root cause / solution