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Advice on RFI with a new integrated amp

I need some assistance on my Exposure 2010S. The only input I am using is the cd player, but with volume turned all the way down, I am picking up radio signals. If I turn the dial to the moving coil phono setting, even though nothing is attached to it, I can hear radio pretty loudly.

The corner of the house where our stereo is in under the outside wires, and it sits right next to the terminal for our Verizon Fios -- not the most ideal location, but it
is the only option.

Using the CD pots on the amplifier, you can only hear the radio pretty faintly, when the volume pot is turned all the way down. If I am playing cds, you can't hear anything, but since when I switch to the phono/aux1 setting, as I mentioned, I am picking up radio signals, and
the volume is louder. From what I read (and hear), it appears that the phono pot (perhaps in cahoots with the moving coil phono stage) is acting as a antenna, and picking up signals, which are cross-talking
across the other inputs on the amp.

How would you recommend addressing this? I am currently considering
shorting terminators on the phono, and other output pots and found some terminators online (audiophilia article).

At first I thought it might be my changing the speaker cables, from very thick cables to the slimmer DMNs, but that would not explain why the RFI is louder at the phono input than any of the others.

Whatcha think? Does this make sense?

The other option would be RCA caps.

Thanks,

Marty
martyw

Showing 8 responses by jea48

jea48
4,635 posts
 
Not all ferrites are the same.

Marty if you try ferrites on your speaker cables and or power cord make sure you install them as close as possible at the entry point of the amp.
jea48
4,635 posts
 

I am currently considering
shorting terminators on the phono, and other output pots and found some terminators online (audiophilia article).
Do not install shorting plugs on the outputs. Ok on the inputs....

At first I thought it might be my changing the speaker cables, from very thick cables to the slimmer DMNs, but that would not explain why the RFI is louder at the phono input than any of the others.
Does the radio station get louder if you increase the volume?

How long are the speaker cables?
If you still have the old speaker cables reconnect them and then listen for the radio station.
jea48
4,635 posts
 
So the shorting caps didn't address the RFI, even when in the phono stage. Would the next step be swapping out the moving coil stage and putting back in the other piece (I am not sure what its is called -- I think internal jumper? If so, who can do that?
11-21-09: Martyw

The only input I am using is the cd player, but with volume turned all the way down, I am picking up radio signals. If I turn the dial to the moving coil phono setting, even though nothing is attached to it, I can hear radio pretty loudly.
11-17-09
Not sure if the question was asked and answered. What happens if the CDP ics are disconnected from the Exposure 2010S? With the selector switch set to the CD source is the radio station louder?
jea48
4,635 posts
 
Marty,

You might try some clamp-on ferrite beads on the power cord of the amp and on the speaker cables.
You never answered how long the speaker cables are....

RFI Tips And Tricks
Quote from Link:
AUDIO AMPLIFIERS
It's quite likely that the audio amplifier is performing RF detection. You need to place ferrites on the speaker cables as close to the audio output (right at the PC board if possible) with as many windings as possible. If it is audio detection, it won't matter at all how many ferrites you install on the power cord or cable TV or antenna cable although this will cut down on the amount of
RF getting into the TV via those conductors. Direct pick-up onto speaker wires causes most problems. Don't go into the television if it is not your own.

Jim
jea48
4,635 posts
 
Hi Al,

You are probably right but if Marty has some ferrite beads it won't cost him anything to try them on the speaker cables and or the power cord. Maybe the radio tower transmitting antenna is close to where Marty lives..... Or maybe it is a hi-power radio station.

The amp received a good review from Stereophile and I can't imagine the proper shielding was not incorporated into the design and build of the unit.

Is it possible the amp could sound good and still have a cold solder joint somewhere along a signal ground path?
Jim
jea48
4,635 posts
 
Marty,
Is this your speaker cable?
http://www.dnm.co.uk/cables.html
http://www.stereotimes.com/cable022205.shtml
jea48
4,635 posts
 
Marty,

Might be a waste of your time but I would go to HD or Best Buy and buy some cheap twisted pair speaker cable and see if it solves your problem. Flat ribbon speaker cable is prone to RFI,... works as a good antenna.

Another thing to check out is the radio station. Do you know for sure which one it is. If so give them a call and ask to speak to their engineer. Ask him if they are broadcasting also in AM. Also explain your problem to him. He may be able to help. At the very least he will give you the broadcast transmitting frequency.
jea48
4,635 posts
 
Marty,

If the DNM speaker cable is acting as an antenna , in your situation, parallel wire (Zip cord) will more than likely do the same thing. Read page 11

You will need to use twisted pair cable. You might check Radio Shack for some cheap cable and banana plugs for testing. If it solves your problem then you can buy something better.
Jim
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