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Phono interconnects acting as antenna, adding noise to system

Have interesting problem with cable related noise. I have a coincident phono amplifier and biamped coincident speakers with dedicated 20 A circuits from a separate panel share a common star ground (independent from rest of house).  

There is not ground hum, but when phono to amplifier interconnects connected to amplifiers a course EMF like noise occurs.  The cables seem to be acting as antennas since the noise does not change if disconnected from phono amp but stops if disconnected from power amplifier.

Interestingly, the interconnects are 12feet long running in galvanized conduits under floor to the phono amplifier

The noise is louder if i run in air outside of the conduits.  When in conduits only 3 feet at either end is exposed.

does anyone have any suggestions?  read that there are braided copper sleeves could try with exposed part?  use tinned copper tape?   or is there something else going on?
128x128jricci
rbstehno
1,454 posts
 
Try shielded cables for your phono connections. That's what I use and they are dead quiet
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jricci OP
10 posts
 
Would running cables through a braided sheild in the conduit work?


jricci's avatar
jricci OP
10 posts
 
My system Frankensteins and coincident phono stage are unbalanced

fineito
34 posts
 
If you read some of my prior posts on hum you will learn I had what seems to be a similar problem on my phono source.  I wrapped my tonearm cables in aluminum foil and that took care of the problem.  I think they were picking up hum from my Audio Valve Baldur 300 monobloc transformers.  Tom.
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cleeds
5,957 posts
 
jricci
Would running cables through a braided sheild in the conduit work?
Before undertaking additional work, you should try correcting your improper electrical safety ground that is " independent from rest of house " and be sure that it is properly bonded to the neutral bus bar in your electric service panel.
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