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Remove Radio Station Background Noise

What is the best way to remove radio station sound from the TT feed to the pre amp? 

When I turn the volume up to about 50% I can hear radio station noise if my ear is next to the speaker.

I started using clamp-on ferrite chokes that clip around the cables from the TT to the phono preamp to eliminate the noise.  I wanted to know if there is a better solution or if the ferrite chokes compromise the sound.

 

The TT is a VPI Classic 3. The phono preamp is a Sutherland PhonoBlock and the pre amp (DMC-30SV) and amps (DMA-400) are Spectral Audio.  All cables are MIT Oracle MA-X. 

bigby
hifi78
6 posts
 

The antenna is likely your tonearm cable, where it loops over top of the arm. Reach out to VPI for their input on solutions. 

stringreen's avatar
stringreen
6,372 posts
 

I have all balanced cables...dead quiet

hagtech
173 posts
 

Sometimes there is nothing more you can do besides ferrite beads. Not that I recommend them, but they can work if done right.

The problem isn't your cable (XLR or RCA), the problem is RF signals (radio) are getting into your phonostage and it is demodulating them.  You must low-pass filter the signal BEFORE it hits silicon (transistor, fet, opamp)!  Radio demodulation is all happening at the input of the first stage.  The output of that stage does not have enough bandwidth to amplify RF.

PN junctions are the culprit, even parasitic ones.  Tube phonostages do not have as much of a problem.

The cure that I use in many of my designs is an RC low pass (set above 100kHz) right before the first semiconductor junction. This is sort of what your ferrite is attempting to accomplish. 

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